SEDL / STP / STP995V1-EB / STP26786S

Fatigue Crack-Tip Mechanics in 7075-T6 Aluminum Alloy from High-Sensitivity Displacement Field Measurements

Nicoletto, G
Researcher/lecturer, University of,

Pages: 18    Published: Jan 1988

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Abstract

The fatigue crack-tip deformation in the 7075-T6 aluminum alloy has been studied by moiré interferometry, which is a coherent optics technique for full-field in-plane displacement measurements in the submicrometre range. For constant-amplitude-loading conditions the local strain distributions and the crack-tip plasticity have been correlated with theoretical descriptions and models. The effects of a 60% overload on crack propagation has been investigated in terms of flaw profiles and the effective stress-intensity factor. Cyclic plasticity was originally found to depend qualitatively on crack length as much as on the overload-affected growth rate. The implications on crack closure of the moiré results are also discussed.