AN ANALYSIS OF THE GROWTH OF SMALL FATIGUE CRACKS

The straightforward use of linear elastic fracture mechanics (LEFM) is known to be invalid in the small crack regime. However, as demonstrated in the present paper, the range of validity of the LEFM approach can be extended into this range by introducing modifications to deal with the large plastic zone size to crack length ratio and by introducing a material constant which provides for a smooth transition between the endurance limit and the threshold level for fatigue crack propagation. In addition, the influence of crack closure and its development must also be considered. Examples are given to demonstrate the application of the proposed method.