Vibration absorption of parallel-coupled nonlinear energy sink under shock and harmonic excitations

Nonlinear energy sink(NES)can passively absorb broadband energy from primary oscillators.Proper multiple NESs connected in parallel exhibit superior performance to single-degree-of-freedom(SDOF)NESs.In this work,a linear coupling spring is installed between two parallel NESs so as to expand the application scope of such vibration absorbers.The vibration absorption of the parallel and parallel-coupled NESs and the system response induced by the coupling spring are studied.The results show that the responses of the system exhibit a significant difference when the heavier cubic oscillators in the NESs have lower stiffness and the lighter cubic oscillators have higher stiffness.Moreover,the efficiency of the parallel-coupled NES is higher for medium shocks but lower for small and large shocks than that of the parallel NESs.The parallel-coupled NES also shows superior performance for medium harmonic excitations until higher response branches are induced.The performance of the parallel-coupled NES and the SDOF NES is compared.It is found that,regardless of the chosen SDOF NES parameters,the performance of the parallel-coupled NES is similar or superior to that of the SDOF NES in the entire force range.