Fatigue Properties of Spot Welded and Spot Weld-Bonded Joints of Steel Sheet

Abstract In this paper, fatigue tests are carried out on spot welded and spot weld-bonded joints of mild steel and ultra-high strength steel plates. The fatigue strength of the spot weld-bonded joints is higher than that of the spot welded joints. On the spot weld-bonded specimens, the strain distribution around the bonded area during fatigue tests is measured by using strain gauges to investigate the interfacial debonding behavior of adhesive bonding. According to the strain distribution measurement, the debonding initiates from the edge of the adhesive bonding, and propagates to the spot weld nugget. The fatigue strength is improved because the stress concentration of the nugget edge is considerably reduced in large part of fatigue life.