PREDICTING FATIGUE LIFE IN COMMERCIALLY PURE ALUMINUM USING A SHORT CRACK-GROWTH MODEL

Advances in manufacturing techniques and improvements in non-destructi ve inspection procedures have reduced the size of initial defects in f atigue-critical components to the scale of the microstructure. Unfortu nately, the growth of these so-called short fatigue cracks is not prop erly characterised by conventional linear elastic or elastic-plastic f racture mechanics. However, the Navarro-de los Rios crack growth model does account for many aspects of their growth and has proved successf ul in predicting fatigue life of medium carbon and C-Mn steels. In con sequence, the growth of short fatigue cracks in commercially pure alum inium, under fully reversed uniaxial loading, has been studied, using a plastic replication technique and modelled, using the Navarro-de los Rios crack growth equation. The predicted lifetimes are in good agree ment with the actual experimental lifetimes, and compare favourably wi th predictions based on two previously reported crack growth models.