Fatigue strength evaluation methods for spot welding are studied by the fatigue test of an actual car body. The following results were obtained from the test. (1) The configuration of fatigue fracture on spot welds around the window corner near the supported point of a car body is in fair agreement with those of structural component models of the window corner. (2) The abovementioned fatigue strength of spot welds can be evaluated by (a) the carrying-load values of spot welds based on FEM analysis and by (b) the values of typical stresses measured around the spot weld. Judging from the test results, it was proven that the fatigue strength of spot welds in an actual car body against cyclic load can be estimated by the results of the fatigue test of test pieces and structural component models which were previously reported by the authors.
