Numerical simulations of dynamic instability of elastic-plastic beams

This paper numerically investigates the dynamic instability of different elastic-plastic beams subjected to transverse pulse load. Two types of beam dynamic instability, i.e., symmetrical and asymmetrical instabilities, are studied. The unstable responses of the elastic-plastic beams are illustrated by investigating the modal participation factors of the lowest nine vibration modes, which are determined by inverse derivation of the numerically simulated beam deflection response. The critical pulse loads for the beam symmetrical and asymmetrical instabilities are obtained with respect to different load durations. Characteristic diagrams for beams with different boundary conditions and subjected to different type pulse loads are given. The present study conforms that not only axial compressive load induces instability of slender members, but also transverse pulse load results in instability of elastic-plastic beams. © 2006 ASCE.