Abstract
Recently, a new issue in design of spot welded structures such as the automobile and train car bodies is prediction of a systematic fatigue design criterion. In general, the most typical and traditional method is the use of the Ä P - Nf curve. However, since the fatigue data on the curve varies according to welding conditions, materials, geometry of joint and fatigue loading conditions, it is necessary to perform the additional fatigue tests for determining a new fatigue design criterion of spot-welded lap joint having different dimensions and geometry. In this study, the stress distribution around spot weld of various spot welded lap joints such as in-plane bending type (IB type), tension shear type (TS type) and cross tension type (CT type) was numerically analyzed. Also, using these results, Ä P - Nf curves which were previously obtained from the fatigue tests for each type of them were rearranged in to the Äó -Nf relations with the maximum stresses at the nugget edge of spot weld.