Moreira A., Flowers G.

An investigation of the nonlinear characteristics of the internal damping of graphite fiber-epoxy composite materials for use in flywheel components is presented. Special attention is given to the dependence of vibration damping on the displacement amplitude and natural frequency of the test articles. These consisted of thin composite beams in a fixed-fixed configuration and where one of the edge fixtures could be shifted and fastened within a range of positions, stretching the sample so as to vary the first natural frequency. The characteristics of a series of vibration decays at the first natural frequency obtained experimentally were studied, showing clear patterns of relation between the amplitude of vibration at each frequency and the vibration damping. Changes in the natural frequency of vibration with decreasing amplitude were addressed as well. Linear and nonlinear lumped-parameter system models were designed and assessed in terms of accuracy and functionality. The optimal models of vibration damping obtained can be implemented in more complex models for flywheel systems simulation, in order to enhance the reliability of the stability thresholds predicted.