Open Access

ARTICLE

Finite Element Modeling of Fatigue Crack Growth in Curved-Welded Joints Using Interface Elements

M. S. Alam¹, M.A. Wahab^1,2

1 Department of Mechanical Engineering, Louisiana State University, Baton Rouge, LA 70803, USA
2 Corresponding author. Tel.:1- 225-578-5823, Fax:1- 225-5785924, E-mail: wahab@me.lsu.edu

Structural Durability & Health Monitoring 2005, 1(3), 171-184. https://doi.org/10.3970/sdhm.2005.001.171

Abstract

Fatigue life of curved structural joints in ship structures under constant amplitude cyclic loading has been studied in this research. A new approach for the simulation of fatigue crack growth in welded joints has been developed and the concept has been applied to welded curved butt-joints. The phenomena of crack propagation and interface debonding can be regarded as the formation of new surfaces. 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 surface 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 starts to propagate slowly. Based on this concept, an ANSYS input file has been written for the simulation of crack propagation in the curved welded butt-joints. Using this code, the fatigue crack growth rate and fatigue crack propagation life of 3-D FEM (finite element method) models of welded curve butt-joints and 2-D models for T-joints for different stress/load ratios have been analyzed. The variations of crack-opening-displacement (COD) and crack- tip- strain over crack-tip- stress have also been calculated. For the validation of the simulation, experiments have been conducted and generally good agreement has been achieved. The simulation method is relatively simple compared to other conventional FEM method and effective in many applications.

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