Design of Protective Covers Against Natural Hazards 
 
by 
 
Vladimir Quinones Silva 
 
 
 
 
A thesis submitted to the Graduate Faculty of 
Auburn University 
in partial fulfillment of the 
requirements for the Degree of 
Master of Science 
 
Auburn, Alabama 
May 9, 2011 
 
 
 
 
 
 
 
Copyright 2011 by Vladimir Quinones Silva 
 
 
Approved by 
 
Gwynedd A. Thomas, Chair, Associate Professor of Polymer and Fiber Engineering  
Peter Schwartz, Professor of Polymer and Fiber Engineering 
Sabit Adanur, Professor of Polymer and Fiber Engineering  
ii 
 
 
 
 
 
 
 
Abstract 
 
 
The purpose of this project is to design a protective cover against natural hazards for aircraft, 
vehicles, and ground structures. Protection against natural hazards is necessary for maintaining the 
integrity of a vehicle or aircraft. Some of the most commonly encountered natural hazards include 
exposure to sun (UV light), heat, and hailstones. The design of a protective cover against such 
natural hazards for aircraft, land vehicles, and structures was studied in this thesis. The objective of 
this research was the creation of a polymer-fabric based flexible structure designed to protect 
aircraft, ground vehicles, and housing and storage structures in a wide range of naturally challenging 
or hostile environments from impact damage, thermal damage, and ice loading damage. The 
protective cover was designed and evaluated using different methods for their physical 
characteristics. For this purpose, individual tests were performed to evaluate the best material for 
each layer; the mentioned tests were: area density, abrasion, friction, folding, UV resistance, impact 
resistance, tear resistance, bursting strength, static charge resistance, flame resistance, air 
permeability and hail impact simulation. The consolidated composite was assessed in a test chamber 
simulating real hail stones. The ice projectiles that were used had different constructions and 
diameters. Information, such as velocity, peak force and displacement was collected using a high 
speed camera, dynamic force transducer, and a laser displacement transducer. Results of this 
experiment revealed that the material is suitable against hailstone impact for hailstones up to 1.6 
inches in diameter, which are more common than 2 inch diameters.   
Resistance to impact is most critical for protection during hail storms, and therefore, we set out 
to develop an impact resistant covering against hail stones up to 2 inches in diameter. Future work 
iii 
 
should be performed using additional layers utilizing high strength ballistic grade yarns such as 
Kevlar? or ballistic nylon.   
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
iv 
 
 
 
 
 
 
 
Acknowledgments 
   
  
The author would like to express his utmost thanks to his advisor and mentor, Dr. Thomas, for 
her guidance, encouragement, support, and valuable advice for every step in the completion of this 
research work. The author is also grateful to his committee members, Dr. Peter Schwartz, and Dr. 
Sabit Adanur for serving on my graduate committee and for offering their suggestions and help. In 
addition, he is thankful for Dr. Ramsis Farag?s continuous support and help during the project?s 
laboratory studies. Special thanks to Mr. Jeremy Duffey for his excellent help and technical support. 
The author would like to give thanks to the Department of Polymer and Fiber Engineering for 
providing support and an exciting research environment, especially to the technicians for their 
discussion and brilliant recommendations. Thanks also go to his research colleagues, Katie, Idris, 
and David. Finally, the author would like to express his deepest thanks to his parents who supported 
him from a distance.  
 
 
 
 
 
 
 
 
 
v 
 
 
 
 
 
 
 
Table of Contents 
 
 
Abstract ................................................................................................................................................. ii 
Acknowledgments ............................................................................................................................... iv 
List of Tables ..................................................................................................................................... viii 
List of Figures ....................................................................................................................................... x 
1. Introduction .................................................................................................................................. 1 
2. Literature Review .......................................................................................................................... 3 
2.1 Summary ............................................................................................................................................. 3 
2.2 Objective ............................................................................................................................................ 4 
2.3 Effects of natural hazards in expected use .................................................................................... 4 
2.3.1 Sun and heat .............................................................................................................................. 5 
2.3.2 Bird and animal nests ............................................................................................................... 6 
2.3.3 Blowing sand ............................................................................................................................. 6 
2.3.4 Freezing rain, frost, ice and snow ........................................................................................... 6 
2.3.5 Thunderstorms and rain .......................................................................................................... 6 
2.3.6 Thunderstorms and hail ........................................................................................................... 7 
2.4 Deterioration of polymers................................................................................................................ 8 
2.4.1 Sun (UV and IR radiation) ....................................................................................................... 8 
2.4.2 Blowing sand ........................................................................................................................... 11 
2.4.3 Thunderstorms and rain ........................................................................................................ 12 
2.4.4 Freezing rain, frost, ice and snow ......................................................................................... 13 
vi 
 
2.4.5 Thunderstorms and hail ......................................................................................................... 14 
3. Experimental Design .................................................................................................................. 31 
3.1 Materials ............................................................................................................................................ 31 
3.2 Methodology to test the materials ................................................................................................ 33 
3.2.1 Areal density ............................................................................................................................ 36 
3.2.2 Abrasion test ............................................................................................................................ 36 
3.2.3 Friction test .............................................................................................................................. 37 
3.2.4 Folding test .............................................................................................................................. 38 
3.2.5 UV resistance test ................................................................................................................... 38 
3.2.6 Impact resistance (impact test) ............................................................................................. 39 
3.2.7 Tear resistance ......................................................................................................................... 40 
3.2.8 Bursting strength test ............................................................................................................. 40 
3.2.9 Static charge resistance ........................................................................................................... 41 
3.2.10 Flame resistance ...................................................................................................................... 42 
3.2.11 Air permeability ....................................................................................................................... 43 
3.2.12 Hail impact simulation ........................................................................................................... 43 
4. Experimental Results .................................................................................................................. 56 
4.1 Areal density ..................................................................................................................................... 56 
4.2 Abrasion test .................................................................................................................................... 57 
4.3 Friction test ...................................................................................................................................... 59 
4.4 Folding test ....................................................................................................................................... 59 
4.5 UV resistance test ............................................................................................................................ 59 
4.6 Impact resistance (impact test) ...................................................................................................... 61 
4.7 Tear resistance ................................................................................................................................. 62 
vii 
 
4.8 Bursting strength resistance ........................................................................................................... 63 
4.9 Static charge resistance ................................................................................................................... 63 
4.10 Flame resistance............................................................................................................................... 64 
4.11 Air permeability ............................................................................................................................... 65 
4.12 Hail impact simulations .................................................................................................................. 67 
5. Conclusions ................................................................................................................................. 79 
6. Recommendations for Future Work ......................................................................................... 81 
References ........................................................................................................................................... 82 
Appendices .......................................................................................................................................... 86 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
viii 
 
 
 
 
 
 
 
List of Tables 
 
 
Table 1 Mass calculations of hailstones ........................................................................................................ 15 
Table 2 Analytical comparison of terminal speed models ......................................................................... 19 
Table 3 Resultant velocity and kinetic energy of hailstones at 45? angle and free-fall .......................... 22 
Table 4 Terminal velocities and energies of hailstones .............................................................................. 23 
Table 5 Kinetic energies produced by ASTM, FM, and UL standards test methods ............................ 23 
Table 6 Kinetic energy of hailstones using Ross? equation ........................................................................ 24 
Table 7 Filler weight for each diameter ........................................................................................................ 51 
Table 8 Areal density results ........................................................................................................................... 56 
Table 9 Comparison of weight loss on samples after abrasion ................................................................. 57 
Table 10 Visual comparison of wear abrasion on samples ........................................................................ 58 
Table 11 Friction test results .......................................................................................................................... 59 
Table 12 Impact test results............................................................................................................................ 62 
Table 13 Tear resistance test results .............................................................................................................. 62 
Table 14 Burst resistance test results ............................................................................................................ 63 
Table 15 Electrostatic charge of materials tested ........................................................................................ 63 
Table 16 Air permeability test ........................................................................................................................ 65 
Table 17 Material selection matrix base layer .............................................................................................. 66 
Table 18 Material selection matrix inner layer ............................................................................................. 66 
Table 19 Material selection matrix outside layer ......................................................................................... 67 
ix 
 
Table 20 Test summary of ice constructions ............................................................................................... 73 
Table 21 Displacement in material ................................................................................................................ 75 
Table 22 Results after abrasion of the heat reflecting fabric ..................................................................... 88 
Table 23 Results after abrasion of the single bubble/white foil ............................................................... 89 
Table 24 Results after abrasion of the two-sided film with polyester scrim reinforcement ................. 90 
Table 25 Results after abrasion of the single bubble/double foil (circular embossing) ........................ 91 
Table 26 Results after abrasion of the single bubble/double foil (triaxial embossing) ......................... 92 
Table 27 Results after impact resistance test of the two-sided film with polyester scrim 
reinforcement ................................................................................................................................................... 93 
Table 28 Results after impact resistance test of the single bubble/double foil ...................................... 94 
Table 29 Results after impact resistance test of heat reflecting fabric ..................................................... 95 
Table 30 Results after impact resistance test of single bubble/double foil ............................................. 96 
Table 31 Results after impact resistance test of bubble wrap ................................................................... 97 
Table 32 Results after impact resistance test of polyethylene film ........................................................... 98 
Table 33 Results after tear resistance test ..................................................................................................... 99 
Table 34 Results after bursting strength test of outside layers ............................................................... 101 
Table 35 Results after bursting strength test of inner layers .................................................................. 102 
 
 
 
 
 
 
 
x 
 
 
 
 
 
 
 
List of Figures 
 
 
Figure 1 General lay-up of multilayer protective cover design ................................................................... 3 
Figure 2 Cause ? Effect tree ............................................................................................................................. 5 
Figure 3 Vehicle damage caused by hail ......................................................................................................... 7 
Figure 4 Electromagnetic spectrum ................................................................................................................ 8 
Figure 5 Principal reactions and interactions of solar radiation in polymeric materials .......................... 9 
Figure 6 Degradation of PE caused by UV radiation ................................................................................. 10 
Figure 7 Modes of failure in ice as a function of strain rate ...................................................................... 16 
Figure 8 Analytical comparison of terminal speed models ........................................................................ 20 
Figure 9 Resultant impact speed at ? ............................................................................................................ 21 
Figure 10 Quasi?static hail impact characterization spring-mass model ................................................. 25 
Figure 11 Structural model during small mass impact on plates............................................................... 26 
Figure 12 Schematic of contact between two elastic solids (rigid, spherical indenter, and flat, non-
rigid specimen) ................................................................................................................................................. 27 
Figure 13 Response during small mass impact on plates ........................................................................... 29 
Figure 14 Physical appearance of materials used in designs ...................................................................... 32 
Figure 15 Depictions of multilayer protective cover design (units in inches) ......................................... 34 
Figure 16 Abraser ............................................................................................................................................. 37 
Figure 17 Friction test fixture ........................................................................................................................ 37 
Figure 18 Folding endurance tester ............................................................................................................... 38 
xi 
 
Figure 19 QUV Weathering tester ................................................................................................................. 39 
Figure 20 Instron Dynatup ............................................................................................................................. 39 
Figure 21 Tear test ........................................................................................................................................... 40 
Figure 22 Burst test .......................................................................................................................................... 41 
Figure 23 Static test ......................................................................................................................................... 42 
Figure 24 Chamber flame resistant test ........................................................................................................ 42 
Figure 25 Frazier low differential pressure................................................................................................... 43 
Figure 26 Experimental scheme set-up ........................................................................................................ 44 
Figure 27 Experimental set-up ....................................................................................................................... 45 
Figure 28 Compressed air cannon ................................................................................................................. 46 
Figure 29 Air cannon fixture .......................................................................................................................... 46 
Figure 30 Test chamber .................................................................................................................................. 47 
Figure 31 Experimental set-up frame ........................................................................................................... 48 
Figure 32 Targets at 45? and 90? ................................................................................................................... 48 
Figure 33 Ice constructions ............................................................................................................................ 50 
Figure 34 Foam sabot for varying diameter projectiles .............................................................................. 51 
Figure 35 Pressure vs. Velocity ...................................................................................................................... 52 
Figure 36 Force transducer set-up ................................................................................................................. 53 
Figure 37 Laser displacement transducer set-up ......................................................................................... 54 
Figure 38 Composite target model detailing its composition .................................................................... 54 
Figure 39 Expected ice projectile path ......................................................................................................... 55 
Figure 40 Comparison of weight loss on samples after abrasion ............................................................. 57 
Figure 41 FTIR spectra of the outside layers ............................................................................................... 60 
Figure 42 FTIR spectra of the outside layers ............................................................................................... 61 
xii 
 
Figure 43 Test of flame resistance ................................................................................................................. 64 
Figure 44 Sample after test of flame resistance ........................................................................................... 65 
Figure 45 Volts vs. time (output signal) ........................................................................................................ 68 
Figure 46 Peak force of layered ice (57 mm diameter) at 90? impact ...................................................... 68 
Figure 47 Peak force of layered ice (40.5 mm diameter) at 90? impact ................................................... 69 
Figure 48 Peak force of layered ice (28.5 mm diameter) at 90? impact ................................................... 69 
Figure 49 Peak force vs. Kinetic energy ....................................................................................................... 70 
Figure 50 Summary of ice with cotton fillers (57 mm diameter) at 90? impact ...................................... 70 
Figure 51 Summary of layered ice (57 mm diameter) at 90? impact ........................................................ 71 
Figure 52 Peak force of ice with cotton fillers (57 mm diameter) at 45? impact .................................... 72 
Figure 53 Peak force of ice with cotton fillers (40.5 mm diameter) at 45? impact ................................. 72 
Figure 54 Peak force of ice with cotton fillers (28.5 mm diameter) at 45? impact ................................. 73 
Figure 55 Peak force vs. Kinetic energy for all ice construction projectiles ........................................... 74 
Figure 56 Comparison of force history all ice construction projectiles ................................................... 74 
Figure 57 Composite material with polyethylene film impacted by an ice projectile with cotton fillers 
(40.5 mm) .......................................................................................................................................................... 76 
Figure 58 Composite material with bubble wrap inner impacted by an ice projectile with cotton 
fillers (40.5 mm) coefficient ............................................................................................................................ 76 
Figure 59 Summary of deformation of composite specimen .................................................................... 77 
Figure 60 Sequence of the ice impact (57 mm diameter) on specimen ................................................... 78 
Figure 61 Average of weight loss vs. number cycles of the heat reflecting fabric ................................. 88 
Figure 62 Average of weight loss vs. number cycles of the single bubble/white foil ........................... 89 
Figure 63 Average of weight loss vs. number cycles of the two-sided film with polyester scrim 
reinforcement ................................................................................................................................................... 90 
xiii 
 
Figure 64 Average of weight loss vs. number cycles of the single bubble/double foil (circular 
embossing) ........................................................................................................................................................ 91 
Figure 65 Average of weight loss vs. number cycles of the single bubble/double foil (triaxial 
embossing) ........................................................................................................................................................ 92 
Figure 66 Load vs. Time of two-sided film with polyester scrim reinforcement ................................... 93 
Figure 67 Load vs. Time of single bubble/white foil ................................................................................. 94 
Figure 68 Load vs. Time of heat reflecting fabric ....................................................................................... 95 
Figure 69 Load vs. Time of single bubble/double foil .............................................................................. 96 
Figure 70 Load vs. Time of bubble wrap ..................................................................................................... 97 
Figure 71 Load vs. Time of polyethylene film ............................................................................................. 98 
Figure 72 Load vs. Extension of outside layers ........................................................................................ 100 
Figure 73 Load vs. Extension of outside layers ........................................................................................ 101 
Figure 74 Load vs. Extension of inner layers ........................................................................................... 102 
 
 
 
 
1 
 
 
 
 
 
 
 
1. INTRODUCTION 
 
 
Damage of personal property due to natural hazard is both a nuisance and an expensive problem 
that plagues vehicle and aircraft owners.  Protection against natural hazards is necessary for 
maintaining the integrity of a vehicle or aircraft. Some of the most commonly encountered natural 
hazards include exposure to the sun, heat, hail, rain, bird and animal nesting and droppings, freezing 
rain, frost, ice, snow and extreme cold, and others.  These environmental hazards are responsible for 
protective covering failures and ultimately for damage of vehicles and aircraft due to abrasion, 
surface deterioration (paints, coating), and structural damage from hailstones. These hazards are 
generally very expensive and potentially dangerous.  In order to prevent damage, and unnecessary 
repairs, the development of a suitable protective material is critical.    
The design of a protective cover against natural hazards for aircraft, land vehicles, and structures 
is studied in this thesis.  Development of a proposed design is based on the material properties and 
testing needed to prevent damage from natural hazards. The protective cover configuration 
proposed consists of an internal layer, inflatable bladder, and external protective layer.  Experiments 
are performed to evaluate the material properties. These results are used to determine an appropriate 
configuration of various proposed material layers.   
In order to evaluate the proposed material layers, an experimental enclosure for impact analysis 
of polymeric materials has been developed.  The capabilities of the experimental enclosure include 
data acquisition, high speed camera, compressed air cannon suitable for large diameter, and low 
speed impact.   
2 
 
In addition to the expected functionality of conventional protective coverings, a covering with 
significant impact resistance is needed.  Although conventional protective coverings are available 
from several commercial suppliers, none of these materials offer significant impact resistance against 
hailstones.   
  
3 
 
 
 
 
 
 
 
2. LITERATURE REVIEW 
 
 
2.1 Summary 
A reasonable and logical device for protection of exterior aircraft or other vulnerable surfaces 
from ice formation, wind, blowing sand or falling hailstones is a cover, designed from a combination 
of appropriate polymer materials. A new approach for such a cover could consist of an individual 
inflatable/deflatable blanket system of a design, configuration and size to completely cover exposed 
surfaces of flight vehicles, land vehicles and ground structures.  
The proposed solution design consists of three different layers (Figure 1). The bottom layer of 
the protective cover may be inflatable/deflatable with a layer of soft material suitable to protect an 
aircraft or other damage prone surfaces. The inner layer or layers of the cover could be designed so 
they have numerous individual air or fiber filled pockets within the structure as shock absorbing 
and/or temperature insulating layers. The number of rows and layers within is determined to protect 
an aircraft, vehicle or structure from damage from hail and other foreign objects striking it. The top 
layer of the cover includes a lightweight layer of highly reflective material to allow for greater 
protection in extreme heat environments such as the desert.  
 
 
 
 
Figure 1 General lay-up of multilayer protective cover design 
 
Bottom layer 
Top layer 
Inner layer 
4 
 
2.2 Objective 
This project is directed toward the creation of a polymer-fabric based flexible structure designed 
to protect aircraft, ground vehicles, and housing and storage structures in a wide range of naturally 
challenging or hostile environments from impact damage, thermal damage, and ice loading damage. 
The protective cover is designed and evaluated using different methods for their physical 
characteristics. 
This work also includes determining and testing a basic design to most effectively perform these 
and other requirements such as lightweight and low storage volume to stow the material in an 
aircraft or ground vehicle. It is also proposed to design the optimized device for easy deployment 
and adjustment when placing it over the aircraft, vehicle or ground unit.  
 
2.3 Effects of natural hazards in expected use 
Aircrafts, land vehicles and ground structures are exposed during short and long periods of time 
to different natural hazards.  Figure 2, depicts the effects that natural hazards pose on such 
structures. 
 
 
 
 
 
 
 
 
 
5 
 
 
 
 
 
 
 
 
 
 
 
Figure 2 Cause ? Effect tree 
 
2.3.1 Sun and heat 
Long term exposure of flight and land vehicles to ultraviolet rays from the sun deteriorates 
various vehicle parts.  For example, the various parts capable of being degraded are painted surfaces, 
glass, Plexiglass, and exterior appendages such as antennas, lights and lenses.  
The thermal expansion of metals, composite materials, and other materials changes a surface?s 
dimensions during elevated temperature exposure during long or short periods of time.  The surface 
also changes from the cycles of elevated and lowered temperatures, such as the changes that occur in 
the materials between daytime and nighttime exposure. By this, thermal damage introduces stress to 
the exterior material, fades the paint, and reduces its integrity; therefore, the long term value of the 
vehicles decreases.   
 
 
OBJECTIVE 
Opportunities for 
accident, injury 
and death Time consuming 
Expensive cost of repair 
and replacement 
Value of vehicle 
Heat Bird and animal nest Sand 
Wind 
Freezing rain Frost 
Ice 
Snow 
 
Rain & fuel contamination Thunderstorms Hail Sun 
Abrasion 
Hail damage 
Change in the 
aerodynamics 
UV deterioration Deterioration 
and damage of 
sophisticated 
equipment 
Ignition of 
nesting material Poor lift in take off 
Damage to 
the control 
mechanisms 
6 
 
2.3.2 Bird and animal nests 
Deterioration and corrosion of painted surfaces and external materials can be caused by bird 
droppings and nests. Since an airplane?s turbine is a weather protected unit, birds sometimes build 
nests inside this part.  As a result, it is possible to ignite the bird?s nest when the engine is started, 
thus causing a fire.  
 
2.3.3 Blowing sand 
Wear and scratches on the painted surfaces may be present by the effect of sand particles that 
are transported under blowing air conditions. It is similar to the process of sandblasting but at low 
velocities in which this abrasion can create oxidation on the surface. This incurs increased cost of 
maintenance caused by the accelerated aging and the devaluation of the vehicle. 
 
2.3.4 Freezing rain, frost, ice and snow 
These critical environmental hazards for aircrafts can cause serious accidents even if the aircraft 
has no mechanical problems or airframe damage. Parked aircrafts are exposed to weather conditions 
such as extreme cold and freezing rain leading to the formation of frost, snow, and ice on the lifting 
surface of the airplane. Accident history shows that takeoff accidents have been related to ice 
contamination as the probable origin or causal factor. A reduction of the lift and an increase of the 
drag are caused by these large accretions [1]. It is extremely costly and time consuming to remove, 
and public deicing facilities are not available in all airports. 
 
2.3.5 Thunderstorms and rain 
Heavy rainfall may introduce the possibility of water leaking past the fuel filler caps and then the 
fuel tank. In consequence of this, the engine and other components such as the fuel filter and the 
7 
 
carburetor bowl might not work properly. Catastrophic results can occur from rain water 
contamination. 
 
2.3.6 Thunderstorms and hail 
Thunderstorms accompanied by torrential amounts of hail could cause damage to the 
windscreen and the exterior of a vehicle, such as the formation of hail dimples. Damage from 
hailstones may affect the aerodynamics of aircrafts creating opportunities for accident, injury and 
death. Also, other navigational components for safe flights may be impacted. Body panels of truck 
trailers and automobiles which were parked outdoors are also exposed to hail damage (Figure 3). 
The cost of replacement or repair combined with the cost of the airplane out of commission is 
expensive. Impact of a large mass falling at low velocity on composites? surfaces may cause non-
visible manifestations of impact damage, such as internal delamination, which carry a significant loss 
of strength or stiffness of the components [2]. 
 
    
Figure 3 Vehicle damage caused by hail   
 
The following sections present a study of the specific weathering effects caused by natural 
hazards on the outdoor protective covers.  
8 
 
2.4 Deterioration of polymers 
Deterioration of polymers could occur as a result of exposure to heat, mechanical action, 
ultrasonic and sonic energy, radiation, electrical action in the form of dielectric effects, and chemical 
effects [3]. Polymer deterioration in the cover yields lower the mechanical properties; therefore, the 
outdoor cover must be designed to withstand each of these effects. 
 
2.4.1 Sun (UV and IR radiation) 
There are different gaseous constituents of the earth?s atmosphere which modify and attenuate 
light irregularly.  Solar energy is released in the form of ultraviolet waves, visible light waves, and 
infrared waves (Figure 4).  Within the solar spectrum range, the ultraviolet (UV) and infrared (IR) 
light regions yield more damage on structures than light from the visible range. Despite the fact that 
UV radiation is so destructive to structures, it only accounts for 6% of the solar radiation in the 
wavelength range below 400 nm. Non-visible radiation is around 42% in the wavelength range 
above 800 nm, while visible radiation accounts for 52% of total radiation and ranges from 400-800 
nm [4].  
 
 
Figure 4 Electromagnetic spectrum [5] 
9 
 
The principal reactions and interactions of solar radiation in polymeric materials are described in 
Figure 5. The major degradation process occurs from exposure of the polymer matrix to ultraviolet 
radiation due to the greater quantum energy.  Secondary processes of degradation result from 
thermal energy heating the sample when visible and IR radiation are absorbed by the material.  This 
thermal energy accelerates the aging process for the material [6].    
 
 
Figure 5 Principal reactions and interactions of solar radiation in polymeric materials [6] 
 
A wide variety of chemical reactions and physical processes occur when macromolecules are 
exposed for extended time periods to outdoors conditions, involving UV radiation, temperature 
variations and frequent changes in humidity. The stabilization of polymers against weathering 
damage entails the retardation or elimination of primary photochemical processes. The degradation 
of the polymer?s molecular weight may result from scission of the ketone carbonyl group located in 
the main chain or on the adjacent carbon in a sidechain [7].  
10 
 
Figure 6 illustrate the UV degradation of polyethylene. There is a direct correlation between the 
decrease in the physical properties of the polyethylene and the increase in the oxygen content caused 
by photodegradation.  
 
Figure 6 Degradation of PE caused by UV radiation [7] 
 
This degradation makes the materials more vulnerable to stress fatigue causing fractures such as 
microcracks; therefore, the material loses its mechanical performance. Discoloration, erosion, 
embrittlement,  and reduction in light transmission are other consequences of UV radiation [8].  In 
order to identify and measure the changes in the properties of polymeric materials, several standard 
test methods are available. These changes represent a valid situation of normal service life 
conditions. 
UV fluorescent lamps, open-flame carbon arc lamps, or Xenon arc lamps with different energy 
outputs and humidity conditions are common artificial weathering test equipment used for 
simulating polymeric materials exposed to solar radiation. The obtained values of these standard 
tests are spectral irradiance, which is the quantity of radiant flux striking a surface (W/m2?nm), and 
the radian exposure, which is the amount of irradiance acting upon the surface for a period of time 
(J/m2) [6].  
11 
 
Some specific properties of the material such as the absorption ratio or the thermal conductivity 
would influence the temperature increase on the irradiated surface.  Ovens are used to compare the 
change in a defined property or properties of a polymeric material produced by the exposure of this 
material to different temperatures for a number of exposure times. Original test results such as 
tensile strength, elongation, and hardness can be compared with the measured results obtained after 
the exposure of the material to a variation of temperature [6].   
A thermal insulation covering is required on the external surface of aircrafts and vehicles to 
maintain a stable inside temperature. The market offers canvas covers that lie over the windows and 
are attached to the outside of vehicles or smaller aircraft in an attempt to restrict the sun from 
entering the cockpit. This application appears to be marginally effective at best.  Also, there are 
custom fit reflective materials that are installed in the inside window openings of an aircraft or 
vehicle.  Since the reflective material is on the inside of the Plexiglass window, a great deal of heat 
builds up between the actual reflective material and the inside of the window or Plexiglass.  As a 
result, this causes great stress to the window or Plexiglass and reduces its life-span. 
 
2.4.2 Blowing sand 
Blowing air with sand particles may affect the friction and wear behavior of polymeric materials 
[9].  A layer of sand or dust may separate material from the cover material surface while it is exposed 
to air-sand condition; therefore resistance to abrasion is an important requirement for this 
application.  Resistance to abrasion is the ability of a material to resist the removal of material pieces 
from its surface when it is in contact with or rubbing against another surface [10].   
There are standard test methods for the determination of abrasion resistance in materials such as 
textile fabrics and plastics using different apparatus.  For example, the equipment utilized for this 
12 
 
testing method are a flexing and abrasion tester, rotary platform double head abrader, and loose 
abrasive abrading machine.  
These standard test methods are not directly applicable to this research due to the different 
failure criteria of the utilized materials for the end-use. As well, the type of material being tested for 
this application does not conform to the testing standards; the material is not a transparent plastic. 
These standards determine the abrasion resistance as a function of the breaking load, volume loss, 
and weight loss. Textiles fabrics, flat plastics, and transparent plastics are tested. Some procedures 
will be combined in order to find the abrasion failure criteria of this experiment that not only 
involves weight loss but detachments of the coating which can cause a change of the reflectance.  
 
2.4.3 Thunderstorms and rain 
Water may cause material failure by contributing to a loss in stiffness, an increase in creep, and 
stress relaxation. Mechanical stressing, swelling, and contraction of the polymeric material caused by 
water occur when the material is exposed to water or absorbs moisture from humid outdoor 
conditions. When the polymer absorbs water, it causes swelling of the material or washes away 
coatings and additives. During the absorption of water, compressive stresses are imposed 
superficially, and inside the material, tensile stresses are predominant.  A volume contraction appears 
when the surface is exposed to a dry period which dries off the surface layers while the core layers 
are still swollen. Therefore, it creates compressive stresses in the interior and tensile stresses on the 
exterior surfaces. As a result of the tensile forces on the exterior surface, cracking of the material 
surface may occur.  Also, as a consequence of this, the material?s dielectric properties, dimensions 
and appearance would be change [4].   
Solar radiation and rain water or dew are a combination of weathering processes which may 
accelerate failure due to the photochemical ageing process that induces embrittlement of the 
13 
 
polymeric material [4]. Therefore in order to evaluate the effect of water in the material, the same 
test methods are used as outlined previously for the simulation of sunlight exposure with the use of 
UV fluorescent lamps, carbon or Xenon arc lamps. 
 
2.4.4 Freezing rain, frost, ice and snow 
The protective cover is important for elimination of ice on the outside surface of an aircraft or 
vehicle while it is parked. However, snow, frost, and ice are capable of accumulating on the surfaces 
of polymeric material. The performance of the material at low temperatures may decrease due to a 
reduction in the flexibility and mobility of polymer chains. At low temperatures, the polymeric 
material can become brittle and rigid; the modulus of the material increases, therefore the elongation 
and the impact strength, which depends on the degree of crystallinity of the polymer, may decrease. 
As soon as the brittle failure starts, the crack will propagate with a small amount of load without 
noticeable deformation of the polymeric material [10].  
A standard test method, ASTM D746, for calculating the brittleness temperature of plastic and 
elastomers by means of impact is used for research and development purposes on applications in 
which the conditions of deformation are similar to those specified in the test.  Brittleness 
temperature can also be defined as the temperature at which 50% of tested samples have brittle 
failure under specified impact conditions.  However, brittleness temperature is often a useless 
parameter since the data obtained by testing under these specified conditions rarely matches the 
actual material?s conditions during application. [10].    
 
 
 
 
14 
 
2.4.5 Thunderstorms and hail 
Falling hailstones  
A hailstone is a single collection of ice that is formed during cycles of updrafts and downdrafts 
within a thunderstorm that contains water droplets and ice crystal frozen particles. The cycles of 
updrafts and downdrafts within a cloud cause the growing of the hail while it accumulates ice 
particles creating a layered structure. Larger hail is formed during severe thunderstorms when 
stronger updrafts are necessary [11]. 
 
Hailstone mass and geometry 
Hailstones may grow from 0.2 inch (pea size) to 7 inch (volleyball size). Typically, hail is around 
0.4-1.2 inches (nickel size) in diameter. There are reports of hailstones with 6 inch diameters and 
weighing 1.5 pounds which occurred in July of 1928 near Potter, Nebraska.  As well, in Coffeyville, 
Kansas on September 3, 1970 hailstones with a diameter of 6.5 inches and 1.3 pounds were recorded 
[12].  
Previous research concluded that the hailstone geometry is spherical or nearly spherical in large 
size hail [13], and reported hail densities are between 0.7 and 0.91 gm/cm3. Matson and Huggins 
classified spherical hailstones when they photographed more than 600 of them. [14].   
The mass of hail can be calculated using the following equations: 
              
     
Where:  
r = radius of the hail 
V= volume of a sphere  
15 
 
?= density of hail 
m = mass 
 
Table 1 summarizes the approximate mass of hail with a density of 0.91gr/cm3 based on the 
diameter size of hail stones formed.  
 
Table 1 Mass calculations of hailstones 
Diameter Radius Volume Mass 
in Cm cm cm3 gr 
1/4 0.64 0.318 0.13 0.12 
1/2 1.27 0.635 1.07 1.00 
3/4 1.91 0.953 3.62 3.29 
1 2.54 1.270 8.58 8.20 
1 1/4 3.18 1.588 16.76 15.25 
1 1/2 3.81 1.905 28.96 26.35 
1 3/4 4.45 2.223 45.98 41.85 
2 5.08 2.540 68.64 66.40 
2 1/4 5.72 2.858 97.73 88.94 
 
Hail impact 
The resulting damage for hail impact has been categorized at different levels according to the 
diameter, and it depends on the hail ice properties as well as the falling speed and wind speed. Hail 
with diameters from 5 to 20 mm may yield minor damage in vegetation and plants. Hail from 21 to 
40 mm diameter causes severe damage in glass and plastic structures, and vehicle bodywork. 
Significant risk of injuries, severe roof damage, and bodywork damage in grounded aircraft are 
caused by hailstone with diameters higher than 41 mm [15].   
Ice properties change depending on the temperature of ice formation. At a low velocity, the 
internal crystallinity of the ice has an effect on the relationship of force-time history and resulting 
16 
 
stress-strain curves [16] . The modulus and the modes of failure in ice can vary from ductile to brittle 
fractures. 
 
 
Figure 7 Modes of failure in ice as a function of strain rate [17] 
 
Schulson [17] explained the ice behavior and its dependency on deformation rate. Ice is ductile 
at low deformation rates and brittle at high rates. Schulson characterized ice for NASA with 
different compressive strengths from 6.1MPa in columnar structures to 14.8 MPa for single crystals. 
The transition takes place around the order of 10-3 s-1. Haynes [18] concluded that over -10?C the 
compressive strength of ices is between 5-25 MPa. In the temperature range -10 to -20?C the mean 
is 1.43 MPa. The effect of temperature on the tensile and compressive strength is inversely 
proportional, being higher in compression than in tension. Petrovic [19] summarized information 
collected from other researchers with reference to the effect of grain size and volume in the 
properties of ice. When the grain size increases, the tensile strength decreases. Additionally, the 
tensile strength of ice decreases with increasing the volume of the ice.  
17 
 
The elastic modulus and Poisson?s ratio of ice were measured by Gold [20] at temperatures of -
10?C and were reported in the range of 9.7 - 11.2 GPa and 0.29 - 0.32 respectively. Schroeder and 
McMaster [21] described the phase change of ice at -10?C from solid to liquid. Pressures around 
23.5 GPa are needed in order to generate a phase change. For ice impact applications, 23.5GPa is an 
extremely large pressure. Thus, ice impact can be connected with solid-body impact phenomena.  
 
Impact velocity 
During his tests, Gokhale found that the hailstones with diameters of 100 mm fall at a terminal 
velocity of nearly 30 m/s [22]. Ross and Carte [23] established that terminal speeds and the impact 
speeds of hailstones falling in air with the same mass can be found by the following equation: 
            
Where  
vo = terminal speed 
Dice = diameter of ice 
 
The density of the air used in that research was of 10-3 g/cm3 and the ice density of 0.89 ?0.05 
g/cm3. This equation presents a direct relationship between the terminal velocity and the diameter 
of the ice.  
Matson and Huggins [14] also studied the connection between the diameter of  hailstones and 
their kinematics. They concluded in their research that the vertical velocities of hailstones close to 
the surface (air density is equal to 9.93 x 10-4 g/cm3) can be predicted by:   
                  
18 
 
for a drag coefficient of 0.87 and Reynolds numbers from 103 to 2 x 104, where diameter of the 
ice is in centimeters. 
Theoretically, the force of drag, in fluid dynamics, is:  
            
Where: 
CD= drag coefficient 
A = cross sectional area of the hailstone 
? = air density 
v= velocity 
 
An initial condition is that the force is equal to the mass of the hailstone times the acceleration 
of gravity. Therefore, the terminal velocity can be calculated theoretically with the following 
expression: 
         
 
 
   
 
For spherical hail, the equation can be resumed in: 
            
     
 
   
         
Drag coefficient can be inferred, although it is not an exact figure due to velocity variation. By 
assuming that the fall speed is the terminal velocity and that it has a circular cross sectional area, the 
following expression is valid: 
              
      
 
19 
 
 Lazowski [24] and Bettie [25] determined the relationship               . The drag coefficient 
was inferred to be 0.61 at sea level. 
 Table 2 and Figure 8 show a comparison of the terminal speed of those models for hailstone 
with ice density of 0.89 g/cm3, air density 1.23 x 10-3 g/cm3, and drag coefficient of 0.6.  
 
Table 2 Analytical comparison of terminal speed models 
Ice 
Diameter 
 (mm) 
Terminal speed                                                                                                                                                    
(m/s) 
Ross - Carte Lazowski - Bettie Matson - Huggins 
 
 
 
 
4 7.842 7.861 7.242 7.939 
6 9.605 9.628 8.869 9.724 
11 13.005 13.037 12.009 13.166 
16 15.685 15.723 14.483 15.878 
21 17.969 18.013 16.593 18.191 
30 21.477 21.529 19.832 21.743 
40 24.800 24.860 22.900 25.106 
57.15 29.644 29.715 27.372 30.009 
63.50 31.247 31.323 28.853 31.986 
 
  =124  ???   = 12.43  ??1 2    = 11.45  ???   =  4 ???  3 ??    1 2  ??? 1 2  
20 
 
 
Figure 8 Analytical comparison of terminal speed models 
 
Kinetic energy 
Kinetic energy is a significant factor used to validate design criteria. The law of conservation of 
energy states that potential energy  (PE) before an event must equal the kinetic energy (KE) after an 
event [26].  
      
  ?         
Where:  
m = mass 
h = drop height  
g = acceleration of gravity 
v = velocity at impact 
 
21 
 
The net work (Wnet) required to stop an object in movement is equal to its kinetic energy. 
During an impact, the change in kinetic energy is equal to the average force of impact times the 
distance traveled for the object. This leads to the work-energy equation: 
                            
In a drop test, the initial velocity (        ) is equal to zero, therefore                .  
 
Impact angle 
Impact angle has a significant influence on the kinetic energy, as the resultant velocity increases 
with respect to the angle of the surface. Wind changes the falling direction of a hailstone from a 
vertical falling path to form a new trajectory impact angle ? as shown in Figure 9, that is equal to the 
arctan w/vo, where w is the wind speed.  The impact speed is               . 
 
   
Figure 9 Resultant impact speed at ? 
 
Table 3 shows the results of hail of an impact resistant test method for roof coverings in targets 
at 45? and 90? angles [27].     
 
 
22 
 
Table 3 Resultant velocity and kinetic energy of hailstones at 45? angle and free-fall [26] 
Diameter 
nom. Weight 
Terminal 
Free-Fall 
Velocity 
Resultant 
Velocity 
45o Angle 
Kinetic Energy     
in  g lb  ft/sec  ft/sec 
ft-lb     
Free-
Fall 
ft-lb     
45o Angle 
1 7.85 0.0174 73 103 1.43 2.57 
1.5 26.5 0.0588 90 127 7.35 14.72 
2 62.81 0.1394 105 148 23.71 47.49 
2.5 122.67 0.2723 117 165 57.48 115.17 
3 211.98 0.4705 130 183 122.55 245.70 
 
Impact energy  
Impact testing is performed to determine the energy absorbed and corroborate designs to 
guarantee the product?s durability and safety requirements. The total energy is conserved while no 
other external factors are present during the impact event; hence, the kinetic energy absorbed by the 
surface during a hail impact event can be calculated by  
                      
Laurie [28] analyzed the data collected by Bilham and Relf [29]  in prior research in Table 4 
related to hail sizes, terminal velocity, and impact energy.  
 
 
 
 
 
 
 
23 
 
Table 4 Terminal velocities and energies of hailstones [28] 
Diameter  Terminal Velocity  Approximate Impact Energy 
inches  cm ft/s mi/hr  m/sec ft-lb Joules 
1 2.5 73 50 22.3 < 1  <1.36 
1-1/4 3.2 82 56 25.0 4 5.4 
1-1/2 3.8 90 61 27.4 8 10.9 
1-3/4 4.5 97 66 29.6 14 19.0 
2 5.1 105 72 32.0 22 29.8 
2-1/2 6.4 117 80 35.7 53 71.9 
2-3/4 7.0 124 85 37.8 81 109.8 
3 7.6 130 88 39.6 120 162.7 
 
Different impact standard test methods were performed for roof covering and membranes 
concluding that there are significant variations in the procedure, and also in the results [27]. The 
following table, Table 5, presents the kinetic energies of the ASTM, FMRC and UL methods. 
 
Table 5 Kinetic energies produced by ASTM, FM, and UL standards test methods [27] 
Standard 
Missile Parameters 
Diameter            
in (mm) 
Mass               
lb (kg) 
Distance                   
ft  (mm) 
Energy                  
ft-lb (J) 
ASTM D3746 2 (50) (2.27) 4'5" (1355) 22 (30) 
FM Class I-SH 1.75 (45) (0.360) 17' 9.5" (5400) 14 (19) 
FM Class I-SH 2 (51) (0.737) 5 (1500) 8 (10.8) 
UL Class 1 1.25 (32) 0.28 (0.127) 12 (3700) 3.36 (4.6) 
UL Class 2 1.5 (38) 0.48 (0.218) 15 (4600) 7.2 (9.8) 
UL Class 3 1.75 (46) 0.79 (0.358) 17 (5200) 13.43 (18.3) 
UL Class 4 2 (51) 1.15 (0.521) 20 (6100) 23 (31.2) 
 
Under windy conditions the kinetic energy can be determined by  
                    
 
        
24 
 
Ross [23] deduced that the kinetic energy of hailstones can be determined with the following 
expression: 
                 ?   
      
       
The resulting kinetic energies from this equation are presented below in Table 6. 
 
Table 6 Kinetic energy of hailstones using Ross? equation 
Ice 
diameter 
(mm) 
Kinetic energy           
(J) 
Kinetic energy                   
(J) 
wind speed = 0 m/s wind speed = 17.5 m/s 
25.4 1.51 2.01 
31.8 3.68 4.90 
38.1 7.63 10.17 
44.5 14.13 18.84 
50.8 24.11 32.14 
63.5 58.86 78.48 
69.9 86.17 114.90 
76.2 122.05 162.73 
 
Impact behavior in material 
Metallic impactors such as steel balls or steel darts in impact test methods can be used to equate 
the impact energy to the kinetic energy of the ice in the form of hail. Nevertheless, when ice spheres 
hit a surface such as concrete tile, the ice compresses and crushes upon impact because the surface is 
much harder. Under the same conditions but using steel balls the concrete tile will fail. Ice spheres 
and steel balls will have the same impact energy, but the impact failure will be different. These test 
methods do not always replicate the hail resistance of the material [27]. Experimental, analytical 
solutions, and simulations conducted in explicit codes via FEA are founded for sphere impact 
against composited panels or metal surfaces.   
25 
 
The following figure, Figure 10, shows a representation of the sphere impact simulation based 
on the equation of motion of a single degree of freedom system due to the indentation and 
geometrical nonlinearities are neglected [30] .  
 
 
Figure 10 Quasi?static hail impact characterization spring-mass model 
 
M1 = mass of ice 
M2 = mass of material 
k1 and c1 correspond to the interaction ice-panel, where k1 could be nonlinear 
k2 and c2 correspond to the stiffness of the supporting panel 
F(t) = Impact force  
 
Some of the parameters for the above model are known or can be determined by physical 
measurement or numerical simulation. Because the function that describes the contact force which 
produces an indentation in nonlinear, this model does not provide a rigorous description of the 
impact event and outcome.  
M 1
M 2
v o
F( t)
x 1
0
c 1 k 1
x 2
0
c 2 k 2
F( t)
v o
Im p a c tM 1
M 2
26 
 
Olsson [31, 32] concluded in his research that the impact response type is related with the 
impactor and the plate mass rather than impact velocity. He also stated that impact velocity only 
influences the deflection amplitude.  Figure 11 represents the structural model of a composite panel 
under small mass impact.    
 
Figure 11 Structural model during small mass impact on plates [32] 
 
Fischer-Cripps [33] analyzed the relationship between elastic contact surfaces during an impact. 
Figure 12 represents a sphere impacting on a flat specimen. Following the law of the conservation of 
momentum and the Hertz contact equations, Fischer-Cripps deduced the equation for the impact 
load that can be used to determine the stress field and displacement:  
       
   
  
        
   
 
Where: 
P = maximum load 
m = mass of sphere 
vo = sphere velocity 
E* = the combined modulus of the sphere and the specimen given by Johnson [34] 
27 
 
 
   
      
  
       
   
Where: 
E = elastic modulus of the sphere 
? = Poisson?s ratio of the sphere 
E? = elastic modulus of the specimen 
?? = Poisson?s ratio of specimen 
 
 
Figure 12 Schematic of contact between two elastic solids (rigid, spherical indenter, and flat, 
non-rigid specimen) [35]    
 
The notations for Figure 12 are: 
u?z and uz are deformations.  
h is the distance between a point on the periphery of the sphere to the specimen surface. 
R? is the radius of the sphere. 
a is the radius of a circle of contact.  
? is the load-point displacement. 
28 
 
Kim and Welch [36] determined kinetic energy of a projectile using force transducers and strain 
gages for measuring the elastic response of the composite panels. Also they performed the test with 
increased velocities of the ice spheres; therefore, impact energies have slightly higher values for 
representing aerospace structures in flight. The goal of their research was to study the resulting 
damage on carbon/epoxy composites panels caused by impacts of ice projectiles. Jackson [2] 
remarked that the impact force that is developed for large-masses can be use as a key parameter in 
order to predict delamination damage formation on structures.  
Asp [37] compared the empirical methods of Kim [36] and the analytical models Olsson [32, 38] 
using Ultrasonic C-scan pictures and a laser displacement transducer. The result of Asp?s work 
determined that the empirical methods offer a close approximation of the damage resistance of 
composites for high velocity impacts (100 to 150 m/s).  Asp also determined that the analytical 
models are not satisfactory when ice impact is used against the non-crimp fabric composite plates.  
Other experiments [2] and standard test methods are used to analyze the impact of metallic 
indenters or spheres at low velocity on thick composite plates. Since all the proceeding work [2, 32, 
36-38] involves ice impacts at velocities much greater than 30 m/s on thick and hard composite 
surfaces, those experimental analyses cannot be applied for the designs assembled for the work in 
this research.   
 
Wave propagation 
The stress waves caused by the impact of a spherical object on a composite induce plastic 
deformation near the point of impact and elastic deformation in the surrounding area of the 
composite [39]. The stress waves travel from the front surface to rear surface and then return from 
the rear surface. Also, there is a reflected stress wave which goes through the spherical object 
29 
 
producing a fluctuation phenomenon [40]. Olsson [31, 32] related the response on composites plates 
impacted by hail with flexural waves and shear waves.  
 
 
Figure 13 Response during small mass impact on plates  [32] 
 
Researchers have studied impacts on composite fabrics using simulations with finite element 
methods. Nasr-Isfahani [41] compared his results with previous reported experiments observing that 
when a spherical object initially contacts a fabric or panel, the deformation wave is equal at the 
origin point of contact from the impact, and then the longitudinal waves propagates much faster 
than the transverse waves.  
Replication of experiments from relevant references is needed in order to extend the capabilities 
to specifically study the effects of hail damage in personal aircraft, vehicles, and ground structures.  
This investigation is intended to utilize the aforementioned information to evaluate and design more 
effective protective fabrics of various textile fabric configurations and plastic materials. 
At the present time, there is no work which represents any concept, product, application or 
process that completely or effectively addresses the safety and environmental hazards that expose 
the aircraft, vehicle, and ground unit to costly damage and serious injury and possible death as a 
30 
 
result of the damage imposed. For example, the exterior and interior of an aircraft are constructed 
with materials that are very susceptible to deterioration and damage from various environmental 
elements such as sun, heat, thunderstorms, hail, rain & fuel contamination, bird and animal nesting 
and droppings, freezing rain, frost, ice, snow, and extreme cold.  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
31 
 
 
 
 
 
 
 
3. EXPERIMENTAL DESIGN 
 
 
3.1 Materials  
Commercial polymer films and fabrics were used for this research. These materials were chosen 
as the best candidates for evaluating the physical properties that need to be studied in this project 
based on laboratory sampling of critical characteristics. The materials used for the experiments were:  
 
(a) TempShield? Single Bubble/Double Foil -  one layer of 5/32" barrier bubble film laminated 
between two layers of metalized film [42]. One of its reflecting sides has a circular embossing 
while the other side has triaxial embossing on the surface.  
(b) TempShield? Single Bubble/White Foil - one layer of 5/32" barrier bubble film laminated 
between one layer of metalized film and one layer of polyethylene [42]. 
(c) Super R Plus? - two-sided reflecting metalized film with polyester scrim reinforcement [42].  
(d) Temptrol? Heat Reflecting Fabric - polypropylene based non-woven perforated and 
metallized one side [42]. 
(e) 100% stitchbonded carbon fiber fabric. 
(f) 50% carbon fiber / 50% aramid (Kevlar? 49 brand) stitchbonded fabric. 
(g) Bubble wrap produced by IPS Packaging. 
(h) Polyethylene film 
 
The materials are shown in Figure 14. 
32 
 
               
 (a)                                                                     (b)     
                   
(c)                                                                     (d) 
                
(e)                                                                     (f) 
                
(g)                                                                     (h) 
Figure 14 Physical appearance of materials used in designs 
 
33 
 
The complete specifications and the applied methods of the material of Innovative Insulation 
Inc. are presented in Appendix A. 
 
3.2 Methodology to test the materials 
In order to find a methodology for a solution design, a cover for an aircraft such as Cessna 172 
with a wingspan of 11 m (36 ft 1 in), illustrated in Figure 15, is used to describe the layer 
requirements. The total plan of development and testing the cover design consists of two steps.  
 
Step 1: Characterization of layers 
In this step the individual layers were tested in order to identify their physical characteristics 
using different testing methodology standards according to the layer requirement. 
Outside layer requirements: 
1. Lightweight. 
2. Abrasion resistant. 
3. Low friction coefficient.  
4. Folding capability. 
5. Infrared/heat reflection.  
6. UV resistant.  
7. Impact resistant. 
8. Tear and puncture resistant. 
9. Burst resistant. 
 
34 
 
 
(a) Perspective view 
 
(b) Front view 
 
 
 
(c) Side view 
 
(d) Top view 
Figure 15 Depictions of multilayer protective cover design (units in inches) 
Reflection layer Insulation layer 
Static electricity dissipation layer 
35 
 
Inner layer requirements: 
1. Lightweight.  
2. Impact resistant.  
3. Burst/rupture resistant, also strength and elongation. 
 
Base layer requirement 
1. Lightweight. 
2. Static charge resistant. 
3. Flame resistant. 
4. Air permeability. 
 
The test results for each layer were organized and ranked in a matrix that permits a direct 
comparison between the expected use properties and the actual properties of the candidate 
materials. The selection of the materials is made based on the material with the highest sum.  
 
Step 2: Composite characteristics 
With the outcome information of Step 1, Step 2 consisted of creating two reasonable sample 
composites of vehicle and structure coverings which can serve to simulate the actual final form and 
construction of the composite. Afterward, the conglomerate composite structures were tested in 
order to determine if it still passed the impact absorption test. 
This step also determined feasible methods of forming and consolidating any or all of the 
proposed final structures and testing the fastening and consolidating points for possible tensile, 
reflectance and or pneumatic seal failure. 
 
36 
 
3.2.1 Areal density 
The protective cover has to be lightweight because it needs to be carried and stored easily either 
in the airplane or vehicle. By measuring each sample?s weight, dimension, and the knowing the area 
of the airplane, the total mass or areal density of the protective cover can be predicted depending on 
the material combinations being used.  
 
3.2.2 Abrasion test 
This test was conducted in order to evaluate the resistance of the outside layers to abrasion by 
measuring the weight loss. The abrasion testing was performed by using the ?Abraser? standard 
abrasion tester, Figure 16. The abrading wheels used in this test were CS-10 which have mild-
medium abrasive action for coatings, plastics, and textiles products. The load applied against the 
specimen was 500 g per wheel.  
The specimen of 4 in (102 mm) diameter was weighted using a digital balance. Then, the 
specimen was placed on the specimen holder and subjected it to the wear action of the two abrading 
wheels. The measurements of weight loss were made after 10, 25, 50 and 100 cycles of abrasion. A 
stereoscope was used for observing the removal of the metalized coating of the materials from its 
surface after the defined cycles of abrasion.   
 
37 
 
 
Figure 16 Abraser 
 
3.2.3 Friction test 
The friction test was used to measure the frictional properties of the outside layers when these 
layers undergo sliding contact with other surfaces. The specimen was clamped to the rectangular 
metal table that was mounted on the Instron testing machine as is shown in Figure 17. The 100 N 
load cell is connected to the sled weight (210 g) by a thin nylon rope. The aluminum sled was pulled 
at 150 mm/min across the material?s surface by the cross head. 
 
 
Figure 17 Friction test fixture 
38 
 
3.2.4 Folding test 
The folding endurance tester was used to determine the number of folds that the material would 
resist after rupture failure. The outside layer materials were tested in the folding endurance tester 
under a constant tension load of 1.5 kg. The specimens were held in jaws and then folded until 
cracks or ruptures occurred at the crease.  Due to the dimensional capacities of the available holding 
jaws, the inner and the base layers were not tested.   
 
 
Figure 18 Folding endurance tester 
 
3.2.5 UV resistance test 
The QUV accelerated weathering tester was used to evaluate UVA light of the outside layer 
materials. This test chamber apparatus reproduces damage caused by sunlight UV. The reflective 
side of each material faced the UVA 340 lamp for two weeks. After the requisite 14 days of 
irradiation, the samples were removed from the chamber. No measurements of irradiance or radiant 
exposure were made during the exposure. FTIR was used to identify changes in structure of the 
polymeric material during the exposure. A specimen of Single Bubble/Double foil was tested to 
observe impact properties changes. 
39 
 
 
Figure 19 QUV Weathering tester 
 
3.2.6 Impact resistance (impact test) 
The impact testing was performed by using the Instron Dynatup. This machine has a tup with a 
semi circular shaped end that is dropped onto the sample to be impacted. The tup is connected to 
the load cell by a weight of 2.3814 kg.  
 
 
Figure 20 Instron Dynatup 
40 
 
The total weight falling down to impact the samples was 2.7258 kg including the tup and tup 
bolt. It is evident that this weight was much higher than a typical hailstone. The samples used in this 
impact resistant test were the outside and inner layers. As shown in Figure 20 the sample was place 
in a frame that prevents rotation of the specimen.  
 
3.2.7 Tear resistance 
The tear resistance test was used to measure the tear propagation resistance of the outside layers 
when these experience a tear load. The specimen was secured to the grips where one grip was fixed 
and the other moved by the cross head at 250 mm/min.  The tear propagation test has been done 
on the Instron testing machine as shown in Figure 21.  
 
 
Figure 21 Tear test 
 
3.2.8 Bursting strength test 
The busting strength test was used to measure the bursting strength of the outside and inner 
layers to simulate what happens in the end use. The specimen was placed on the ring of the ball 
41 
 
burst attachment that was mounted on the Instron testing machine as is shown in Figure 22. A steel 
ball bursts the material when the specimen is pushed by the action of the cross head at 12 in/min  
 
 
Figure 22 Burst test 
 
3.2.9 Static charge resistance 
This innermost (or bottom layer) has to dissipate the static charge and inhibit electrical spark. 
Cold weather can exacerbate the occurrence of static discharge spark generation where certain 
polymeric materials are in contact with polymer film paints and where a high dielectric constant 
exists between the two surfaces. Removal of the vehicle or aircraft covers in those or similar 
conditions can cause a dangerous spark near fuel tanks that could result in an explosion. 
ASTM standards for measuring static dissipation and dielectric constants do not have relevant 
methodologies applied to this end use. A static measuring device (Voltmeter Isoprobe Model 244 
Monroe-electronics) provided by the department of Electrical Engineering (Auburn University) was 
used for testing of the inner (base) layer of the composite structure.  
42 
 
The prepared sample was attached to a buffer, and the buffer rubbed at high rpm against the 
painted and unpainted aircraft?s surface. Then, using an electrostatic voltmeter, the aircraft?s surfaces 
electrostatic charges were measured.  
 
 
Figure 23 Static test 
 
3.2.10 Flame resistance 
Samples were cut to 3 by 12 inches, and the exposed sample ends were covered with aluminum 
tape. The specimen was positioned vertically as shown in Figure 24. The flame was applied to the 
specimen for 12 seconds and then removed. The outside layers were tested to determine their 
response to an ignition source. The afterflame time was recorded as a characteristic of this test. 
 
              
Figure 24 Chamber flame resistant test 
43 
 
3.2.11 Air permeability 
Using the Frazier low differential pressure air permeability tester, the air permeability of the 
samples were obtained. The specimens of the base layer were placed on the specimen holder to 
create vacuum. Air is forced to pass through a nozzle with an orifice of 4 mm due to an applied 
suction from a motor.  
 
 
Figure 25 Frazier low differential pressure 
 
3.2.12 Hail impact simulation  
To test different designs and determine the impact resistance requirements from a combination 
of appropriate polymeric materials, an experimental test chamber was designed and constructed.  
The experimental set-up allows running test samples using ice projectiles instead of running test 
samples in drop weight testing machines where a steel penetrator is utilized. This equipment helped 
to simulate impact absorbing tests on materials with a closer approximation to the real events.  
44 
 
In order to test the sample composite covers, an experimental set-up was built and assembled. 
The following information is a description of the experimental set-up including specific technical 
details of the test equipment, instrumentations, and apparatuses.  
The test cabinet houses the illumination source and the frame where the target is fixed. A high 
speed camera is located outside the cabinet with a data acquisition system. A compressed air cannon 
launches an ice projectile to the target configurations. A schematic representation of the 
experimental set-up is shown in Figures 26 and 27. 
 
 
 
Figure 26 Experimental scheme set-up 
45 
 
 
Figure 27 Experimental set-up 
 
Compress air cannon  
The high velocity cannon (Figure 28) was made with schedule 40 PVC pipe and braid reinforced 
using a braiding machine. Multiples layers of fiber glass were applied over the reservoir. Polyester 
resin was applied along with resin transfer molding to infuse fiber to the resin matrix, and with this 
process a higher level of safety is achieved. An electro-valve is in line with the reservoir and barrel 
for the trigger mechanism; this system uses a solenoid to release pressure through the barrel. The 
system for aiming incorporates a fixed reservoir (Figure 29), and the barrel is minutely adjustable 
with a screw-type system in order to fine tune its accuracy. With this compressed air cannon it is 
only possible to fire single ice projectiles. 
46 
 
 
Figure 28 Compressed air cannon 
 
 
Figure 29 Air cannon fixture 
 
Test chamber 
A cabinet measuring 2 x 0.84 x 0.58 meters (Figure 30) was redesigned with two sections divided 
by a safety wall composite assembled of contact film, balsa wood and polystyrene foam. The first 
sectional area is where the  discarding sabot used to secure the ice is trapped by the wall to prevent a 
possible second impact from the sabot, and the second sectional area is where the final velocity is 
determined using a high speed camera. Impact and deformation measurements are logged upon 
47 
 
registration.  The test chamber shown in Figure 30 is mounted onto an aluminum frame shown in 
Figure 31. 
 
Figure 30 Test chamber 
 
In the second sectional area, there is an A36 steel frame with 349.25 x 349.25 mm dimensions 
which was manufactured to allow two mounting systems in two angles of incidence, 45? and 90?, as 
shown in Figure 32. The force transducer mounting system is aluminum square tubing, which 
mounts to the base frame; this holds the sensor base for attaching the force transducer.  The base 
frame is attached to the chassis of the test cabinet in a 90? angle with a stainless steel angle bracket. 
However in the 45? set-up, it is attached with A36 steel clamps with a horizontal spacing of 0.38 m. 
In addition, there are 1250 Watt halogen lights to provide appropriate illumination for the high 
speed camera. The high speed camera with a scale will record the impact event, and with this data, 
the terminal velocity can be determined.   
The test chamber was redesigned with gas shocks to provide an unattended open position of the 
doors for the new test set-ups. There are also inspection windows made of Plexiglass that allow 
quick and easy access during fine tuning equipment and test specimen replacement. There is a sliding 
door that prevents wind blast that may alter recorded velocities; also if there is discrepancy with the 
48 
 
path of the projectile in the first section, this will provide ricochet protection, and it allows access to 
the charging of ice projectiles diameters to the cannon.  
 
Figure 31 Experimental set-up frame 
 
                 
Figure 32 Targets at 45? and 90?  
 
Equipment Cabinet 
This cabinet is the housing for all electronic data logging components of the experimental set-
up, such as the signal conditioner model 482A21, computers, and power supply. The software 
49 
 
installed on the computer for data acquisition is Hot Shot SC, and the information collected will be 
simultaneously recorded for post-analysis. 
 
There are two kinds of experiments: 
? Ice impact force measurement for observing and measuring the parameters of ice 
such as diameter, velocity and kinetic energy.  
? Ice impact on the target for measuring the damage or failure of the value of 
impacting kinetic energy on polymer configuration.  
 
The camera is placed beside the test chamber, and both test configurations are recorded using 
the high speed camera NAC HotShot 512 SC, that has an attached Multi Channel Wave Inserter 
communicating via high speed serial IO port.  The collected data as a time waveform can be played 
in sequence with the image frame.  The camera can take up to 10,000 frames per second with a 
shutter time (exposure time) of 10 ?s in order to record the images of the impact event. The velocity 
of the impact was measured using the software HotShot SC Link and its measurement tools. To 
calibrate the image, the ?pixels per unit? are determined by selecting two points on a frame with a 
metric scale along the trajectory.  From knowing this value and tracking two interval positions along 
the flight path on the recorded images, the velocity is calculated.   
 
Ice impact force measurement  
Three different ice spheres diameters of 28.5, 40.5 and 57 mm (1.12, 1.59, 2.24 in) were formed 
to simulate hail in ice trays molds at -18?C (0?F). The densities of the ice spheres used in this 
experiment were roughly 0.94 gm/cm3.  
50 
 
Three different ice sphere structures were molded due to the absence of real hailstones, which 
have a similar spherical layer formation to that of an onion.  These three structures are shown in 
Figure 33. The monolithic ice construction was cast by filling the mold with water in one session. 
The layered ice construction was made in multiple events, approximately 10 layers, by pouring water 
in the mold. The cotton filler ice construction was prepared with cotton filler previously dipped in 
water and placed into the mold, and then the mold was filled with water. The layered ice and the ice 
sphere with cotton filler constructions were produced to simulate a tougher ice projectile than a 
monolithic sphere.   Table 7 indicates the weight proportion of cotton to ice according to diameter 
base on the standard test method F 320. 
 
 
Figure 33 Ice constructions 
 
 
 
51 
 
Table 7 Filler weight for each diameter 
 
 
The molds were placed in a refrigerator at -15 to -21?C (5 to -6 ?F).  The ice spheres were 
removed from the mold and stored in polyethylene bags and then placed back in a freezer. The ice 
sphere was taken out from the freezer approximately 3 minutes before the launch. During this 3 
minute period, the mass of the ice was recorded and put into a foam sabot. A foam sabot as shown 
in Figure 34 for each diameter was used to carry the ice projectiles. The ice spheres were launched 
from the compressed air cannon at different pressures in order to determine the impact velocity as is 
shown in Figure 35. The pressure was regulated by a valve just before the inlet of the pressure gauge, 
and then the ice projectiles were fired at the desired impact velocity. 
 
 
Figure 34 Foam sabot for varying diameter projectiles 
 
A comparison of the impact results was conducted in order to visualize any effect of the 
simulated ice constructions.   
D i a m e t e r  
( m m )
F i l l e r  w e i g h t                  
( g )
2 8 .5 0 1.37 ? 1.43
4 0 .5 0 3.86 ? 1.43
5 7 .0 0 10.83 ? 11.29
52 
 
 
Figure 35 Pressure vs. Velocity 
 
The initial ice impact force measurement is conducted with a dynamic force transducer (Figure 
36), a PCB model 200C50 with 50,000 lb (222.4 kN) compression rating, that has a stud where the 
ice impacts. The force transducer?s voltage output is transmitted to the BNC input jack on a sensor 
signal conditioner PCB model 482A21. The signal conditioner amplifies and filters the DC signals 
from noise and sends them to the Multi Channel Wave Inserter that is connected to the camera.   
Approximately 90 individual shots impacted against the force transducer at 90? angle and 40 at 
45? angle.  With this initial set-up, the recorded and observed data such as the ice size, velocity, and 
impact force are analyzed and quantified to provide appropriate parameters for the second part of 
the experiment.  
 
100 110 120 130 140 150 160
18
20
22
24
26
28
30
32
34
36
38
Vel
o
ci
t
y 
(m/
s)
Pressu re  (p si )
53 
 
                     
Figure 36 Force transducer set-up 
 
Ice impact on the target 
The second set-up is for composite material testing.  The testing apparatus has a square frame 
(Figure 37) which symmetrically clamps the specimen.  This provides a uniform compressive force 
along the perimeter of the tested material in order to prevent rotating, and allows in-plane freedom. 
Spherical ice projectiles of monolithic, layered and cotton filler constructions had three different 
diameters each (28.5, 40.5, and 57 mm).  Each kind of projectile was shot toward the composite 
target that is fixed in the A36 base frame which presents a free surface of 266.7 x 266.7 mm. The 
velocity ranged from 20 to 30 meters per second. The impact point is positioned at the center of the 
square surface material. Behind the material, a laser displacement sensor (SICK OD2-P30W04U0) is 
placed to 30 mm from the center with a measuring range of 26 to 34 mm with an accuracy of ?0.02 
mm. The response time of the displacement sensor is 3.5 ms with a resolution of 0.002 mm. Once 
the composite specimen was impacted, the deformation was measured at a pre-located point on the 
material during impact conditions. 
54 
 
                                    
Figure 37 Laser displacement transducer set-up 
 
The test targets that were evaluated included two sample composite configurations according to 
the results of the test in Step 1. Figure 38 shows the layer arrangement of each composite material 
tested.  
                         
 
                           
Figure 38 Composite target model detailing its composition 
Outside Layer 
 
Inner Layer 
 
Base Layer 
 
55 
 
The polyethylene film configuration in this experiment consisted of pumping air between the 
two films in order to create a cushion. Ten composite targets of each configuration were impacted. 
Each configuration was impacted by the launched ice projectiles of 28.5, 40.5 and 57 mm diameters.   
The ice spheres impacted the selected composite targets which were at 45? and 90? angles to the 
test target plane. At a 45? angle, the ice projectile?s kinetic energy increases considerably. This 
scenario simulates hail in an extreme wind.  Figure 39 shows the ice?s expected projectile path. 
 
 
 
Figure 39 Expected ice projectile path 
 
The frames of the composite center deflection time history were recorded using the high speed 
camera during the impact event.  
 
 
 
 
 
56 
 
 
 
4. EXPERIMENTAL RESULTS 
 
4.1 Areal density 
Table 8 summarizes the areal densities of each material. For the outside layer, the heat reflecting 
fabric has the lowest areal density while the single bubble/double foil has the highest value. Bubble 
wrap and carbon fiber fabric have the lowest areal density for the inner and base layers, respectively.  
 
Table 8 Areal density results 
  
 
After selecting the lowest values of areal density from each layer and then combining them, the 
weight of a cover design can be calculated.  For example, the wings of an aircraft such as Cessna 172 
with a wing area of 16.2 m2 (174 ft2) weighs 10.19 kilograms. The areal density results can be used 
when the final cover is defined with the rest of the properties.  
 
 
L a y e r M a t e r i a l
T h i c kn e s s     
( m m )
 A r e a         
(m
2
)
W e i g h t        
( g )
A r e a l  
d e n s i t y  
( g / m
2
)      
S i n g l e  B u b b l e / D o u b l e  F o i l 4 . 3 2 0 . 0 2 4 4 . 2 7 1 7 7 . 9 5
S i n g l e  B u b b l e / W h i t e  F o i l 3 . 2 4 0 . 0 2 4 3 . 7 9 1 5 5 . 4 7
He a t  R e f l e c t i n g  F a b r i c 0 . 3 9 0 . 0 2 2 2 . 1 1 9 6 . 3 4
T w o -s i d e d  F i l m  w i t h  P o l y e s t e r  S c r i m  
R e i n f o r c e m e n t
0 . 1 8 0 . 0 2 3 2 . 9 6 1 2 7 . 8 4
P o l y e t h y l e n e  F i l m 0 . 0 9 0 . 0 2 3 2 . 1 7 9 6 . 2 2
B u b b l e  W r a p 1 1 . 5 4 0 . 0 9 0 7 . 7 7 8 5 . 9 9
C a r b o n  F i b e r  F a b r i c 0 . 7 8 0 . 0 2 0 9 . 1 4 4 4 6 . 7 2
5 0 %  C a r b o n  F i b e r / 5 0 %  K e v l a r 1 . 3 3 0 . 0 3 4 1 7 . 0 8 5 0 4 . 4 0
O u t s i d e
B a s e
In n e r
57 
 
4.2 Abrasion test 
The weight loss for the 10, 25, 50 and 100 cycles of abrasion of the outside layers was reported 
in Table 9. As shown in Figure 40, it has been observed that the heat reflecting fabric has a better 
response to weight loss when it is exposed to an abrasive medium after 100 cycles. However, its 
performance after the first 10 cycles did not have good visual results. Table 10 presents a visual 
historic comparison of the wear abrasion.    
 
Table 9 Comparison of weight loss on samples after abrasion (g) 
  
 
 
Figure 40 Comparison of weight loss on samples after abrasion 
 
 
0 10 25 50 10 0
T w o -s i d e d  F i l m  w i t h  P o l y e s t e r  S c r i m  R e i n f o r c e m e n t 0 . 0 0 0 . 5 4 1 . 0 6 1 . 7 8 2 . 9 0
He a t  R e f l e c t i n g  F a b r i c 0 . 0 0 0 . 1 6 0 . 3 4 0 . 5 4 0 . 9 2
S i n g l e  B u b b l e / D o u b l e  F o i l  ( t r i a x i a l  e m b o s s i n g ) 0 . 0 0 0 . 4 2 1 . 0 6 1 . 7 6 2 . 6 6
S i n g l e  B u b b l e / D o u b l e  F o i l  ( c i r c u l a r  e m b o s s i n g ) 0 . 0 0 0 . 6 2 1 . 1 0 2 . 1 0 3 . 9 8
S i n g l e  B u b b l e / W h i t e  F o i l 0 . 0 0 0 . 5 2 0 . 9 2 1 . 4 4 2 . 6 0
C y c l e s
M a t e r i a l  
0 . 0 0
0 . 5 0
1 . 0 0
1 . 5 0
2 . 0 0
2 . 5 0
3 . 0 0
3 . 5 0
4 . 0 0
10 25 50 100
W
e
ig
h
t
 l
o
s
s
 (g
)
C y c l e s
H e a t  r e fle c t in g  fa b r ic
Sin g le  b u b b le /w h it e  fo il
Sin g le  b u b b le /d o u b le  fo il ( t r ia x ia l 
e m b o s s in g )
T w o - s id e d  film  w it h  p o ly e s t e r  s c r im  
r e in fo r c e m e n t
Sin g le  b u b b le /d o u b le  fo il ( c ir c u la r  
e m b o s s in g )
58 
 
Table 10 clearly illustrates the better performance of the two-sided film material and the double 
foil on both sides.  
 
Table 10 Visual comparison of wear abrasion on samples 
 
 
The heat reflecting fabric lost most of its reflecting coating after the 10th abrasion cycle. After 
the 50th cycle, the single bubble/white foil lost part of its metalized coating, and after the 100th cycle, 
it disappeared completely. The double foil material has better performance on the reflecting side 
with triaxial embossing. 
59 
 
4.3 Friction test 
The dynamic coefficient of friction was calculated with the average friction force divided by the 
sled weight. The static coefficient of friction was calculated with the first maximum peak force 
divided by the sled weight. As shown in Table 11, the best outside layer evaluation result of the 
dynamic and static coefficients of friction was for the two-sided reflecting film.   
 
Table 11 Friction test results 
  
 
4.4 Folding test 
No cracks or ruptures were observed in the samples materials after 1000 cycles, which likely 
represents more than the occurrence of folding during the life-span of the protective cover.  
 
4.5 UV resistance test 
After the exposure of the outside layer materials, no loss of gloss, fading, or craking were 
observed. As shown in Figure 40, there are two spectrums plotted for each exposed sample. The red 
color represents a control specimen and the blue color represents a test specimen. No molecular 
alterations or new peaks were observed in the heat reflecting fabric, Figure 41(b), when exposed to 
the ultraviolet ligth. In the two-sided film, Figure 42(a), there was an observation of a new peak at 
955.9 wavenumber, and this may be due to decompossition of the coating material. Diminishing of 
M a t e r i a l
A v e r a g e  f r i c t i o n  
f o r c e   ( In t e g r a l )  
( g f )
D y n a m i c  
C o e f f i c i e n t  o f  
F r i c t i o n
S t a t i c  C o e f f i c i e n t  
o f  F r i c t i o n
S i n g l e  B u b b l e / D o u b l e  F o i l  ( c i r c u l a r ) 3 6 . 4 0 0 . 1 7 0 . 2 2
S i n g l e  B u b b l e / D o u b l e  F o i l  ( t r i a x i a l ) 1 8 . 8 4 0 . 1 0 0 . 1 3
S i n g l e  B u b b l e / W h i t e  F o i l 5 0 . 7 5 0 . 2 4 0 . 3 3
T w o -s i d e d  R e f l e c t i n g  M e t a l i z e d  F i l m 1 0 . 5 2 0 . 0 5 0 . 0 9
He a t  R e f l e c t i n g  F a b r i c 1 7 . 5 1 0 . 0 9 0 . 1 2
60 
 
the peaks at 1078.5 and 1378.8 wavenumbers in the white foil material was observed, Figure 41(a), 
but the exact reasons for these changes were not identified. The intensity of a few peaks are 
observed to be high when compared to their control specimen in white foil and double foil samples. 
 
 
(a) Single Bubble/White Foil 
 
 
(b) Heat Reflecting Fabric 
Figure 41 FTIR spectra of the outside layers 
61 
 
 
(a) Two-sided Film with Polyester Scrim 
 
 
(d) Single Bubble/Double Foil 
Figure 42 FTIR spectra of the outside layers 
 
4.6 Impact resistance (impact test) 
Table 12 shows the results of the impact tests. As indicated graphically, the impact energy was 
similar for all the tests. The energies obtained from the impact tests were similar to hailstone impact 
of 1 to 1 ? in diameter.  Their energies were measured between 1.36 to 5.4 J. The outside material 
that exhibited a better impact response was the two-sided film. Polyethylene film had more than 
double the energy of the maximum load of the bubble wrap material.  
62 
 
Table 12 Impact test results 
 
 
4.7 Tear resistance 
From Table 13, it has been determined that the material that has the best tear strength is the two 
sided film, but with low extension at maximum load. This material has polyester scrim 
reinforcement which leads to more tear strength compare to the other materials. It was also 
observed that the double foil and white foil have high extension at maximum load due to the barrier 
bubble film. Double foil has uniform tear propagation resistance may be due to the metalized film 
on both sides.  
 
Table 13 Tear resistance test results 
 
 
 
 
L a y e r M a t e r i a l
M a x i m u m  
L o a d                
( N )
T i m e  t o  
m a x  l o a d -1               
( m s )
Im p a c t  
v e l o c i t y -1                   
( m / s )
T o t a l  
e n e r g y -1        
( J )
E n e r g y  t o  
m a x  l o a d -1            
( J )
T o t a l  t i m e -1              
( m s )
Im p a c t  
e n e r g y -1          
( J )
S i n g l e  B u b b l e / D o u b l e  F o i l 3 3 . 3 8 6 . 2 5 1 . 5 1 0 . 3 1 0 . 1 8 2 0 . 5 8 3 . 1 2
S i n g l e  B u b b l e / W h i t e  F o i l 1 2 0 . 8 8 9 . 9 0 1 . 5 1 0 . 8 9 0 . 8 3 1 2 . 0 4 3 . 1 2
He a t  R e f l e c t i n g  F a b r i c 8 6 . 8 2 8 . 7 7 1 . 5 2 0 . 5 6 0 . 5 2 9 . 3 7 3 . 1 7
T w o -s i d e d  F i l m  w i t h  P o l y e s t e r  S c r i m  2 6 2 . 2 4 9 . 2 1 1 . 5 1 1 . 3 4 1 . 2 8 9 . 5 3 3 . 1 2
P o l y e t h y l e n e  F i l m 1 2 5 . 8 3 8 . 5 3 1 . 5 2 0 . 7 8 0 . 7 0 1 2 . 8 8 3 . 1 3
B u b b l e  W r a p 3 3 . 6 0 9 . 3 5 1 . 5 3 0 . 3 0 0 . 2 7 1 7 . 3 1 3 . 2 1
O u t s i d e
In n e r
A v e r a g e  L o a d  
( In t e g r a l )         
( N )
F i r s t  P e a k ( L o a d  
10  %  C h a n g e )        
( N )
M a x i m u m  L o a d     
( N )
E x t e n s i o n  a t  
M a x i m u m  L o a d  
( m m )
1 2 . 6 2 1 8 . 1 3 1 8 . 1 3 7 7 . 1 7
1 2 . 6 2 1 6 . 8 5 1 8 . 4 2 6 0 . 2 5
1 2 . 3 7 1 8 . 9 6 1 9 . 0 9 3 9 . 6 7
1 8 . 3 9 2 3 . 5 6 2 7 . 4 2 2 7 . 2 5
M a t e r i a l
S i n g l e  B u b b l e / D o u b l e  F o i l
S i n g l e  B u b b l e / W h i t e  F o i l
He a t  R e f l e c t i n g  F a b r i c
T w o -s i d e d  F i l m  w i t h  P o l y e s t e r  S c r i m  
63 
 
4.8 Bursting strength resistance 
Table 14 summarizes the results of the test for bursting strength for the outside and inner layers. 
It has been observed that the two-sided film has almost double the bursting strength of the other   
outside materials tested. For the tested inner layers, it was found that bursting strengths were very 
close for both materials, but the extension at maximum load was double for the bubble wrap.  
 
Table 14 Burst resistance test results 
  
 
4.9 Static charge resistance 
Carbon fiber showed the results for high electrostatic discharge generation. The electrostatic 
discharge surface voltage generated using 50% carbon fiber/50% Kevlar produced less voltage than 
the pure carbon and Kevlar fabric for the two lowest rpm settings.  At higher rpm levels, the carbon 
fabric produces the least electrostatic charge. Kevlar generated electrostatic discharge surface voltage 
between volts.  
 
Table 15 Electrostatic charge of materials tested (volts or potential) 
 
L a y e r
M a x i m u m  L o a d                
( N )
E x t e n s i o n  a t  
M a x i m u m  L o a d           
( m m )
1 3 4 . 3 1 3 0 . 5 8
2 3 4 . 8 6 2 1 . 4 4
2 8 8 . 0 8 2 1 . 9 4
5 9 1 . 1 9 1 8 . 4 0
6 3 . 1 8 1 8 . 4 0
5 7 . 2 4 3 4 . 8 9
M a t e r i a l
P o l y e t h y l e n e  F i l m
B u b b l e  W r a p
O u t s i d e
In n e r
S i n g l e  B u b b l e / D o u b l e  F o i l
S i n g l e  B u b b l e / W h i t e  F o i l
He a t  R e f l e c t i n g  F a b r i c
T w o -s i d e d  F i l m  w i t h  P o l y e s t e r  S c r i m  
r p m 10 0 %  C a r b o n  F i b e r
5 0 %  C a r b o n  
F i b e r / 5 0 %  
K e v l a r
K e v l a r 10 0 %  C a r b o n  F i b e r
5 0 %  C a r b o n  
F i b e r / 5 0 %  
K e v l a r
K e v l a r
13 3 0 - 2 1 -8 - 2 5 - 1 7 -7 - 2 5
2330 - 2 2 - 2 0 - 2 8 - 2 2 - 1 9 - 2 6
2980 - 3 0 - 5 0 - 4 2 - 2 5 - 2 9 - 3 6
P a i n t e d  A i r c r a f t  A l u m i n u m  U n p a i n t e d  A i r c r a f t  A l u m i n u m
64 
 
4.10 Flame resistance 
The following are the observations for the samples tested:  
- Single bubble/white foil: burned completely  
- Single bubble/double foil: partially burned for about 5 seconds  
- Two-sided film with polyester scrim reinforcement: partially burned for about 4 seconds 
- Heat reflecting fabric: partially burned for about 7 seconds 
 
Figure 43 a-d shows the chronological flame test process of the material two-sided film with 
polyester scrim reinforcement.  Figure 44 shows the result after the sample has been flame tested.   
 
          
  (a)                                                         (b) 
                         
(c)                                                        (d) 
Figure 43 Test of flame resistance 
65 
 
 
Figure 44 Sample after test of flame resistance 
 
4.11 Air permeability 
The differential air pressure was recorded, and the flow/area for each base layer sample was 
determined.  According to a chart for a nozzle of 4 mm, both base layer fabrics as shown in Table 
16 have similar flow/area values. 
 
Table 16 Air permeability test 
  
 
After testing the individual layers? properties, the following material selection matrices were 
made as shown in tables 17 ? 19. The rating criteria were listed between 1 and 3. The rating score of 
1 means the property is optional, 2 is desirable, and 3 is a critical property. Each material is 
prioritized in comparison with the other material candidates; their rankings appear in the top cell of 
M a t e r i a l F l o w / A r e a  [ ( f t 3 / m i n ) / f t 2 ]
C a r b o n  F i b e r  F a b r i c 2 8 . 5 9
5 0 %  C a r b o n  F i b e r / 5 0 %  K e v l a r 3 0 . 6 6
66 
 
their rating matrix. The lowest ranking of 1 is assigned to the material with the least desirable 
property. The number in the bottom cell of the rating matrix for a specific property is the value of 
the rating times the rank of the material. Therefore, the most important property which was assigned 
the highest rating number is more influential on the overall material selection process. 
 
Table 17 Material selection matrix base layer 
 
 
Table 18 Material selection matrix inner layer 
 
 
 
E x p e c t e d  p r o p e r t i e s R a t i n g C a r b o n  F i b e r
5 0 %  C a r b o n  
F i b e r / 5 0 %  
K e v l a r
2 1
4 2
2 1
6 3
2 1
6 3
2 1
4 2
20 10
L i g h t w e i g h t
T o t a l
S t a t i c  c h a r g e  r e s i s t a n t
F l a m e  r e s i s t a n t
A i r  p e r m e a b i l i t y
2
3
3
2
E x p e c t e d  p r o p e r t i e s R a t i n g
P o l y e t h y l e n e  
F i l m
B u b b l e  W r a p
1 2
1 2
2 1
6 3
2 1
4 2
11 7T o t a l
L i g h t w e i g h t
Im p a c t  r e s i s t a n t
B u r s t  r e s i s t a n t
1
3
2
67 
 
Table 19 Material selection matrix outside layer 
 
 
The specimens were constructed using a two-sided film with polyester reinforcement as an outer 
layer, carbon fiber as a bottom and with two options to test for the inner layer using bubble wrap or 
using air inside the polyethylene film pushed by an air pump. 
 
4.12 Hail impact simulations 
Information regarding the hail impact simulations and a full description of the test conditions is 
found in section 3.2.12.  The output voltage signal from the force transducer and laser displacement 
transducer are plotted as a function of time as shown in Figure 45.  
 
E x p e c t e d  
p r o p e r t i e s
R a t i n g
S i n g l e  
B u b b l e / D o u b l e  
F o i l
S i n g l e  
B u b b l e / W h i t e  
F o i l
Hea t  R e f l e c t i n g  
F a b r i c  
T w o -s i d e d  F i l m  
P o l y e s t e r  
R e i n f o r c e m e n t
1 2 4 3
2 4 8 6
4 1 2 3
8 2 4 6
2 1 3 4
2 1 3 4
0 0 0 0
0 0 0 0
1 2 4 3
3 6 12 9
1 3 2 4
2 6 4 8
1 2 3 4
2 4 6 8
1 2 3 4
2 4 6 8
3 1 2 4
3 1 2 4
24 28 45 53T o t a l
1
L i g h t w e i g h t
A b r a s i o n  r e s i s t a n t
L o w  F r i c t i o n
F o l d i n g  c a p a b i l i t y
U V r e s i s t a n t
I m p a c t  r e s i s t a n t
T e a r  r e s i s t a n t
B u r s t  r e s i s t a n t
F l a m e  r e s i s t a n t
3
2
2
2
2
2
1
2
68 
 
 
Figure 45 Volts vs. time (output signal) 
 
Figures 46-48 depict the dynamic force history of 57, 40.5, and 28.5 mm ice projectiles, 
impacting the force transducer for the following velocities 29.5 m/s, 25.5 m/s and 21.5 m/s.  The 
peak force of the test data occurs in the first milliseconds of the impact event and varies in the 
magnitude of the peak force for the different projectile diameters. 
 
 
Figure 46 Peak force of layered ice (57 mm diameter) at 90? impact 
 
0 .0 0 0 0 0 .0 0 0 2 0 .0 0 0 4 0 .0 0 0 6 0 .0 0 0 8 0 .0 0 1 0
0 .5 5
0 .6 0
0 .6 5
0 .7 0
0 .7 5
0 .8 0
V
o
lt
a
g
e
 (
mV
)
T ime  ( s e c )
8.31 kN
69 
 
 
Figure 47 Peak force of layered ice (40.5 mm diameter) at 90? impact 
 
 
Figure 48 Peak force of layered ice (28.5 mm diameter) at 90? impact 
 
Figure 49 indicates that the peak force is directly proportional to the kinetic energy from all tests 
on the transducer. The plot in Figure 50 presents the voltage time history of an ice impact at 30 m/s. 
 
 
0.0000 0.0002 0.0004 0.0006 0.0008 0.0010
0.57
0.58
0.59
0.60
0.61
0.62
0.63
0.64
0.65
0.66 2.44 kN
V
o
lt
a
g
e
 (
mV
)
T ime  ( s e c )
0 .0 0 0 0 0 .0 0 0 2 0 .0 0 0 4 0 .0 0 0 6 0 .0 0 0 8 0 .0 0 1 0
0 .5 7 5
0 .5 8 0
0 .5 8 5
0 .5 9 0
0 .5 9 5
0 .6 0 0
0 .6 0 5 0.18 kN
V
o
lt
a
g
e
 (
mV
)
T ime  ( s e c )
70 
 
 
Figure 49 Peak force vs. Kinetic energy 
 
 
Figure 50 Summary of ice with cotton fillers (57 mm diameter) at 90? impact 
 
The impact event of a layered ice projectile was recorded with the high speed camera, and Figure 
51 shows the frames from the ice impacting the force transducer at 29.5 m/s.  At 0.08 ms the ice 
-1 0 0 10 20 30 40 50
0
2
4
6
8
Pea
k 
F
o
rce
 (kN
)
Ki n e t i c Ene rg y  (J)
71 
 
projectile begins to make contact with the transducer. At 0.1 ms the peak force occurs, as a very 
short duration impulse, and at 0.2 ms there is a complete dispersion of fragments of the ice 
projectile.  
 
 
Figure 51 Summary of layered ice (57 mm diameter) at 90? impact  
72 
 
Figures 52-54 depict the dynamic force history of 57, 40.5, and 28.5 mm ice projectiles 
impacting the force transducer for the following velocities 29.5 m/s, 25.5 m/s and 21.5 m/s with an 
incidence angle of 45 degrees.  The peak force of the test data has similar behavior to the 90 degree 
tests. Furthermore, a plausible explanation to this phenomenon lies in the effects of impact on load 
cell position, which are not in this research.    
 
  
Figure 52 Peak force of ice with cotton fillers (57 mm diameter) at 45? impact  
 
 
Figure 53 Peak force of ice with cotton fillers (40.5 mm diameter) at 45? impact 
0 .0 0 0 0 0 .0 0 0 2 0 .0 0 0 4 0 .0 0 0 6 0 .0 0 0 8 0 .0 0 1 0
0 .5 5
0 .6 0
0 .6 5
0 .7 0
0 .7 5
0 .8 0
0 .8 5
0 .9 0
Vol
ta
g
e
 (mV)
T i m e  (se c)
1 2 . 9 4  k N
0 .0 0 0 0 0 .0 0 0 2 0 .0 0 0 4 0 .0 0 0 6 0 .0 0 0 8 0 .0 0 1 0
0 .5 5
0 .6 0
0 .6 5
0 .7 0
0 .7 5
0 .8 0
8 . 4 2  k N
V
o
lt
a
g
e
 (
mV
)
T ime  ( s e c )
73 
 
  
Figure 54 Peak force of ice with cotton fillers (28.5 mm diameter) at 45? impact  
 
Information such as mass, velocity, and kinetic energy of some selected tests are consolidated in 
Table 20.   
Table 20 Test summary of ice constructions 
 
0 .0 0 0 2 0 .0 0 0 3 0 .0 0 0 4 0 .0 0 0 5 0 .0 0 0 6 0 .0 0 0 7 0 .0 0 0 8 0 .0 0 0 9 0 .0 0 1 0 0 .0 0 1 1
0 .5 8
0 .6 0
0 .6 2
0 .6 4
0 .6 6
0 .6 8
3 . 4 6  k N
V
o
lt
a
g
e
 (
mV
)
T ime  ( s e c )
D i a m e t e r M a s s Vel o c i t y E n e r g y P e a k  F o r c e
( m m ) ( g ) ( m / s ) ( J ) ( k N )
1 1 . 4 4 2 1 . 2 2 2 . 5 8 0 . 5 0
1 1 . 4 1 2 1 . 4 1 2 . 6 1 0 . 3 2
1 1 . 2 0 2 1 . 8 8 2 . 6 8 0 . 1 9
3 2 . 4 4 2 5 . 1 0 1 0 . 2 2 2 . 8 2
3 1 . 6 1 2 6 . 0 0 1 0 . 6 9 3 . 0 4
2 9 . 5 2 2 5 . 5 0 9 . 6 0 0 . 6 7
1 0 0 . 3 3 2 9 . 5 0 4 3 . 6 6 6 . 4 5
9 7 . 8 3 3 1 . 0 4 4 7 . 1 3 7 . 5 9
9 5 . 1 5 3 1 . 5 6 4 7 . 3 9 7 . 9 0
1 0 . 5 3 2 0 . 8 0 2 . 2 8 0 . 5 0
1 0 . 5 7 2 0 . 3 4 2 . 1 9 0 . 2 8
1 0 . 5 8 2 0 . 8 0 2 . 2 9 0 . 5 9
3 1 . 6 3 2 5 . 5 0 1 0 . 2 8 1 . 9 0
3 2 . 1 5 2 5 . 5 0 1 0 . 4 5 2 . 3 8
3 2 . 5 0 2 5 . 5 0 1 0 . 5 7 2 . 1 2
9 6 . 9 8 2 8 . 9 5 4 0 . 6 3 6 . 9 4
9 6 . 7 5 3 0 . 8 6 4 6 . 0 8 8 . 2 9
9 7 . 5 0 2 9 . 1 8 4 1 . 5 1 8 . 7 8
1 2 . 1 7 2 1 . 1 8 2 . 7 3 2 . 7 3
1 1 . 0 8 2 0 . 3 0 2 . 2 8 2 . 3 4
1 2 . 2 0 2 0 . 6 5 2 . 6 0 2 . 5 1
3 2 . 7 3 2 5 . 1 1 1 0 . 3 2 5 . 8 4
3 2 . 4 0 2 4 . 7 7 9 . 9 4 6 . 1 5
3 2 . 0 3 2 5 . 6 0 1 0 . 5 0 7 . 0 7
9 8 . 2 1 3 0 . 7 9 4 6 . 5 4 1 6 . 9 7
1 0 3 . 5 4 2 9 . 9 8 4 6 . 5 4 1 9 . 6 4
1 0 0 . 8 5 2 8 . 9 8 4 2 . 3 4 1 6 . 7 9
4 0 . 5 0
4 0 . 5 0
5 7 . 0 0
5 7 . 0 0
C o n s t r u c t i o n
M o n o l i t h i c 4 0 . 5 0
5 7 . 0 0
L a y e r e d
C o t t o n  f i l l e r s
2 8 . 5 0
2 8 . 5 0
2 8 . 5 0
74 
 
Figure 55 presents the plotted data for the test of monolithic, layered and cotton fillers simulated 
hail for all three diameters. The measured peak forces vary linearly with the kinetic energy of the ice 
projectile, and the slope of each line changes with the ice projectile diameter.  
 
 
Figure 55 Peak force vs. Kinetic energy for all ice construction projectiles 
 
Figure 56 compares the force history of all three constructions at 30 m/s showing almost no 
clear difference in the behavior during the impact event for the monolithic and layered ice 
projectiles. However, the ice projectile with cotton fillers shows a substantial increase in the peak 
force. 
 
 Figure 56 Comparison of force history all ice construction projectiles 
0 10 20 30 40 50
-2
0
2
4
6
8
10
12
14
16
18
 M o n o l i t h i c
 L a y e re d
 C o t t o n  f i l l e rs
 L i n e a r F i t  M o n o l i t h i c
 L i n e a r F i t  L a y e re d
 L i n e a r F i t  C o t t o n  f i l l e rs
Pe
a
k 
F
o
rce
 (KN
)
Ki n e t i c En e rg y  (J)0 .0 0 0 0 0 .0 0 0 2 0 .0 0 0 4 0 .0 0 0 6 0 .0 0 0 8 0 .0 0 1 0
0 .5 5
0 .6 0
0 .6 5
0 .7 0
0 .7 5
0 .8 0
0 .8 5
0 .9 0
0 .9 5
1 .0 0 1 6 . 8 2  k N
8 . 7 4  k N
V
o
lt
a
g
e
 (
MV
)
T ime  ( s e c )
 M o n o l i t h i c
 L a y e re d  
 C o t t o n  f i l l e rs
7 . 8 3  k N
75 
 
Table 21 presents the deformation caused by the three different diameter impacts for the 
combination of the three layers collected using the high speed camera.  
 
Table 21 Displacement in material 
 
 
Figures 57 and 58 show the composite center deflection history measured with the laser 
displacement transducer.  
Figure 57 is a plot of the displacement (y-axis) versus time (x-axis) of the base layer.  This sample 
includes an inflated polyethylene bladder as an inner layer.  From the plot we observe upon impact 
the base layer deflects to approximately -2.25 mm where it remains.   
 
 
 
  
P o l y e t h y l e n e  F i l m 3 0 . 9 8 1 2 6 . 7 2 . 0 0
P o l y e t h y l e n e  F i l m 3 2 . 1 2 1 2 7 . 3 2 . 2 5
B u b b l e  w ra p 3 1 . 7 2 1 2 6 . 6 1 3 . 2 4
P o l y e t h y l e n e  F i l m 3 0 . 8 5 1 2 6 . 8 3 . 5 0
P o l y e t h y l e n e  F i l m 2 9 . 7 3 1 2 7 . 3 3 . 5 0
B u b b l e  w ra p 3 0 . 1 5 1 2 7 . 8 1 4 . 5 4
P o l y e t h y l e n e  F i l m 3 2 . 1 7 1 2 6 . 5 1 . 5 0
P o l y e t h y l e n e  F i l m 3 3 . 3 3 1 2 5 . 9 2 . 2 5
B u b b l e  w ra p 3 3 . 8 7 1 2 6 . 4 1 7 . 8 9
P r e s s u r e    
( p s i )
D e f o r m a t i o n  
( m m )
M o n o l i t h i c
L a y e r e d
C o t t o n  f i l l e r s
C o n s t r u c t i o n In n e r  M a t e r i a l
M a s s       
( g )
76 
 
  
Figure 57 Composite material with polyethylene film impacted by an ice projectile with cotton 
fillers (40.5 mm) 
 
Figure 58 is a plot of the displacement (y-axis) versus time (x-axis) of the base layer.  This sample 
includes bubble wrap as an inner layer.  From the plot we observe, upon impact, the base layer 
deflects to approximately -18 mm and returns to the original position.  Final inspections indicate 
that the bubbles burst during the impact.   
 
 
Figure 58 Composite material with bubble wrap inner impacted by an ice projectile with cotton 
fillers (40.5 mm) coefficient  
0 .0 0 0 0 .0 0 1 0 .0 0 2 0 .0 0 3 0 .0 0 4
-2 .5
-2 .0
-1 .5
-1 .0
-0 .5
0 .0
D
isp
la
ce
me
n
t 
(mm)
T i m e  (se c)
-0 .0 0 1 0 .0 0 0 0 .0 0 1 0 .0 0 2 0 .0 0 3 0 .0 0 4 0 .0 0 5 0 .0 0 6 0 .0 0 7 0 .0 0 8
-2 0
-1 8
-1 6
-1 4
-1 2
-1 0
-8
-6
-4
-2
0
2
D
ispl
a
cem
e
n
t 
(mm)
T i m e  (se c)
77 
 
Figure 59 captures the specimen before, during, and after impact.  The projectile impacts, 
deforms, and is deflected by the test specimen in Figure 59.  The displacement data collected using 
the high speed camera and the laser displacement transducer have been verified to correlate well. 
 
 
Figure 59 Summary of deformation of composite specimen  
   
78 
 
Figure 60 presents a detailed monitoring of the deformation behavior for a composite panel 
impacted by an ice projectile of 57 mm at 30 m/s.  Figure 60 demonstrates how the integrity of the 
material is compromised when impacted by the largest hailstone (57 mm), revealing that this material 
is unsuitable for protection against impacts of such a large size and mass.  However, this material has 
been demonstrated to provide adequate protection against hail stones up to 46 mm in diameter.   
 
 
Figure 60 Sequence of the ice impact (57 mm diameter) on specimen 
 
 
 
 
 
 
 
 
 
 
79 
 
 
 
5. CONCLUSIONS 
 
An experimental impact enclosure for the study and analysis of impact events of polymeric 
materials has been developed.  The primary features of the designed, instrumented, experimental 
setup include data acquisition, image acquisition, high speed camera, image analysis, laser-based 
specimen deflection determination, force transducer, and electronically actuated compressed air 
cannon.  The compressed air cannon is reinforced with braided high strength glass fibers and epoxy 
resin for safety with moderate operating pressures.  Furthermore, the compressed air cannon barrel 
is made from PVC plastic and is easily adjustable, making it particularly suitable for ice and other 
large scale low speed projectiles.  These unique experimental capabilities provide information which 
can be used to determine the requirements for protective covering of vehicles and aircraft that will 
be exposed to hail impact.    
Based on the information obtained during the individual layer characterization experiments of 
chapter 4, low velocity impact tests were performed in the experimental test chamber on composite 
materials and polymeric films, using ice projectiles launched at velocities ranging from 20 to 30 
meters per second with incidence angles of 90? and 45?.  
 The results presented in chapter 4 demonstrate the relationship between displacement and 
damage on the composite material and the influence of various ice constructions is discussed.  
Additionally, a high speed camera with corresponding image analysis was conducted correlating the 
impact with time. The behavior observed during impact of the tested composite specimen exhibits 
peak force followed by peak displacement.  The transient occurring from peak force to peak 
80 
 
displacement suggests the presence of short impact response dominated by flexural and shear waves 
as observed in [31]. 
The original scope of this project involved developing a weather resistant covering for vehicles 
and small aircraft.  Weather resistant coverings should provide resistance against natural hazards 
including ultraviolet degradation, wind abrasion, moisture, and impact.  Resistance to impact is most 
critical for protection during hail storms and therefore we set out to develop an impact resistant 
covering against hail stones up to 2 inches in diameter.  After systematic evaluation of materials 
based on various mechanical characterization techniques, we have determined that the available 
materials are unsuitable for protecting against 2 inch hail stones.  However, we have concluded that 
the evaluated material configurations provide adequate protection against hailstones up to 
approximately 1.6 inches in diameter, which are more common than 2 inch diameters. 
Finally, the results of this work include developing a method for evaluating polymeric materials 
for weather resistance, designing and constructing a custom experimental test chamber for impact 
studies and future material impact experiments.  The significance of the work presented in this thesis 
supports the development of novel, weather resistant, and robust material coverings which are not 
currently commercially available.  
 
 
 
 
 
 
 
 
81 
 
 
 
6. RECOMMENDATIONS FOR FUTURE WORK 
 
Additional work is required to develop a material that can provide adequate impact resistance 
against larger than two inch diameter hailstones.  Additional layers utilizing high strength ballistic 
grade yarns such as Kevlar? or ballistic nylon should be investigated.   
Increasing the instrumentation capabilities of the impact simulation enclosure developed in this 
thesis would provide detailed information about material properties.  Specifically strain gages, C-
scan, and thermal imaging techniques would enable more detailed evaluation of material 
performance.  Application of appropriate micromechanics models and corresponding experiments 
should be investigated to determine appropriate constituent material models for developing finite 
element analyses.  A predictive finite element model will greatly expedite the design of new material 
configurations used in future impact studies. 
 
 
 
 
 
 
 
 
 
 
82 
 
 
 
REFERENCES 
 
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3. Manas, C. and R. Salil, Plastics Technology Handbook. 3rd ed, ed. M. Dekker. 1998, New York, 
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4. Halliwell, S.M., Weathering of Polymers, ed. R.R. Reports. 1995, Shawbury, UK. 
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83 
 
12. Burt, C.C., Extreme Weather: A Guide and Record Book. 2007, New York: W. W. Norton & 
Company. 
13. Schleusener, R.A. and P.C. Jennings, An Energy Method for Relative Estimates of Hail Intensity. 
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1080-1984. 
21. Schroeder, R.C. and W.H. McMaster, Shock-compression freezing and melting of water and ice. 
Journal of Applied Physics, 1973. 44(6): p. 2591-2594. 
22. Gokhale, N.R., Hailstorms and hailstone growth. 1975, Albany: State University of New York 
Press. 
23. Ross, D.v.d.S. and A.E. Carte, The Falling Behaviour of Oblate and Spiky Hailstones. Journal de 
Recherches Atmospheriques, 1973. 7: p. 39-52. 
84 
 
24. Lozowski, E.P. and G.S. Strong, Further reflections on the calibration of hailpads. Atmosphere 
Ocean, 1978. 16: p. 69-80. 
25. Beattie, A.G., Measurements of the kinematics of natural hailstones near ground. Quarterly Journal of 
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coverings and membranes. 2001, RCI Interface. p. 4-10. 
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Pretoria, South Africa. 
29. Bilham, E.G. and E.F. Relf, The dynamics of large hailstones. Quarterly Journal of the Royal 
Meteorological Society, 1937. 63: p. 149?162. 
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Applied Science and Manufacturing, 2000. 31(8): p. 879-887. 
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33. Fischer-Cripps, A.C., Introduction to Contact Mechanics. 2007, New York: Springer Science. 
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129-137. 
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85 
 
37. Asp, L.E. and R. Juntikka, High velocity impact on NCF reinforced composites. Composites Science 
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A: Applied Science and Manufacturing, 2001. 32(9): p. 1207-1215. 
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knitted composite. Composites Part B: Engineering, 2009. 40(6): p. 572-583. 
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86 
 
 
 
APPENDICES 
 
Appendix A. Specifications of materials acquired to Innovative Insulation Inc. [42] 
TempShield? Single Bubble Foil/Foil  
CONTACT TEMPERATURE 
RANGE  -60 ?F to 180 ?F  (-51 ?C to 82 ?C) 
THICKNESS  5/32" nominal 
WATER VAPOR 
TRANSMISSION  0.02 perms [ASTM E-96 Method A] 
PUNCTURE RESISTANCE  60 lbs/in  [ASTM Test Method D-781] 
PLIABILITY  No Cracking 
LINEAR SHRINKAGE  None 
MOLD AND MILDEW  No Growth 
FLAME SPREAD  0  [ASTM E84-08] 
SMOKE DEVELOPMENT  25 [ASTM E84-08] 
FIRE RATING  Class A/Class 1 
REFLECTIVITY  95% 
EMITTANCE  0.04 on metalized film side 
 
TempShield? Single Bubble White/Foil  
CONTACT TEMPERATURE 
RANGE  -60 ?F to 180 ?F  (-51 ?C to 82 ?C) 
THICKNESS  5/32" nominal 
WATER VAPOR 
TRANSMISSION  0.02 perms [ASTM E-96 Method A] 
PUNCTURE RESISTANCE  60 lbs/in  [ASTM Test Method D-781] 
PLIABILITY  No Cracking 
LINEAR SHRINKAGE  None 
MOLD AND MILDEW  No Growth 
FLAME SPREAD  0  [ASTM E84-08] 
SMOKE DEVELOPMENT  20 [ASTM E84-08] 
FIRE RATING  Class A/Class 1 
REFLECTIVITY  95% 
EMITTANCE  0.04 on metalized film side 
87 
 
Temptrol? Heat Reflecting Fabric  
NOMINAL THICKNESS  10.9 mils 
TENSILE STRENGTH  47.0 lb/in width [ASTM Test Method D751] 
TEAR STRENGTH  6.0 lb/in width [ASTM Test Method D751] 
PUNCTURE RESISTANCE  17 lbs. [ASTM Test Method 4833] 
MULLEN BURST STRENGTH  55.0 psi [ASTM Test Method D751] 
LOW TEMPERATURE BEND  131? F PASS [ASTM D2136] 
WATER VAPOR 
PERMEABILITY  87.5g/m2/24hr [ASTM E96] 
FLAMMABILITY  Class B [ASTM E84-94] 
THERMAL PROPERTIES  
Emissivity 0.05 (Reflects 95% of Infrared Energy) [ASTM 
E408] 
 
 
Super R Plus?  
TENSILE/TEAR 
STRENGTH  
Length 13.23 pounds force [ASTM D2261] 
Width 13.98 pounds force 
PLIABILITY  70?F?5?F & 50?5% Relative Humidity ? No Cracking or Delamination  [ASTM C1313-05] 
ADHESIVE 
PERFORMANCE  
180?F?5?F & 50% Relative Humidity ? No 
Bleeding or Delamination [ASTM C1313-05] 
FLAME SPREAD & 
SMOKE  
Class A/ Class 1 [ASTM Method E84-10] 
0 Flame Spread, 5 Smoke Development  
CORROSIVITY  100% humidity at 71?2?C for 7 days - PASS [ASTM D3310-00] 
RESISTANCE TO 
FUNGI  PASS ? No Growth [ASTM C1338-08] 
PERMEABILITY  6.3 Perms [ASTM E96-05] 
THERMAL 
PROPERTIES  
EMISSIVITY 0.05 [ASTM C1371-04a] 
REFLECTIVITY 95%  
 
 
 
 
 
 
88 
 
Appendix B. Complete results of abrasion test 
 
Table 22 Results after abrasion of the heat reflecting fabric (grams) 
 
 
 
Figure 61 Average of weight loss vs. number cycles of the heat reflecting fabric 
 
 
 
 
 
C y c l e s
S p e c i m e n W 0
W e i g h t  
l o s s  0
W 10
W e i g h t  
l o s s  10
W 25
W e i g h t  
l o s s  25
W 50
W e i g h t  
l o s s  50
W 1 0 0
W e i g h t  
l o s s  1 0 0
1 7 8 3 . 1 0 0 . 0 0 7 8 2 . 9 0 0 . 2 0 7 8 2 . 7 0 0 . 4 0 7 8 2 . 5 0 0 . 6 0 7 8 2 . 0 0 1 . 1 0
2 7 4 4 . 8 0 0 . 0 0 7 4 4 . 7 0 0 . 1 0 7 4 4 . 5 0 0 . 3 0 7 4 4 . 3 0 0 . 5 0 7 4 4 . 0 0 0 . 8 0
3 7 2 1 . 0 0 0 . 0 0 7 2 0 . 8 0 0 . 2 0 7 2 0 . 7 0 0 . 3 0 7 2 0 . 5 0 0 . 5 0 7 2 0 . 1 0 0 . 9 0
4 7 0 8 . 2 0 0 . 0 0 7 0 8 . 1 0 0 . 1 0 7 0 7 . 8 0 0 . 4 0 7 0 7 . 6 0 0 . 6 0 7 0 7 . 3 0 0 . 9 0
5 8 1 7 . 0 0 0 . 0 0 8 1 6 . 8 0 0 . 2 0 8 1 6 . 7 0 0 . 3 0 8 1 6 . 5 0 0 . 5 0 8 1 6 . 1 0 0 . 9 0
A v e r a g e 7 5 4 . 8 2 0 . 0 0 7 5 4 . 6 6 0 . 1 6 7 5 4 . 4 8 0 . 3 4 7 5 4 . 2 8 0 . 5 4 7 5 3 . 9 0 0 . 9 2
S t a n d a r d  d e v i a t i o n 0 . 0 5 0 . 0 5 0 . 0 5 0 . 1 1
C o n f i d e n c e  i n t e r v a l 0 . 0 4 0 . 0 4 0 . 0 4 0 . 0 8
0 10 25 50 1000 10 20 30 40 50 60 70 80 90 100
0 .0 0
0 .2 5
0 .5 0
0 .7 5
1 .0 0
W
e
ig
h
t 
lo
ss 
(g
)
C y cl e s
 A v e r a g e  5  sp e cim e n s h e a t  r e f le ct in g  f a b r ic
 Y  =  0 . 0 0 8 8 7   X  +  0 . 0 6 3 8 7  
         R  =  0 .9 9 1 0 4
 9 0 % Co n f id e n ce  li m its
89 
 
Table 23 Results after abrasion of the single bubble/white foil (grams) 
 
 
 
Figure 62 Average of weight loss vs. number cycles of the single bubble/white foil 
 
 
 
 
 
 
C y c l e s
S p e c i m e n W 0
W e i g h t  
l o s s  0
W 10
W e i g h t  
l o s s  10
W 25
W e i g h t  
l o s s  25
W 50
W e i g h t  
l o s s  50
W 1 0 0
W e i g h t  
l o s s  1 0 0
1 1 2 5 6 . 8 0 0 . 0 0 1 2 5 6 . 2 0 0 . 6 0 1 2 5 5 . 8 0 1 . 0 0 1 2 5 5 . 5 0 1 . 3 0 1 2 5 4 . 3 0 2 . 5 0
2 1 2 5 9 . 6 0 0 . 0 0 1 2 5 8 . 9 0 0 . 7 0 1 2 5 8 . 5 0 1 . 1 0 1 2 5 7 . 9 0 1 . 7 0 1 2 5 6 . 5 0 3 . 1 0
3 1 2 7 3 . 1 0 0 . 0 0 1 2 7 2 . 8 0 0 . 3 0 1 2 7 2 . 5 0 0 . 6 0 1 2 7 1 . 8 0 1 . 3 0 1 2 7 0 . 7 0 2 . 4 0
4 1 2 3 2 . 5 0 0 . 0 0 1 2 3 2 . 0 0 0 . 5 0 1 2 3 1 . 6 0 0 . 9 0 1 2 3 1 . 1 0 1 . 4 0 1 2 2 9 . 9 0 2 . 6 0
5 1 3 1 0 . 7 0 0 . 0 0 1 3 1 0 . 2 0 0 . 5 0 1 3 0 9 . 7 0 1 . 0 0 1 3 0 9 . 2 0 1 . 5 0 1 3 0 8 . 3 0 2 . 4 0
A v e r a g e 1 2 6 6 . 5 4 0 . 0 0 1 2 6 6 . 0 2 0 . 5 2 1 2 6 5 . 6 2 0 . 9 2 1 2 6 5 . 1 0 1 . 4 4 1 2 6 3 . 9 4 2 . 6 0
S t a n d a r d  d e v i a t i o n 0 . 1 5 0 . 1 9 0 . 1 7 0 . 2 9
C o n f i d e n c e  i n t e r v a l 0 . 1 1 0 . 1 4 0 . 1 2 0 . 2 1
0 10 25 50 100
0 10 20 30 40 50 60 70 80 90 100
0 .0
0 .5
1 .0
1 .5
2 .0
2 .5
3 .0
W
e
ig
h
t 
lo
ss 
(g
)
C y cl e s
 A v e r a g e  5  sp e cim e n s sin g le  b u b b le / w h ite  f o il  
 Y  =  0 . 0 2 4 6 8  X  +  0 . 1 8 2 9 5  
         R  =  0 .9 9 2 4 7
 9 0 % Co n f id e n ce  li m its
90 
 
Table 24 Results after abrasion of the two-sided film with polyester scrim reinforcement 
(grams) 
 
 
 
 Figure 63 Average of weight loss vs. number cycles of the two-sided film with polyester scrim 
reinforcement  
 
 
 
 
 
C y c l e s
S p e c i m e n W 0
W e i g h t  
l o s s  0
W 10
W e i g h t  
l o s s  10
W 25
W e i g h t  
l o s s  25
W 50
W e i g h t  
l o s s  50
W 1 0 0
W e i g h t  
l o s s  1 0 0
1 1 0 7 0 . 2 0 0 . 0 0 1 0 6 9 . 6 0 0 . 6 0 1 0 6 8 . 9 0 1 . 3 0 1 0 6 8 . 2 0 2 . 0 0 1 0 6 7 . 1 0 3 . 1 0
2 1 0 6 4 . 3 0 0 . 0 0 1 0 6 3 . 7 0 0 . 6 0 1 0 6 3 . 1 0 1 . 2 0 1 0 6 2 . 3 0 2 . 0 0 1 0 6 0 . 9 0 3 . 4 0
3 1 0 6 6 . 2 0 0 . 0 0 1 0 6 5 . 6 0 0 . 6 0 1 0 6 5 . 1 0 1 . 1 0 1 0 6 4 . 5 0 1 . 7 0 1 0 6 3 . 5 0 2 . 7 0
4 1 0 6 0 . 4 0 0 . 0 0 1 0 5 9 . 9 0 0 . 5 0 1 0 5 9 . 6 0 0 . 8 0 1 0 5 8 . 9 0 1 . 5 0 1 0 5 8 . 0 0 2 . 4 0
5 1 0 7 7 . 4 0 0 . 0 0 1 0 7 7 . 0 0 0 . 4 0 1 0 7 6 . 5 0 0 . 9 0 1 0 7 5 . 7 0 1 . 7 0 1 0 7 4 . 5 0 2 . 9 0
A v e r a g e 1 0 6 7 . 7 0 0 . 0 0 1 0 6 7 . 1 6 0 . 5 4 1 0 6 6 . 6 4 1 . 0 6 1 0 6 5 . 9 2 1 . 7 8 1 0 6 4 . 8 0 2 . 9 0
S t a n d a r d  d e v i a t i o n 0 . 0 9 0 . 2 1 0 . 2 2 0 . 3 8
C o n f i d e n c e  i n t e r v a l 0 . 0 7 0 . 1 5 0 . 1 6 0 . 2 8
0 10 25 50 100
0 10 20 30 40 50 60 70 80 90 100
0 .0
0 .5
1 .0
1 .5
2 .0
2 .5
3 .0
W
e
ig
h
t 
lo
ss 
(g
)
C y cl e s
 A v e r a g e  5  sp e cim e n s t w o - sid e d  f il m  p o ly e st e r  scr im  r e in f o r ce m e n t
 Y  =  0 . 0 2 7 9 8  X  +  0 . 2 2 0 5 8   
         R  =  0 .9 8 9 2 1
 9 0 % Co n f id e n ce  li m its
91 
 
Table 25 Results after abrasion of the single bubble/double foil (circular embossing) (grams) 
 
 
 
 Figure 64 Average of weight loss vs. number cycles of the single bubble/double foil (circular 
embossing) 
 
 
 
 
 
 
C y c l e s
S p e c i m e n W 0
W e i g h t  
l o s s  0
W 10
W e i g h t  
l o s s  10
W 25
W e i g h t  
l o s s  25
W 50
W e i g h t  
l o s s  50
W 1 0 0
W e i g h t  
l o s s  1 0 0
1 1 4 4 0 . 3 0 0 . 0 0 1 4 3 9 . 6 0 0 . 7 0 1 4 3 9 . 0 0 1 . 3 0 1 4 3 7 . 8 0 2 . 5 0 1 4 3 5 . 6 0 4 . 7 0
2 1 4 5 2 . 9 0 0 . 0 0 1 4 5 2 . 2 0 0 . 7 0 1 4 5 1 . 7 0 1 . 2 0 1 4 5 0 . 8 0 2 . 1 0 1 4 4 9 . 0 0 3 . 9 0
3 1 4 5 4 . 9 0 0 . 0 0 1 4 5 4 . 2 0 0 . 7 0 1 4 5 3 . 8 0 1 . 1 0 1 4 5 2 . 8 0 2 . 1 0 1 4 5 1 . 0 0 3 . 9 0
4 1 4 4 7 . 3 0 0 . 0 0 1 4 4 6 . 7 0 0 . 6 0 1 4 4 6 . 2 0 1 . 1 0 1 4 4 5 . 3 0 2 . 0 0 1 4 4 3 . 5 0 3 . 8 0
5 1 4 3 5 . 9 0 0 . 0 0 1 4 3 5 . 5 0 0 . 4 0 1 4 3 5 . 1 0 0 . 8 0 1 4 3 4 . 1 0 1 . 8 0 1 4 3 2 . 3 0 3 . 6 0
A v e r a g e 1 4 4 6 . 2 6 0 . 0 0 1 4 4 5 . 6 4 0 . 6 2 1 4 4 5 . 1 6 1 . 1 0 1 4 4 4 . 1 6 2 . 1 0 1 4 4 2 . 2 8 3 . 9 8
S t a n d a r d  d e v i a t i o n 0 . 1 3 0 . 1 9 0 . 2 5 0 . 4 2
C o n f i d e n c e  i n t e r v a l 0 . 1 0 0 . 1 4 0 . 1 9 0 . 3 1
0 10 25 50 100
0 10 20 30 40 50 60 70 80 90 100
0 .0
0 .5
1 .0
1 .5
2 .0
2 .5
3 .0
3 .5
4 .0
W
e
ig
h
t 
lo
ss 
(g
)
C y cl e s
 A v e r a g e  5  sp e cim e n s sin g le  b u b b le / d o u b le  f o il  ( cir cle  sid e )
 Y  =  0 . 0 3 8 8 9  X  +  0 . 1 2 1 1 8   
         R  =  0 .9 9 8 5 1
 9 0 % Co n f id e n ce  li m its
92 
 
Table 26 Results after abrasion of the single bubble/double foil (triaxial embossing) (grams) 
 
 
 
Figure 65 Average of weight loss vs. number cycles of the single bubble/double foil (triaxial 
embossing) 
 
 
 
 
 
 
C y c l e s
S p e c i m e n W 0
W e i g h t  
l o s s  0
W 10
W e i g h t  
l o s s  10
W 25
W e i g h t  
l o s s  25
W 50
W e i g h t  
l o s s  50
W 1 0 0
W e i g h t  
l o s s  1 0 0
1 1 4 2 8 . 2 0 0 . 0 0 1 4 2 7 . 7 0 0 . 5 0 1 4 2 7 . 2 0 1 . 0 0 1 4 2 6 . 4 0 1 . 8 0 1 4 2 5 . 4 0 2 . 8 0
2 1 4 6 9 . 6 0 0 . 0 0 1 4 6 9 . 2 0 0 . 4 0 1 4 6 8 . 6 0 1 . 0 0 1 4 6 7 . 8 0 1 . 8 0 1 4 6 7 . 1 0 2 . 5 0
3 1 4 3 5 . 7 0 0 . 0 0 1 4 3 5 . 3 0 0 . 4 0 1 4 3 4 . 4 0 1 . 3 0 1 4 3 4 . 0 0 1 . 7 0 1 4 3 3 . 2 0 2 . 5 0
4 1 4 6 0 . 7 0 0 . 0 0 1 4 6 0 . 3 0 0 . 4 0 1 4 5 9 . 7 0 1 . 0 0 1 4 5 9 . 0 0 1 . 7 0 1 4 5 8 . 0 0 2 . 7 0
5 1 4 6 3 . 4 0 0 . 0 0 1 4 6 3 . 0 0 0 . 4 0 1 4 6 2 . 4 0 1 . 0 0 1 4 6 1 . 6 0 1 . 8 0 1 4 6 0 . 6 0 2 . 8 0
A v e r a g e 1 4 5 1 . 5 2 0 . 0 0 1 4 5 1 . 1 0 0 . 4 2 1 4 5 0 . 4 6 1 . 0 6 1 4 4 9 . 7 6 1 . 7 6 1 4 4 8 . 8 6 2 . 6 6
S t a n d a r d  d e v i a t i o n 0 . 0 4 0 . 1 3 0 . 0 5 0 . 1 5
C o n f i d e n c e  i n t e r v a l 0 . 0 3 0 . 1 0 0 . 0 4 0 . 1 1
0 10 25 50 1000 10 20 30 40 50 60 70 80 90 100
0 .0
0 .5
1 .0
1 .5
2 .0
2 .5
3 .0
W
e
ig
h
t 
lo
ss 
(g
)
C y cl e s
 A v e r a g e  5  sp e cim e n s sin g le  b u b b le / d o u b le  f o il  ( st r ip e  sid e )
 Y  =  0 . 0 2 6 0 8  * X  +  0 . 2 1 4 9 8
         R  =  0 .9 8 0 8 4
 9 0 % Co n f id e n ce  li m its
93 
 
Appendix C. Complete results of impact resistance test 
 
Table 27 Results after impact resistance test of the two-sided film with polyester scrim 
reinforcement 
   
 
 
Figure 66 Load vs. Time of two-sided film with polyester scrim reinforcement 
 
 
 
 
S p e c i m e n
M a x i m u m  
L o a d                
( N )
T i m e  t o  
m a x  l o a d -1               
( m s )
Im p a c t  
v e l o c i t y -1                   
( m / s )
T o t a l  
e n e r g y -1        
( J )
E n e r g y  t o  
m a x  l o a d -1 
( J )
T o t a l  t i m e -1              
( m s )
Im p a c t  
e n e r g y -1       
( J )
1 2 4 0 . 9 0 8 . 6 7 1 . 5 1 1 . 1 6 1 . 1 2 8 . 9 5 3 . 1 2
2 2 7 2 . 7 0 9 . 4 0 1 . 5 2 1 . 3 6 1 . 3 4 9 . 5 1 3 . 1 4
3 3 0 4 . 3 0 1 0 . 1 3 1 . 5 2 1 . 6 2 1 . 5 9 1 0 . 2 9 3 . 1 3
4 2 5 6 . 9 0 9 . 2 1 1 . 5 1 1 . 2 8 1 . 2 4 9 . 3 9 3 . 1 1
5 2 3 6 . 4 0 8 . 6 3 1 . 5 1 1 . 3 1 1 . 1 0 9 . 5 0 3 . 1 1
A v e r a g e 2 6 2 . 2 4 9 . 2 1 1 . 5 1 1 . 3 4 1 . 2 8 9 . 5 3 3 . 1 2
S t a n d a r d  d e v i a t i o n 2 7 . 5 2 0 . 6 2 0 . 0 0 0 . 1 7 0 . 2 0 0 . 4 8 0 . 0 1
C o n f i d e n c e  i n t e r v a l 2 0 . 2 5 0 . 4 5 0 . 0 0 0 . 1 3 0 . 1 5 0 . 3 5 0 . 0 1
94 
 
Table 28 Results after impact resistance test of the single bubble/double foil 
  
 
 
Figure 67 Load vs. Time of single bubble/white foil 
 
 
 
 
 
 
 
 
S p e c i m e n
M a x i m u m  
L o a d                
( N )
T i m e  t o  
m a x  l o a d -1               
( m s )
Im p a c t  
v e l o c i t y -1                   
( m / s )
T o t a l  
e n e r g y -1        
( J )
E n e r g y  t o  
m a x  l o a d -1 
( J )
T o t a l  t i m e -1              
( m s )
Im p a c t  
e n e r g y -1       
( J )
1 1 1 2 . 9 0 9 . 5 5 1 . 5 1 0 . 8 1 0 . 7 6 1 1 . 1 0 3 . 1 2
2 1 2 1 . 0 0 1 0 . 3 8 1 . 5 0 0 . 9 3 0 . 8 7 1 2 . 5 0 3 . 0 8
3 1 1 6 . 7 0 9 . 9 1 1 . 5 1 0 . 8 5 0 . 8 0 1 1 . 4 3 3 . 1 2
4 1 2 3 . 6 0 9 . 8 8 1 . 5 2 0 . 9 3 0 . 8 4 1 2 . 7 5 3 . 1 4
5 1 3 0 . 2 0 9 . 8 0 1 . 5 2 0 . 9 5 0 . 8 6 1 2 . 4 0 3 . 1 3
A v e r a g e 1 2 0 . 8 8 9 . 9 0 1 . 5 1 0 . 8 9 0 . 8 3 1 2 . 0 4 3 . 1 2
S t a n d a r d  d e v i a t i o n 6 . 6 2 0 . 3 0 0 . 0 1 0 . 0 6 0 . 0 4 0 . 7 2 0 . 0 2
C o n f i d e n c e  i n t e r v a l 4 . 8 7 0 . 2 2 0 . 0 0 0 . 0 4 0 . 0 3 0 . 5 3 0 . 0 2
95 
 
Table 29 Results after impact resistance test of heat reflecting fabric 
  
 
 
Figure 68 Load vs. Time of heat reflecting fabric 
 
 
 
 
 
 
 
 
S p e c i m e n
M a x i m u m  
L o a d                
( N )
T i m e  t o  
m a x  l o a d -1               
( m s )
Im p a c t  
v e l o c i t y -1                   
( m / s )
T o t a l  
e n e r g y -1        
( J )
E n e r g y  t o  
m a x  l o a d -1 
( J )
T o t a l  t i m e -1              
( m s )
Im p a c t  
e n e r g y -1       
( J )
1 9 1 . 1 0 9 . 2 4 1 . 5 3 0 . 6 1 0 . 5 7 9 . 7 6 3 . 1 7
2 8 2 . 3 0 8 . 7 8 1 . 5 3 0 . 5 4 0 . 5 0 9 . 1 9 3 . 1 8
3 8 1 . 1 0 8 . 5 1 1 . 5 3 0 . 5 3 0 . 4 8 9 . 2 1 3 . 1 8
4 9 2 . 0 0 8 . 9 1 1 . 5 2 0 . 6 2 0 . 5 5 9 . 7 0 3 . 1 5
5 8 7 . 6 0 8 . 4 1 1 . 5 2 0 . 5 3 0 . 4 8 8 . 9 8 3 . 1 5
A v e r a g e 8 6 . 8 2 8 . 7 7 1 . 5 2 0 . 5 6 0 . 5 2 9 . 3 7 3 . 1 7
S t a n d a r d  d e v i a t i o n 4 . 9 7 0 . 3 3 0 . 0 0 0 . 0 4 0 . 0 4 0 . 3 4 0 . 0 2
C o n f i d e n c e  i n t e r v a l 3 . 6 6 0 . 2 4 0 . 0 0 0 . 0 3 0 . 0 3 0 . 2 5 0 . 0 1
96 
 
Table 30 Results after impact resistance test of single bubble/double foil 
  
 
Figure 69 Load vs. Time of single bubble/double foil 
 
 
 
 
 
 
 
 
S p e c i m e n
M a x i m u m  
L o a d                
( N )
T i m e  t o  
m a x  l o a d -1               
( m s )
Im p a c t  
v e l o c i t y -1                   
( m / s )
T o t a l  
e n e r g y -1        
( J )
E n e r g y  t o  
m a x  l o a d -1 
( J )
T o t a l  t i m e -1              
( m s )
Im p a c t  
e n e r g y -1       
( J )
1 3 2 . 7 0 6 . 3 9 1 . 5 1 0 . 3 2 0 . 1 8 2 0 . 6 7 3 . 1 2
2 3 6 . 6 0 6 . 2 0 1 . 5 1 0 . 3 3 0 . 1 9 2 0 . 4 2 3 . 0 9
3 3 4 . 0 0 6 . 2 7 1 . 5 2 0 . 2 9 0 . 1 8 2 0 . 6 1 3 . 1 4
4 3 1 . 8 0 6 . 0 9 1 . 5 1 0 . 3 1 0 . 1 7 2 0 . 6 4 3 . 1 2
5 3 1 . 8 0 6 . 2 8 1 . 5 2 0 . 2 8 0 . 1 8 2 0 . 5 4 3 . 1 3
A v e r a g e 3 3 . 3 8 6 . 2 5 1 . 5 1 0 . 3 1 0 . 1 8 2 0 . 5 8 3 . 1 2
S t a n d a r d  d e v i a t i o n 2 . 0 1 0 . 1 1 0 . 0 0 0 . 0 2 0 . 0 1 0 . 1 0 0 . 0 2
C o n f i d e n c e  i n t e r v a l 1 . 4 8 0 . 0 8 0 . 0 0 0 . 0 1 0 . 0 0 0 . 0 7 0 . 0 1
97 
 
Table 31 Results after impact resistance test of bubble wrap 
 
 
 
Figure 70 Load vs. Time of bubble wrap 
 
 
 
 
 
 
 
S p e c i m e n
M a x i m u m  
L o a d                
( N )
T i m e  t o  
m a x  l o a d -1               
( m s )
Im p a c t  
v e l o c i t y -1                   
( m / s )
T o t a l  
e n e r g y -1        
( J )
E n e r g y  t o  
m a x  l o a d -1 
( J )
T o t a l  t i m e -1              
( m s )
Im p a c t  
e n e r g y -1       
( J )
1 3 2 . 2 0 8 . 1 6 1 . 5 3 0 . 2 8 0 . 2 1 1 6 . 9 3 3 . 2 0
2 3 8 . 3 0 9 . 9 5 1 . 5 3 0 . 3 2 0 . 3 2 1 7 . 9 0 3 . 2 1
3 3 3 . 1 0 9 . 8 4 1 . 5 4 0 . 3 0 0 . 2 9 1 6 . 8 6 3 . 2 2
4 3 3 . 1 0 9 . 8 8 1 . 5 3 0 . 2 9 0 . 2 9 1 6 . 9 8 3 . 2 0
5 3 1 . 3 0 8 . 9 2 1 . 5 3 0 . 3 0 0 . 2 5 1 7 . 8 7 3 . 2 1
A v e r a g e 3 3 . 6 0 9 . 3 5 1 . 5 3 0 . 3 0 0 . 2 7 1 7 . 3 1 3 . 2 1
S t a n d a r d  d e v i a t i o n 2 . 7 3 0 . 7 9 0 . 0 0 0 . 0 2 0 . 0 4 0 . 5 3 0 . 0 1
C o n f i d e n c e  i n t e r v a l 2 . 0 1 0 . 5 8 0 . 0 0 0 . 0 1 0 . 0 3 0 . 3 9 0 . 0 1
98 
 
Table 32 Results after impact resistance test of polyethylene film 
 
 
 
Figure 71 Load vs. Time of polyethylene film 
 
 
 
 
 
 
 
S p e c i m e n
M a x i m u m  
L o a d                
( N )
T i m e  t o  
m a x  l o a d -1               
( m s )
Im p a c t  
v e l o c i t y -1                   
( m / s )
T o t a l  
e n e r g y -1        
( J )
E n e r g y  t o  
m a x  l o a d -1 
( J )
T o t a l  t i m e -1              
( m s )
Im p a c t  
e n e r g y -1       
( J )
1 7 5 . 0 0 1 0 . 1 0 1 . 5 2 0 . 8 3 0 . 6 4 1 2 . 5 2 3 . 1 6
2 6 7 . 6 0 9 . 1 1 1 . 5 3 0 . 8 1 0 . 5 2 1 3 . 2 8 3 . 1 9
3 7 9 . 3 0 1 0 . 7 3 1 . 5 2 0 . 9 4 0 . 7 6 1 2 . 8 4 3 . 1 4
4 8 0 . 6 0 8 . 6 3 1 . 5 3 1 . 0 5 0 . 5 8 1 6 . 1 3 3 . 1 8
5 7 3 . 6 0 9 . 7 7 1 . 5 3 0 . 8 8 0 . 6 3 1 3 . 4 5 3 . 1 8
A v e r a g e 7 5 . 2 2 9 . 6 7 1 . 5 3 0 . 9 0 0 . 6 3 1 3 . 6 4 3 . 1 7
S t a n d a r d  d e v i a t i o n 5 . 1 6 0 . 8 2 0 . 0 1 0 . 1 0 0 . 0 9 1 . 4 4 0 . 0 2
C o n f i d e n c e  i n t e r v a l 3 . 7 9 0 . 6 1 0 . 0 0 0 . 0 7 0 . 0 6 1 . 0 6 0 . 0 2
99 
 
Appendix D. Complete results of tear resistance test 
Table 33 Results after tear resistance test 
 
 
 
 
 
 
 
 
 
 
 
S p e c i m e n
A v e r a g e  L o a d  
( In t e g r a l )         
( N )
F i r s t  P e a k 
( L o a d  10 %  
C h a n g e )  ( N )
M a x i m u m  
L o a d                 
( N )
E x t e n s i o n  a t  
M a x i m u m  
L o a d           
( m m )
A v e r a g e  L o a d  
( In t e g r a l )         
( N )
F i r s t  P e a k 
( L o a d  10 %  
C h a n g e )  ( N )
M a x i m u m  
L o a d                 
( N )
E x t e n s i o n  a t  
M a x i m u m  
L o a d           
( m m )
1 1 2 . 6 8 1 6 . 9 9 1 6 . 9 9 6 9 . 5 8 1 1 . 9 9 1 5 . 6 5 1 6 . 5 1 6 4 . 1 7
2 1 1 . 3 1 1 8 . 6 7 1 8 . 6 7 7 9 . 1 7 1 4 . 3 2 2 0 . 4 2 2 0 . 4 2 5 9 . 5 8
3 1 4 . 5 3 1 9 . 5 0 1 9 . 5 0 7 5 . 4 2 1 1 . 6 6 1 8 . 1 8 1 8 . 1 8 5 9 . 5 8
4 1 3 . 4 0 1 9 . 3 7 1 9 . 3 7 9 0 . 8 3 1 2 . 5 0 1 1 . 8 3 1 8 . 7 9 6 1 . 2 5
5 1 1 . 1 6 1 6 . 1 4 1 6 . 1 4 7 0 . 8 3 1 2 . 6 2 1 8 . 1 9 1 8 . 1 9 5 6 . 6 7
A v e r a g e 1 2 . 6 2 1 8 . 1 3 1 8 . 1 3 7 7 . 1 7 1 2 . 6 2 1 6 . 8 5 1 8 . 4 2 6 0 . 2 5
S t a n d a r d  d e v i a t i o n 1 . 4 2 1 . 5 0 1 . 5 0 8 . 5 4 1 . 0 3 3 . 2 8 1 . 4 1 2 . 7 4
C o n f i d e n c e  i n t e r v a l 1 . 0 5 1 . 1 0 1 . 1 0 6 . 2 8 0 . 7 6 2 . 4 1 1 . 0 3 2 . 0 2
S i n g l e  B u b b l e / D o u b l e  F o i l S i n g l e  B u b b l e / W h i t e  F o i l
S p e c i m e n
A v e r a g e  L o a d  
( I n t e g r a l )         
( N )
F i r s t  P e a k 
( L o a d  1 0  %  
C h a n g e )  ( N )
M a x i m u m  
L o a d                 
( N )
E x t e n s i o n  a t  
M a x i m u m  
L o a d           
( m m )
A v e r a g e  L o a d  
( I n t e g r a l )         
( N )
F i r s t  P e a k 
( L o a d  1 0  %  
C h a n g e )  ( N )
M a x i m u m  
L o a d                 
( N )
E x t e n s i o n  a t  
M a x i m u m  
L o a d           
( m m )
1 7 . 0 4 1 3 . 0 7 1 3 . 0 7 3 5 . 0 0 1 6 . 7 2 2 4 . 6 2 2 4 . 6 2 2 9 . 5 8
2 1 2 . 8 4 2 1 . 8 6 2 1 . 8 6 4 0 . 8 3 1 5 . 4 4 2 4 . 2 9 2 4 . 2 9 2 2 . 9 2
3 1 2 . 5 2 1 6 . 7 3 1 7 . 3 9 3 4 . 1 7 1 8 . 1 3 2 6 . 4 0 2 6 . 4 0 2 6 . 2 5
4 1 8 . 4 3 2 4 . 7 2 2 4 . 7 2 4 9 . 1 7 2 1 . 4 1 1 8 . 7 9 3 3 . 5 0 2 9 . 5 8
5 1 1 . 0 2 1 8 . 4 1 1 8 . 4 1 3 9 . 1 7 2 0 . 2 5 2 3 . 7 0 2 8 . 3 2 2 7 . 9 2
A v e r a g e 1 2 . 3 7 1 8 . 9 6 1 9 . 0 9 3 9 . 6 7 1 8 . 3 9 2 3 . 5 6 2 7 . 4 2 2 7 . 2 5
S t a n d a r d  d e v i a t i o n 4 . 1 0 4 . 5 2 4 . 4 4 6 . 0 0 2 . 4 6 2 . 8 5 3 . 7 6 2 . 7 9
C o n f i d e n c e  i n t e r v a l 3 . 0 2 3 . 3 2 3 . 2 7 4 . 4 1 1 . 8 1 2 . 1 0 2 . 7 6 2 . 0 5
He a t  R e f l e c t i n g  F a b r i c T w o -s i d e d  F i l m  P o l y e s t e r  w i t h  S c r i m  R e i n f o r c e m e n t
100 
 
       
a) Single Bubble/Double Foil                            (b) Single Bubble/White Foil 
        
            (c) Heat Reflecting Fabric                                (d) Two-sided Film with Polyester Scrim  
Figure 72 Load vs. Extension of outside layers 
 
 
 
 
 
 
 
 
0 20 40 60 80 100 120 140
0
2
4
6
8
10
12
14
16
18
20
22
L
o
a
d
 (N
)
Ex t e n si o n  (m m )
 1
 2
 3
 4
 5
0 20 40 60 80 100 120 140
0
2
4
6
8
10
12
14
16
18
20
22
L
o
a
d
 (N
)
Ex t e n si o n  (m m )
 1
 2
 3
 4
 5
0 10 20 30 40 50 60 70 80 90 100 110
0
2
4
6
8
10
12
14
16
18
20
22
24
26
L
o
a
d
 (N
)
Ex t e n si o n  (m m )
 1
 2
 3
 4
 5
0 10 20 30 40 50 60 70 80
0
5
10
15
20
25
30
35
L
o
a
d
 (N
)
Ex t e n si o n  (m m )
 1
 2
 3
 4
 5
101 
 
Appendix E. Complete results of bursting strength test 
Table 34 Results after bursting strength test of outside layers 
 
           
(a) Single Bubble/Double Foil                            (b) Single Bubble/White Foil  
          
            (c) Heat Reflecting Fabric                                (d) Two-sided Film with Polyester Scrim  
Figure 73 Load vs. Extension of outside layers 
S p e c i m e n
M a x i m u m  
L o a d             
( N )
E x t e n s i o n  a t  
M a x i m u m  
L o a d          
( m m )
M a x i m u m  
L o a d             
( N )
E x t e n s i o n  a t  
M a x i m u m  
L o a d          
( m m )
M a x i m u m  
L o a d             
( N )
E x t e n s i o n  a t  
M a x i m u m  
L o a d          
( m m )
M a x i m u m  
L o a d             
( N )
E x t e n s i o n  a t  
M a x i m u m  
L o a d          
( m m )
1 1 3 4 . 5 0 2 9 . 9 7 2 1 6 . 8 3 1 9 . 8 1 2 8 0 . 5 1 2 0 . 4 2 5 9 7 . 9 9 1 8 . 2 1
2 1 3 3 . 7 2 3 2 . 5 1 2 4 3 . 9 9 2 2 . 8 6 3 1 6 . 5 8 2 2 . 0 0 5 9 6 . 1 1 1 5 . 9 9
3 1 3 4 . 8 1 3 1 . 5 0 2 7 3 . 0 2 2 5 . 4 0 2 7 2 . 3 9 2 1 . 0 9 5 8 4 . 7 1 1 8 . 3 5
4 1 3 2 . 3 3 2 8 . 9 6 2 2 9 . 2 3 1 9 . 8 1 2 7 8 . 9 7 2 2 . 6 9 5 7 7 . 8 1 1 9 . 3 1
5 1 3 6 . 1 7 2 9 . 9 7 2 1 1 . 2 2 1 9 . 3 0 2 9 1 . 9 3 2 3 . 5 2 5 9 9 . 3 4 2 0 . 1 5
A v e r a g e 1 3 4 . 3 1 3 0 . 5 8 2 3 4 . 8 6 2 1 . 4 4 2 8 8 . 0 8 2 1 . 9 4 5 9 1 . 1 9 1 8 . 4 0
S t a n d a r d  d e v i a t i o n 1 . 4 2 1 . 4 1 2 4 . 7 7 2 . 6 3 1 7 . 4 2 1 . 2 3 9 . 4 6 1 . 5 6
C o n f i d e n c e  i n t e r v a l 1 . 0 4 1 . 0 4 1 8 . 2 2 1 . 9 3 1 2 . 8 1 0 . 9 1 6 . 9 6 1 . 1 5
S i n g l e  B u b b l e / D o u b l e  F o i l S i n g l e  B u b b l e / W h i t e  F o i l He a t  R e f l e c t i n g  F a b r i c
T w o -s i d e d  F i l m  w i t h  
P o l y e s t e r  S c r i m  
R e i n f o r c e m e n t
0 10 20 30 40
0
20
40
60
80
100
120
140
L
o
a
d
 (N
)
Ex t e n si o n  (m m )
 1
 2
 3
 4
 5
0 10 20 30 40
0
50
100
150
200
250
300
 1
 2
 3
 4
 5
L
o
a
d
 (N
)
Ex t e n si o n  (m m )0 10 20 30 40
0
50
100
150
200
250
300
350
 1
 2
 3
 4
 5
L
o
a
d
 (N
)
Ex t e n si o n  (m m )
0 10 20 30 40
0
100
200
300
400
500
600
 1
 2
 3
 4
 5
L
o
a
d
 (N
)
Ex t e n si o n  (m m )
102 
 
Table 35 Results after bursting strength test of inner layers 
 
 
         
(a) Film                                           (b) Bubble Wrap  
Figure 74 Load vs. Extension of inner layers 
 
 
S p e c i m e n
M a x i m u m  
L o a d             
( N )
E x t e n s i o n  a t  
M a x i m u m  
L o a d          
( m m )
M a x i m u m  
L o a d             
( N )
E x t e n s i o n  a t  
M a x i m u m  
L o a d          
( m m )
1 6 6 . 1 6 1 7 . 3 0 5 7 . 3 8 2 5 . 9 1
2 6 1 . 7 9 1 8 . 8 0 5 6 . 8 9 3 6 . 5 8
3 6 0 . 2 0 1 8 . 8 0 5 9 . 0 3 3 9 . 8 2
4 6 3 . 5 4 1 9 . 8 0 5 4 . 9 4 3 2 . 5 1
5 6 4 . 2 3 1 7 . 3 0 5 7 . 9 6 3 9 . 6 2
A v e r a g e 6 3 . 1 8 1 8 . 4 0 5 7 . 2 4 3 4 . 8 9
S t a n d a r d  d e v i a t i o n 2 . 2 9 1 . 0 8 1 . 5 1 5 . 8 3
C o n f i d e n c e  i n t e r v a l 1 . 6 8 0 . 8 0 1 . 1 1 4 . 2 9
B u b b l e  W r a pF i l m  
0 10 20 30 40
0
10
20
30
40
50
60
70
L
o
a
d
 (N
)
Ex t e n si o n  (m m )
 1
 2
 3
 4
 5
0 10 20 30 40
0
10
20
30
40
50
60
70
L
o
a
d
 (N
)
Ex t e n si o n  (m m )
 1
 2
 3
 4
 5