MODELING FATIGUE CRACK-GROWTH AND COALESCENCE IN NOTCHES

An experimental and analytical study of the process of fatigue crack growth and coalescence in the region of a notch has been performed. The experimental program consisted of constant amplitude fatigue tests of 24 V-notched steel bar specimens, 11 of which had two starter cracks designed to simulate crack coalescence. The results of the experimental program are presented and compared to computer predictions of fatigue crack growth. These were produced by software that performs an integration of the Paris crack growth law and incorporates a new crack shape development and crack coalescence model. It has been found in the present study that pre-coalescence interaction between adjacent cracks is not evident and, in fact, that coalescence itself is not an instantaneous process. This result is of interest because it is at variance with the existing design codes that deal with the case of adjacent collinear fatigue cracks.