Lateral vibration control of a beam subjected to the harmonic external load using a nonlinear energy sink

Abstract

Annihilating of unwanted vibrations of mechanical systems is one of the necessary requirements of designers over years. This current paper investigates dynamical behavior of a clamped-clamped beam attached to a Nonlinear Energy Sink (NES) under the harmonic force with different amplitudes. The nonlinear absorber consists of a linear damper and an essentially nonlinear stiffness. The considered system is a simple model of offshore structures subjected to the external fluid flow. In order to simulate the primary system, Euler-Bernoulli beam theory has been applied. Occurrence of Strongly Modulated Responses (SMR) under sinusoidal load reflects the efficiency of the absorber. Analytical approach (complexification-averaging method) and numerical solution (Runge-Kutta method) are applied for comparison and validation of the results. The boundaries of occurrence of Saddle-node and Hopf bifurcations and relaxation oscillations are obtained. The results show that the NES damping has substantial influence on the NES performance. Furthermore, by approaching the NES location to the beam supports, the probability of occurrence of the SMR decreases and the transient responses of the system lasts longer.

Keywords

• clamped-clamped beam
• nonlinear energy sink
• strongly modulated responses
• relaxation oscillations
• phase plane