Experimental investigation into dynamics of flat and bistable plates

Bistable plates have two stable states between which they may 'snap', and are attracting interest in the field of adaptive structures. This work presents results of an experimental investigation into the vibrations of both flat and bistable composite plates with free edges, employing a novel video method to capture the full field of vibration in 3 dimensions. For flat plates, it is shown that deflection shapes of vibration can transform from the mode shape as amplitude is increased, and that at certain frequencies two deflection shapes can be achieved depending on initial conditions. For bistable plates, it is noted that lower vibration modes can be linear up to moderate amplitudes, whereas at high amplitude highly nonlinear 'snapping' oscillations are shown. We discuss these effects in terms of the anisotropic stiffness of CFRP, and the geometric coupling between doubly-curved out of plane deflection shapes and in-plane deformations.