Crack trajectory analysis of single-side repaired thin panels in mixed-mode conditions using glass/epoxy patches

In this paper crack trajectory analyses of the single-side repaired panels in mixed-mode conditions using both experimental and numerical methods are performed. The panels were thin and made of aluminium alloy containing an initial inclined flaw of 45° and repaired with the 4 layers glass/epoxy composite materials. The effects of the patch lay-up configurations on the crack trajectories at patched and un-patched surfaces of the panels are investigated. The experimental results show that the crack trajectories obtained at patched surface are different from those obtained at un-patched surface of the panels and therefore leads to the existence of a three dimensional fatigue-fracture surface for all repaired panels. The performed finite elements results are comparable with those obtained from the experiments. The finite elements results also show that using various patch lay-up configurations may lead to the various crack propagation patches with 5–20% differences at un-patched surface of the panels.