Fatigue Crack Growth Prediction in 3D Crack Fronts

G.Cook, P.W.Claydon, C.Timbrell

STRUCENG & FEMCAD Conference, Grenoble, France, 1990

A method is presented for predicting full 3D fatigue crack growth of arbitrary 3D crack fronts under mixed I, II and III mode loading. It uses a generalized 3D virtual crack extension (VCE) method to evaluate the distribution of the local maximum energy release rate, Gmax, along the crack front. A modified Paris equation, relating the local Gmax to the local crack growth rate, is then used to evaluate the magnitude of the crack growth. The direction of local crack growth is taken as the direction of the local Gmax.Good agreement with experimental data is produced for fatigue growth against the number of cycles for an elliptical crack under mode I cyclic loading. Although no experimental results are available, the prediction of full 3D crack growth for a crack front under mixed mode loading is also demonstrated.