On the stability of structures under impact loads

In this paper, the complete stability analysis of a simple structure under dynamic impact loading is presented. It is considered as a system of two articulated rigid bars originally with a common straight axis attached to a fixed pinned support at one end and a movable pinned support at the other end. A linear spring is connected to the central articulation and it is inclined with respect to the original common axis of the bars. It is well known that this kind of structure will exhibit an asymmetrical bifurcation stability pattern under a static load applied in line with the pinned supports. In the present study, the load is dynamic, suddenly applied, and large displacements are considered. Three cases are discussed with respect to the duration of the loading: short duration, finite and infinite duration. In all cases, theoretical critical loads are obtained and the influence of imperfections is also analysed.