Targeted energy transfer (TET) is the essence of nonlinear energy sink (NES) to suppress the vibration of a primary system. The TET, however, can only be triggered above a threshold level of the excitation energy. For systems exhibiting small-amplitude vibrations and uncertain intermodal frequency distributions across multiple modes, elucidating the energy transfer mechanisms within the coupled systems has been a long-lasting challenge. Based on an experimental test bench consisting of a simplified automotive body panel with a NES, this paper investigates the intermodal energy transfer and the suppression of small-amplitude vibration dominated by two structural modes. Upon establishing the corresponding dynamic model, numerical analyses are conducted. The energy flow among the coupled system’s degrees of freedoms is scrutinized, with the vibration suppression effectiveness quantified in terms of the frequency ratio. It is shown that two closely spaced modes (with a frequency ratio close to one) can be indirectly coupled through the NES, thus entailing energy transfer from lower- to higher-order modes within the primary system. When the two modes are well separated, however, TET can be triggered through the coupling between the NES with only one mode, without intermodal energy transfer.
Shao et al. (Tue,) studied this question.