The effect of patch geometry on the static and fatigue behaviors of defective aluminum panels repaired with a composite patch

Abstract

In this study, 6.125-mm cracked Al 7075-T6 plates unpatched and repaired with 4-ply boron/epoxy composite patches of several geometries have been investigated under both static and fatigue loads. The stress distributions around the crack tip for these specimens were calculated using the finite element method. It was shown that Rose's model was not adequate to calculate the stress intensity factor for different patch geometries where patch dimensions were on the order of those of the cracked structure. A new definition based on the stress near the crack tip was introduced. Also, based on the experimental data, a new definition for relative repair efficiency was introduced, and the effects of patch geometry on the static tensile and fatigue behaviors of the repaired structures were examined experimentally. Combining the results of static tensile and fatigue tests, it was concluded that the geometry of the patch had large effects on the properties of the repaired structures, the effects not included in Rose's model.