The fatigue repairing evaluation of hybrid woven composite patch with 2D&3D styles bonded Al-alloy plates under UV and thermal curing

摘要

The fatigue performance of repaired Al-alloy plates bonded by 2D&3D woven composite patch under UV and thermal curing was evaluated. The fatigue life N, crack growth rate da/dN, stress intensity factor range Delta K, the 'm' from Pairs equation and the fracture morphology were characterized to investigate the influence of patch styles and curing methods on the repairing effect. The results showed that fatigue performance was enhanced relative to unrepaired system. The stress was transferred from the crack tip to composite patch by adhesive for reducing the Delta K, and then da/dN was further restrained, contributing to the improvement of fatigue lifetime. The 3D patch had better repair effect than that of 2D patch, and UV curing was superior to thermal curing. It was more sensitive to the curing methods. The sample repaired by 3D patch under UV radiation (U-3D/25) presented the optimal performance, and fatigue lifetime reached 48651 cycles, increased by 806.14% relative to unrepaired system, which was proved by the decrease of 'm'. The repair samples showed different fracture morphologies, which was attributed to changes of crack propagation path and stress distribution of different repair system. The fracture surface of U-3D/25 revealed ductile fracture features, presenting the optimal repair effect.