Stress Intensity Factors of Surface Crack of Hollow Axles under Rotary Bending

Stress intensity factors(SIFs) calculations for circumferential external surface semi-ellipse crack in hollow axles subjected to rotary bending loads using a 3D finite element model are presented. The three-dimensional finite element is carried out to obtain the displacement field of the crack front by employing quarter-point 20-node isoparametric degenerate singular elements. The semi-ellipse crack configuration are defined with two parameters: the aspect ratio a/b (a and b are ellipse semi-axes), the relative depth a/t (t, the wall thickness of the hollow axle). An analysis of the influence of the rotary angles on SIFs during a rotary bending load cyclic at the crack front is presented. Results have shown For a given position along the crack front the SIF gets to its minimum for theta =90 degrees. Similarly, the values of SW decrease with the aspect ratio increases at a given depth. Moreover, the curves change from protruding shape to concave ones with the aspect ratio from small to big.