An experimental study was performed to investigate the effect of single overload on fatigue crack propagation of side-grooved CCT specimen and surface crack specimen. The specimen made of Aluminum alloy 7075-T6.
Result showed that the retardation of crack propagation rate under the single overload can not be explained by the crack closure only. Delayed retardation and retardation exist more widely in the crack length direction of surface crack which is in the plane stress state than the crack depth direction and side-grooved CCT specimen which is in the plane strain state. After single overload, crack growth behavior of depth direction for surface crack specimen is similar to that of side-grooved CCT specimen. And after the influence of single overload, aspect ratios of surface crack are being equal to the constant amplitude test.
