Threshold crack growth and crack closure in ductile iron

This document describes the fatigue threshold crack growth13; behaviour of ferritic ductile iron tested at stress ratios ranging between 0.1 and 0.5 . Automated K-decreasing testing was employed for the determination of threshold stress intensities . Crack closure stress estimates were made based on the P-COD curves obtained during testing . Based on this study, it was inferred that the threshold crack growth in this material is not strongly influenced by the applied stress ratio ; crack closure could explain the stress ratio effect