Characterization and Dynamic Analysis of Damping Effects in Composite Materials for High-Speed Flywheel Applications

Abstract

The directional mechanical properties of carbon fiber reinforced composite materials make them suitable for components of flywheel energy storage systems. Particularly the hub-rim interface is a component where fiber reinforced composite materials can be applied to reduce rotor mass to achieve high energy densities. However, these materials can introduce significant flexibility and damping into the system, that raise stability issues. This research work consisted of an investigation of the material damping of carbon fiber reinforced epoxy composites and a study of the effect of the material damping on the stability of composite high speed flywheel rotors. In order to characterize the damping of the composite material, a number of beam samples, cut from laminate plates in various configurations, were tested under several boundary conditions. Different methods were used for the extraction of the desired characteristics. The results are presented, described and detailed in this dissertation. A prototype of a flywheel rotor was also examined to determine the amount of damping of its composite hub-rim interface and compare these results with the ones of the tests on laminate beams. In addition, a model that captures the main features of flywheel systems was developed, and different configurations were simulated to determine the main factors governing stable ranges of operation. It was observed that some inherent features of flywheel systems allow assumptions that greatly simplify the analysis of the model. Parameter variation studies are presented and discussed in detail. Substantial insight into factors that govern the stability of this kind of high speed rotor system was obtained.