Buckling transition of axially impacted open shells

The transition between global and progressive buckling is explored in this paper for three different open cross-section shells. The shells were simply supported or clamped at the bottom and were submitted to axial quasi-static loads and to the impact of different drop masses. The experiments were complemented by a detailed finite element analysis, which required a quasi-static material characterisation based on tensile and three point bending tests. It was found that buckling transition from a global to a progressive mode cannot be clearly characterised for these open shells by considering only the overall final bucking shape. Using the finite element analysis, a more meaningful parameter to indicate the collapse mode, the specific energy, was calculated, allowing a better distinction among the most crashworthy profiles.