Prediction of shape change of semi-elliptical surface crack by fatigue crack growth circles parameter

摘要

As a fatigue crack grows, its shape changes. The shape of the growing crack can be affected by the initial crack shape, the load type and the fatigue crack growth rate of the material. Existing methods to predict the shape of the growing crack include finite element simulation techniques, which typically require the computation of several hundred increments to get accurate results. This paper describes a new technique that uses growth circles to model the growing crack. Since the circles are perpendicular to the current crack front as well as to the new crack front, it represents the real path of the fatigue crack well and yields more accurate results. The new technique is to be applied to the case of a surface crack in a thick plate under tension or bending. The effects of the Paris-Erdogan exponent are also investigated.