Highly efficient continuous bistable nonlinear energy sink composed of a cantilever beam with partial constrained layer damping

This paper focuses on the transient nonlinear dynamics and targeted energy transfer (TET) of a Bernoulli-Euler beam coupled to a continuous bistable nonlinear energy sink (NES). This NES comprises a cantilever beam with the partial constrained layer damping (PCLD) and an end mass controlled by a nonlinear magnetostatic interaction force. The theoretical model of the nonlinear system is built based on the Lagrange equations and assumed-modes expansion method. A new parameter system damping ratio is proposed to evaluate the TET efficiencies. Impact experiments are carried out to verify the theoretical model and mechanisms. The results show that the bistable NES can achieve high and strongly robust TET efficiencies under broad-range impacts. The shear modulus of the viscoelastic layer, the length of the PCLD and the end mass have significant influences on TET efficiencies. Analyses of the TET mechanisms in the bistable NES show the following: steady transition of the stable state is an important reason for maintaining high TET efficiencies; nonlinear beatings can occur in high-frequency, fundamental and long-period subharmonic branches; and resonance captures featuring fundamental and subharmonic also help achieve rapid energy dissipation.