Recent Developments in Analysis and Testing of Spot Welds

The recent developments in analysis and testing of spot welds are briefly reviewed in general and the solutions, stress formulas and strain gauge techniques that may be applied to the analysis and testing are elaborately introduced in particular. The local stress parameters such as notch stress, stress intensity factors and J-integral at a spot weld are generally expressed by the structural stresses around the spot weld. The determination of these parameters are then simplified as determining the structural stresses that can be calculated by a spoke pattern for spot welds in finite element analysis. The approximate stress formulas for the structural stress, notch stress and stress intensity factor are given for common spot-welded specimens. With the aid of the formulas the test data in terms of the original load can be easily transformed into the data in terms of the structural stress, notch stress or stress intensity factor at the spot weld. The formulas also facilitate the transfer of the test data across different specimens. The strain gauge technique developed for a tensile-shear specimen shows that all the structural stress, notch stress, stress intensity factors and J-integral at the spot weld can be determined by two strain gauges attached only to the outer surface of one sheet. The results presented here should be helpful for the analysis and testing of spot welds and for developing measuring methods for spot welds.