Nonlinear experimental dynamics of a pentastable composite cantilever shell

A composite shell with conical geometry, featuring opposite curvatures in its free (undeformed) configuration, is studied. Prestress is applied by first flattening and then clamping one of the curved edges, leading to a morphing structure. The shell exhibits five distinct static equilibria, referred to as configurations I, J, L, S, and I∗. Based on experimental measurements and numerical models, the rich potential energy topology is qualitatively reconstructed. The linear dynamics of the cantilevered shell is investigated at first through various scenarios of kinematic excitation over a wide range of frequencies (up to 100 Hz). Frequency response curves, time series, phase portraits, Poincaré maps, fast Fourier transforms and largest Lyapunov exponents are used to investigate in-well, cross-well, and global nonlinear dynamics. Depending on the forcing amplitude and frequency, one-way and reversible snap-through is observed. The extensive experimental campaign allows to unveil the dynamic interplay among the observed five stable configurations.