Stress Intensities Derived from Stresses Around a Spot Weld

The stress intensities (stress intensity factors and J-integral) around a spot weld between sheets of dissimilar materials and different thicknesses are generally expressed by the local stresses around the spot weld. The derivations are established on an interface crack model which represents the radial cross-sections of the spot weld with the local stresses varying from point to point along the periphery of the nugget. The J-integral is determined analytically by applying the equilibrium conditions and the elementary plate theory to the model. The stress intensity factors are then separated by following a load decomposition procedure and an analytic solution to interface cracks. The thermal stress intensities are also obtained for the spot weld. Application examples are given for a tensile-shear specimen.