Nonlinear energy sink with limited vibration amplitude

Abstract

In the research of applying nonlinear energy sinks for vibration reduction, usually the vibration amplitude of nonlinear energy sinks is not limited. Since the linear stiffness of the nonlinear energy sink is zero, the vibration amplitude of the nonlinear energy sink may be very large. This is obviously not acceptable in many mechanical engineering fields. Based on theoretical and experimental investigations, this paper investigates a limited nonlinear energy sink by using a piecewise spring device. Thus, the vibration amplitude of the nonlinear energy sink can be restricted from being too large. For free vibration, the effects of the piecewise stiffness and the gap width on the vibration responses of the nonlinear energy sink and the primary system, i.e. the linear oscillator, are profoundly examined. The numerical results show that the vibration of the nonlinear energy sink is effectively suppressed. Nevertheless, the vibration damping effect of the nonlinear energy sink on the linear oscillator is weakened after the introduction of the piecewise spring. However, after improving parameters reasonably, the nonlinear energy sink can still achieve considerable damping effects. In addition, the experimental results are conducted to verify the theoretical results. Moreover, the particle swarm optimization algorithm is used to optimize the piecewise stiffness and the gap width so that the vibration of the linear oscillator is suppressed most efficiently. The optimized results are verified with the differential evolution algorithm to illustrate that the particle swarm optimization is effective and accurate. In conclusion, this work provides useful information for the design of the nonlinear energy sink and can promote the engineering application of the nonlinear energy sink.