Comparison of finite element predictions of creep crack growth with experimental data

Abstract

Abstract

Five, pre-fatigued, compact tension specimens made from a model material, which exhibits similar macroscopic behaviour to some high temperature materials, have been subjected to steady loads. The results of these tests indicate that the ‘crack tip opening displacement’ governs the intiation of crack propagation. The subsequent creep crack growth rates are accurately predicted by the C∗ parameter.

‘Moving crack’ finite element calculations have shown that accurate predictions of creep crack growth rates are possible even with relatively coarse meshes. However, the predictions are very sensitive to both the critical crack tip opening displacement used for initiation and to the magnitude of the load. Also, although the C∗ parameter is strictly only applicable to stationary state stresses at stationary cracks, predictions of crack growth were found to be accurate when using C∗ under non-stationary stress and moving crack situations.