The Elastic-Plastic Response of Thin-Walled Tubes Under Combined Axial and Torsional Loads: Part II—Variable Loading

Abstract

This paper continues the investigation of the elastic-plastic response of thin-walled tubes subjected to combined axial and torsional loads. The stress-strain loop under arbitrary variable loading is first discussed. It is then shown that due to the kinematic hardening, a steady state, either one of the reversed plasticity or one of the elastic shakedown, can always be reached under cyclic loadings, with a hysteresis loop in the form of a parallelogram or a straight line. As a result, the difference in response between nonproportional and proportional loading will finally disappear. The investigation indicates that the simple kinematic hardening rule is able to describe, at least qualitatively, certain basic characteristics of the material behavior observed in nonproportional tests.