Fatigue prediction of spot welded joints using equivalent structural stress

The author proposes a fatigue prediction method for spot welded joints in automotive body structures using an equivalent structural stress at the edge of spot welds. The proposed fatigue prediction method is developed by substituting the stress components in von Mises equation to the local structural stresses at the vicinity of spot weld. The structural stresses at the edges of the weld nugget in each sheet are calculated using the forces and moments that are determined by finite element analysis. The equivalent structural stresses are correlated to experimental fatigue data to predict fatigue life of the spot welded joints. The proposed method is evaluated with two different experimental fatigue data of spot welds and shown good correlation with fatigue test results.