Discussion on isolation of flexible beams with various support configurations

Abstract

This work discusses the strain and acceleration suppression of a flexible beam subjected to different supports analytically. As classical protection, the beam is mounted on a vertical linear spring together with a linear damper in parallel. This is called linear isolation. To enhance isolation performance, nonlinearity is employed in the boundary. In addition, quasi-zero isolation is established based on the non-linearly enhanced one by adjusting the installation length of the horizontal spring. To discuss their performance fully and fairly, the amplitude, the acceleration, the potential energy of the beam, the input work of the excitation, the dissipation work of the beam, and the dynamics stress along the beam are investigated based on the same parameters. The comparison shows that all these isolations can protect the beam with high efficiency, even when the basement excitation is tiny. Although the linear isolation and the nonlinearly enhanced one will arouse two resonance peaks on both sides of the primary resonance of the beam without isolation, the maximum amplitudes of them are reduced a lot. But for the low frequency excitation, the quasi-zero isolation has the best performance as it drives the primary resonance to the high frequency region. The simulation shows that the beam needs a relatively soft isolation to avoid the damage caused by the shock vibration, including the quasi-zero one. In general, the quasi-zero isolation shows the best performance. The nonlinearly enhanced one is the suboptimal choice. The present work shows the capacities of three isolations for a flexible beam by the steady-state response and the shock vibration. It provides design suggestions for the isolation of flexible beams.