Experimental and XFEM modelling of high cycle fatigue crack growth in steel welded T-joints

The current paper reports the results of a series of high cycle fatigue (HCF) experiments on steel welded T-joints, tested under constant amplitude three-point bending. The eXtended Finite Element Method (XFEM) was then implemented to simulate the experiments. The crack and its growth were characterised by means of level set functions to eliminate the need for re-meshing. The study can be viewed as a first-of-its-kind in XFEM fatigue simulation of butt welded steel T-joints; where the crack geometry and growth is essentially three dimensional, making the problem particularly acute. The XFEM/fatigue crack growth (FCG) procedure employed in the study was first validated against constant amplitude HCF experiments on notched steel plates from other researchers. The same modelling procedure was then used for simulating the fatigue tests conducted on steel welded T-joints. It was found that the XFEM predictions for the crack growth, the growth rate, number of cycles to failure, crack shape and final crack size were satisfactorily comparable to those obtained in the experiments. Mean errors in the XFEM predictions for the fatigue life ranged from -20.7% to +0.9%. The morphology of the fracture surface from the numerical model, in general, had a good agreement with the corresponding experimental morphology.