On the dynamic buckling of a simple elastic-plastic model

In order to provide some insight into the phenomenon of dynamic plastic buckling, the response of an imperfection-sensitive idealised model with elastic-plastic springs to simulate material plasticity was examined using theoretical and numerical methods. The theoretical method predicts that dynamic plastic-elastic buckling governs the response for small imperfections, while dynamic instability occurs elastically for large imperfections. Furthermore, the dynamic buckling load of a model with small imperfections is larger than the corresponding static buckling load because of the different elastic-plastic deformation histories in the springs during the static and dynamic responses. The numerical study reveals two distinct forms of dynamic response known as "direct" and "indirect" dynamic buckling which occur within specific ranges of the parameters. The various results presented herein indicate that dynamic plastic buckling is imperfection-sensitive particularly for "direct" dynamic buckling.