The influence of single and multiple overloads on fatigue crack propagation

Abstract

The effects of single and multiple overloads on fatigue crack propagation were studied experimentally using the aluminium alloy Al 7475-T7351. The crack propagation stress intensity factor, K PR , was determined after each single and multiple overload sequence. The variation of K PR with the overload parameters can be described by an empirical relationship that unifies the experimental data obtained under a variety of loading conditions. Observations made in the study suggest that load interaction effects are controlled by residual compressive stresses ahead of the crack tip, with fatigue crack closure playing only a secondary role.