Intermodal targeted energy transfer (IMTET) in a model with multi-stability

The paper addresses the phenomenon of intermodal targeted energy transfer (IMTET), i.e., an intensive redistribution of the oscillatory energy among the system modes beyond any resonance conditions. The IMTET allows substantial mitigation of the external excitations through more efficient use of the internal damping capabilities of the system. Contrary to previously explored designs based on impacts or contacts/clearances, the setting under consideration comprises smooth bistable elements. This modification aims to avoid extreme accelerations and loads related to the impacts. A simple benchmark system with two masses supported by two bistable elements capable of snap-through dynamics, is explored numerically in conditions that mimic a shock excitation. The results demonstrate that above certain excitation threshold, the bistable elements activate the strongly nonlinear interactions inside the system. As a result, one can observe a multi-fold decrease of the characteristic damping time of the structure. This enhancement of the damping capability is achieved due to a synergy between activation of antisymmetric and localized modes in conditions of the symmetric shock-like excitation.