INELASTIC ANALYSIS OF THIN-WALLED TUBES UNDER CYCLIC BENDING

Thin-walled circular tubes under bending have been shown to ovalize. For tubes bent into the plastic range, part of the ovalization is permanent. It has been demonstrated experimentally that reverse bending and subsequent repeated cyclic bending cause a gradual growth of ovalization. This paper presents a virtual work-type of formulation of the problem in an attempt to analytically predict the growth of ovalization for tubes cycled in pure bending. A number of nonlinear-hardening plasticity models are used in the formulation. The problem solution is found to be sensitive to the choice of hardening rule used.