AN IMPROVED NUMERICAL TECHNIQUE FOR SIMULATING THE GROWTH OF PLANAR FATIGUE CRACKS

This paper describes a versatile technique for simulating the fatigue growth of a wide range of planar cracks of practical significance. Cra ck growth is predicted on a step-by-step basis from the Paris law usin g stress intensity factors calculated by the finite element method. Th e crack front is defined by a cubic spline curve from a set of nodes. Both the 1/4-node crack opening displacement and the three-dimensional J-integral (energy release rate) methods are used to calculate the st ress intensity factors. Automatic remeshing of the finite element mode l to a new position which defines the new crack front enables the crac k propagation to be followed. The accuracy and capability of this fini te element simulation technique are demonstrated in this paper by the investigation of various problems of both theoretical and practical in terest. These include the shape growth trend of an embedded initially penny-shaped defect and an embedded initially elliptical defect in an infinite body, the growth of a semi-elliptical surface crack in a fini te thickness plate under tension and bending, the propagation of an in ternal crack in a round bar and the shape change of an external surfac e crack in a pressure vessel.