Theoretical and Experimental Analysis of Strain in a Tire Under Static Loading and Steady-State Free-Rolling Conditions

Abstract

This main objective of this work is to predict the operating conditions or the state of a tire based on a wireless sensor suit. First a three dimensional finite element model of a standard reference test tire (SRTT) was developed to better understand the tire deformation under separate cases of static loading, steady state free-rolling and steady-state rolling conditions. A parametric study of normal loading, slip angle and slip ratio was carried out to capture the influence of these parameters. The numerical analysis techniques such as the Fouier analysis, Weibull curve fitting and slope curve method were explored to relate the tire strains to the various loads on the tire. The advantages and disadvantages of the various methods, mentioned above, for strain analysis is also presented.

A wireless sensor suite comprising of analog devices (strain, pressure and temperature sensors) was developed to capture the tire deformation under loading conditions similar to those used in the finite element model. This sensor suite formed the basis for experimentally verifying the trends captured by the finite element model on a custom built tire test stand with capabilities of mimicking real-time conditions (under static loading scenario) of a tire in contact with road and steady state conditions on a FlatTrac test bed. Using the results from the experiments and the finite element model an empirical model was developed which demonstrates how the strains measured on the inner surface of the tire could be used to quantify desired parameters such as slip angle, lateral force, slip ratio, longitudinal force and normal load. This resulting empirical equations relate measured strains to the normal load, slip angle, slip ratio, lateral force and longitudinal force.