Prediction of crack shape in a cylindrical bar under combined fatigue tension and torsion loading

Abstract Most of the existing theoretical studies to predict 3D-crack-front shape change are confined to plate-like structures. In this paper, a transient three-parameter geometric model with fewer constraints located on equivalent deflected crack planes is developed by using space oblique extension circles for a transverse surface crack in a solid round bar under fatigue tension-torsion loading. The results show that the proposed mathematical and numerical analysis method can get more effective prediction with fewer iterations. It is verified by comparing the formation outcome of crack growth obtained by visualization of the predicted crack-front shapes with other numerical solutions and experimental results.