Shape growth simulation of surface cracks in tension fatigued round bars

The step-by-step three-dimensional finite element technique, developed recently by the present authors, was used to simulate fatigue crack shape developments, beginning from several elliptical-arc cracks with different aspect ratios and an irregular crack, in round bars under axial tension. A Paris type crack growth relation was employed as the basis of the simulating computations. The shape of growing cracks was quantitatively examined by two proposed measures: the relative residual and relative standard deviation, in order to reveal the shape difference between the numerically predicted crack profiles and the widely-assumed circular-arc shape. The aspect ratio changes for the initially part-elliptical cracks were predicted, and compared with some published experimental results. In addition, the effect of the exponent in the Paris law on the aspect ratio variation was investigated. (C) 1997 Elsevier Science Ltd.