Plastic Bulge and Energy Absorption of Stepped Circular Thin Pipe

Load carrying capacity and energy absorption of plastic bulges of stepped pipes enlarged by dies at the edge are investigated in this paper. The pipes are enlarged by dies and then compressed axially on the edge in the experiment. Relations between load and displacement, and the deformation process of plastic bulge are examined in the experiments. The process of enlargement by a die and compression are simultaneously analyzed by finite element analyses. The load-displacement relations and the deformation modes predicted by finite element analyses are in good agreement with the experiments. The energy absorption ability in monotonic increasing load and cyclic varying load are also estimated by analyses. In the deformation process of a moving plastic bulge the constant load carrying capacity is obtained.