Axially crushed square tubes with corrugated surface

In this paper, elastoplastic nonlinear behaviors of square tubes with corrugated surface subjected to axial compression are studied by using finite element method. The effect of corrugation is to control the deformation pattern and to decrease the fluctuation in the load-displacement curve for square tubes. It is found from numerical results that the deformation mode corresponding to the corrugation can be classified into axisymmetric mode and non-symmetrical mode, and the axisymmetric mode is classified into progressive crush mode, in which compressive force vibrates with the folds forming one after another, and simultaneous crush mode, in which compressive force increases uniformly. These features are the same as that of the case of cylindrical tubes with corrugation. However, it is more difficult, in square tubes than in cylindrical tubes, for crushing deformation to occur in accordance with the given corrugation because of the existence of corner parts. A mode classification chart is produced for various conbination of wavelength 2λ and amplitude a. Also, it is found that the average stress in crushing of square tubes with corrugation is not mostly dependent on the corner radius in approximation.