XFA3D Toolkit for Fatigue Damage Assessment of Welded Aluminum Structures under Variable Amplitude Loading

This paper presents an overview of our recent enhanced 3D extended finite element toolkit for Abaqus (XFA3D) for fatigue damage assessment of welded aluminum structures under block loading. To alleviate the computational burden associated with the insertion and propagation of arbitrary cracks in the presence of a welding induced residual stress field, a nodal enriched displacement field coupled with a level set description is integrated with a hybrid implicit and explicit crack representation approach. A simplified residual stress characterization is implemented without invoking two separate analyses during each step of the crack growth. A stress ratio dependent fatigue damage accumulation model is employed for the fatigue damage accumulation under an arbitrary multi-block loading spectrum. Capability demonstration is performed first for simulation of curvilinear fatigue crack growth prediction in a holed plate and a multi-hole beam followed by its application to three welded components with an initial flaw including a butt welded tensile specimen, a cruciform tensile specimen with a semi-elliptical surface flaw, and a welded T-joint with a through-the-thickness crack.