Large Amplitude Nonlinear Response of Flat Aluminum, and Carbon Fiber Plastic Beams and Plates

This progress report presents the results of a continuing study to improve the understanding of nonlinear dynamic behavior of aerospace structures subjected to high levels of excitation. Tests were continued with a clamped- clamped C-C aluminum beam. A summary of the results is presented. Tests were conducted with a C-C carbon fiber reinforced plastic CFRP beam and a pinned- pinned P-P aluminum beam. A summary of these results is also presented. Flat plate tests began with an aluminum plate. The shapes of the total, axial and bending strain power spectral densities for the C-C aluminum and the CFRP beams were quite similar. Both showed a small frequency increase and slight peak broadening as the levels of excitation increased. The nonlinear displacement shapes for the two cases were also quite similar. Further analysis is needed for the P-P aluminum beam case. Finally, a method of estimating the RMS stress for the multimodal response of a panel is presented. Nonlinear vibration, Sonic fatigue, Clamped beams, Clamped plates, Dynamic testing, Dynamic analysis