Vibro-impact spring-pendulum nonlinear energy sink

Abstract Several types of nonlinear energy sinks have been proposed in the literature for shock and seismic vibration mitigation of dynamical structures. Accordingly, this study proposes two nonlinear energy sink (NES) configurations that incorporate single-sided vibro-impact with an inclined barrier into a pendulum tuned mass damper (PTMD) and a spring-pendulum vibration absorber. The first proposed design, the impact-pendulum with rigid arm NES (IP-RA NES), is a modified version of the PTMD. The second design, the impact-pendulum with an elastic arm NES (IP-EA NES), is a modified version of the spring-pendulum vibration absorber. The proposed designs leverage the synergy between inertial coupling nonlinearity and non-smooth vibro-impact nonlinearity. Mathematical models are developed in dimensionless form, and the parameters of the two proposed NESs, the PTMD, and the spring-pendulum vibration absorber are optimized using an optimization solver based on the derived equations of motion, enabling a fair and informative comparison and analysis. The optimal energy dissipation achieved by the two modified absorbers is found to be more robust to deviations from the optimized parameters than that of the PTMD and the spring-pendulum absorber. Furthermore, the IP-EA NES demonstrates the highest resistance to parameter deviations. The response results obtained from numerical simulations demonstrate that, in both proposed configurations, collisions of the NES mass with the inclined rigid barrier significantly contribute to energy dissipation, alongside torsional damping. Additionally, radial damping in the IP-EA NES makes a notable contribution to energy dissipation. Performance comparisons with the PTMD and the impact-free spring-pendulum absorbers verify the robustness of the IP-RA and IP-EA NESs in maintaining optimal energy dissipation under both impulsive and seismic inputs to the LO. However, under seismic ground excitation, the IP-EA NES achieves the highest level of vibration suppression among all the considered absorbers.