Evaluation of residual stress in SPR joint by neutron diffraction

Abstract

The feasibility of measuring residual stresses in Self-Pierce Riveted (SPR) joints by neutron diffraction was evaluated in this study. Despite the small dimensions involved, meaningful results were obtained. It was observed that residual stress in the rivet head was higher in the centre and lower at the edge. For the SPR joints examined, the maximum value of residual stress evaluated was 550MPa, compressive and occurred in the rivet leg. Stresses in material adjacent to the rivet wall and at a distance of three times the rivet radius from the rivet axis were not significant. The results are discussed with respect to the physical events involved during SPR.