Feasibility of measuring residual stress profile in differentself-pierce riveted joints

Abstract

The feasibility of measuring residual stresses in self-pierce riveted (SPR)joints by neutron diffraction technique was investigated. The main challengeinvolved dealing with the very small dimensions of SPR joints. Two differentjoints were examined: aluminium–steel and steel–steel. Even thoughsmall dimensions were involved, meaningful results were obtained. In the rivethead, tensile stress was observed for the steel–steel sample, whereasonly compressive stress was observed for the aluminium–steel. The residualstress in the rivet head was higher at the centre and lower at the edge forboth joints. Stresses in the sheet material beside the rivet wall and at adistance of three times the rivet radius from the rivet axis were not significant.For the SPR joints examined, the maximum value of residual stress was compressiveand occurred in the rivet leg. The results are discussed according to thephysical events involved during the process.