NONLINEAR FREE VIBRATIONS OF SPIDER WEB STRUCTURES

摘要

Most research into natural spider web structures have considered only the small deformation theory based on small amplitude analysis. In reality, spider web structures, which are slender by nature, are more prone to large-amplitude load effects. This paper firstly presents a numerical study into large amplitude free vibrations of spider web structures. Highly coupled geometry and material nonline-arities have been formulated to establish the finite element models of spider web structures. Validation of the model has been carried out using previous research studies into spider web vibrations. Excellent agreement has been obtained for linear and nonlinear perturbation results. The validated FEM has been further extended to investigate the large amplitude effect on natural frequencies and corresponding mode shapes of highly-slender spider webs. Interestingly, this is the world first to report the dynamic softening and hardening phenomenon in the slender spider web structures. The insight into nonlinear dynamics of slender thin membrane skeleton structures can be used not only for better understanding the nature, but also for improving functionalities of defense technology using ultra-thin plates and shells.