Crack Propagation Behaviour in Thin Aluminium Alloy Sheet Repaired with Adhesively Bonded CFRP Patch

For reducing the crack tip stress intensity factor, adhesively bonded composite patches are employed for crack repair in thin structure. Experimental work was carried out to study environmental assisted cracking behaviour of crack repaired with single-sided bonded patch in aluminium alloy of 7xxx series in peak-aged condition. The observations were also made on crack in this alloy without any patch repair. The specimen developed for conducting the experiments simulated plane stress condition of thin structure. The patched and un-patched tensile test specimens were loaded simultaneously at constant load in the presence of 3.5% weight NaCl solution. The experimental set-up simulated the saline or corrosive environment. Aggressive effect of corrosion attack on crack due to anodic dissolution along with hydrogen embrittlement leading to faster crack growth in patched specimen was revealed compared to un-patched specimen. The present study is the improvement over similar researches carried out earlier in terms of design of test specimen under plane stress condition so as to obtain all the three regions of crack growth.