Formability assessment of plastic joining by compression instability for thin-walled tubes

Abstract

A new approach of plastic joining two thin-walled tubes by compression instability was investigated in this work. Numerical simulation of the whole deformation process of the plastic joining was performed. Experiments of plastic joining by compression were conducted. The influence of some geometrical parameters on the joint mode was discussed in detail. The force-displacement response of the tubes subjected to axial compression was analyzed. The main deformation characteristic of each stage was described. The strength of the joint under uniaxial tension was assessed by simulation. The formability of the tube joining by plastic instability was assessed from three aspects. The results showed that there were three joint modes in tube joining processes, immature joint, qualified joint, and unqualified joint, which was dependent on the ratio of the free length with radius. The chamfer angle of the tube ends played an important role in the plastic deformation amount of the tubes. The formability of the tube plastic joining by compression instability could be assessed by geometrical parameters of the tubes, the compatibility of two wrinkles induced by compression and the plastic deformation amount of the tubes. The strength of the joint was highly dependent on the wrinkles’ geometry.