Host: The Japan Society of Mechanical Engineers
Name : [in Japanese]
Date : September 03, 2017 - September 06, 2017
From the viewpoint of improving both the crash safety and the fuel efficiency, various shaped thin-walled structures have been utilized as energy absorbers of automobiles such as crash box, front side member and so forth. In order to effeciently absorb energy in the crash, those are asked to have appropriate strength/weight ratios for respective materials and structures. In this study, impact (3~4m/s) crushing tests of some thin-walled regular polygonal tubes were performed by the drop weight testing device for crush angles of 0, 10, 15, and 20° to investigate the transition from the axial collapse mode to the bending one. The specimen material is annealed S25C that shows high strain rate dependence. This transition occurred at the crush angle around 15° for square and regular pentagonal tubes. The transition causes abrupt decrease of the mean buckling load, which is no longer so sensitive to the crush angle under the bending collapse mode. The comparison with the results of quasi-static and low-speed crushing tests also shows that the mean buckling load under the axial collapse mode considerably increases with the strain rate, while that under the bending one hardly grows.
