Damping of polymer composite materials for flywheel applications

Abstract

Damping of pure resin and T700/epoxy composite lamina in longitudinal and transverse directions were investigated experimentally and analytically. The effect of aging on damping was also studied by placing samples at 60°C in an oven for extended periods of time and using results from time-dependant studies. Damping master curves vs. frequency were constructed from individual curves at various temperatures using the match principle. Master curves constructed using Arrhenius equation matched those constructed using the match principle for the matrix but not for the composite. The damping response of the composite lamina was used to predict the response of laminate composites. It was found that for a specific frequency range, damping decreases with the increase in aging time, and that damping is dependent on the direction of fibers, highlighting the importance of multi-direction reinforcement for composite flywheel rotors. Laminate damping was also experimentally evaluated for a number of configurations (0°, ± 45° and 90°). The half power method was used to identify the damping characteristics for coupon samples. These experimental measurements matched results from lamina investigation and indicated that the 0° specimen has the lowest damping ratio in the fiber direction, while the highest damping ratio corresponds to the 45° fiber orientation. It was also observed that the damping factor was only weakly dependent upon frequency for a broad range of frequencies, which is an important result with regard to simulation and stability analyses. POLYM. COMPOS., 26:498–508, 2005. © 2005 Society of Plastics Engineers