A new approach for the simulation of fatigue crack growth in welded joint has been developed and the concept has been applied to welded cruciform and curve T-joints. The phenomena of crack propagation and interface debonding can be regarded as the formation of new surface. Thus, it is possible to model these problems by introducing the mechanism of surface formation. In the proposed method, the formation of new surface is represented by interface element based on the interface potential energy. The properties of this interface element represent the bonding strength of the material. As the cyclic load continues, the bonding strength decreases between the interacting surfaces and the crack propagates slowly. Based on this concept, an ANSYS code has been written for the simulation of crack propagation. Using this code, fatigue crack growth rate and fatigue crack propagation life of 2-D FEM models of welded cruciform and curve T-joints for different stress/load ratios have been analyzed and presented in this paper. The method is relatively simple compared to other conventional FEM method and save computer time significantly. The predicted results are compared with experimental results and good agreement has been achieved.

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