Mechanical behaviour of bistable struts

The mechanical behaviour of a bistable structural element, which is based on the snap-through and bifurcation properties of the von Mises truss, has been investigated in this article. By assuming the joint behaviour as ideal hinges and using the large deformation theory based on a linear elastic material, a simple analytical model for the stability of the von Mises truss was formulated. The governing set of non-linear equilibrium equations was obtained by applying the principle of stationary total potential energy. Then, the formulae of the snap-through and bifurcation buckling loads and the equilibrium path were given. In addition to the well-known cases of primary and secondary branches, a third type that the bifurcation buckling point lying on the descending branch of the load versus displacement curve was discussed. In this case, although its upper bifurcation load is lower than its upper snap-through buckling load, the truss experiences a symmetric snap-through mode first, and hence the bifurcation point is not physically relevant. Finally, the assumptions of the classical von Mises truss analysis are discussed.