Abstract
Thin-shell structured beams are much utilized in the recent automobile design to achieve the good level safety and the lightweight solution for the environment problem. The present paper aims to comprehensively research the impact rate dependence of the elastic unstable behaviors observed in such a thin-walled member in reference to Karman's effective length and Euler's buckling. Rectangular beam has quite strong impact rate dependence; at high impact rate, reaction subtracting the inertia force coincides with the uniform yielding of total cross section. Meanwhile, at low impact rate, Karman's effective length is found to become good approximation for practical usage, but the dynamic Euler's buckling should be more important to explain the deeper mechanism.
