Experimental investigation of a buckled beam under high-frequency excitation

Abstract

In this paper, we investigate theoretically and experimentally dynamics of a buckled beam under high-frequency excitation. It is theoretically predicted from linear analysis that the high-frequency excitation shifts the pitchfork bifurcation point and increases the buckling force. The shifting amount increases as the excitation amplitude or frequency increases. Namely, under the compressive force exceeding the buckling one, high-frequency excitation can stabilize the beam to the straight position. Some experiments are performed to investigate effects of the high-frequency excitation on the buckled beam. The dependency of the buckling force on the amounts of excitation amplitude and frequency is compared with theoretical results. The transient state is observed in which the beam is recovered from the buckled position to the straight position due to the excitation. Furthermore, the bifurcation diagrams are measured in the cases with and without high-frequency excitation. It is experimentally clarified that the high-frequency excitation changes the nonlinear property of the bifurcation from supercritical pitchfork bifurcation to subcritical pitchfork bifurcation and then the stable steady state of the beam exhibits hysteresis as the compressive force is reversed.