Nonlinear vibrations from local shell buckling in composite tape spring hinges

The nonlinear steady-state responses for a thin-shelled composite tape spring hinge under translational base harmonic excitation are characterized both experimentally and through finite element analysis. The motivation is to investigate how the nonlinear elastic deformation modes associated with pre-buckled and post-buckled stability regimes manifest into dynamic responses when a tape spring shell is subject to large amplitude vibrations. The first two linear vibration modes are found to be a twisting mode and a bending mode in both high-speed digital image correlation tests and finite element analysis. Forward and backward frequency sweeps across the dominant bending mode are then experimentally conducted with a shaker setup and through nonlinear dynamic implicit simulations in Abaqus. The hinge structure is found to exhibit broadband nonlinear steady-state responses consisting of flexural-torsional, subharmonic, superharmonic, and chaotic oscillations as well as intermittencies. There is correlation between the experimental and simulation results in terms of the steady-state amplitudes and frequency content, nonlinear bandwidths, and response type. A detailed characterization is made for each observed response by visualizing both global and local deformations for the tape spring hinge.