Corrosion behaviour of stop-hole and notch instead of crack in thin aluminium alloy sheet repaired with bonded patch exposed to saline environment under constant load

• Published in: Engineering failure analysis 2021-02, Vol.120, p.105067, Article 105067
• Main Authors: Bakare, A.K., Shaikh, A.A., Kale, S.S.
• Format: Article
• Language: English
• Subjects: Aluminium alloy7xxx series; CFRP Composite patch; Corrosion Behaviour; Crack and Notch; Environmental Assisted Cracking; SEM Fractography
• ISSN: 1350-6307; 1873-1961
• DOI: 10.1016/j.engfailanal.2020.105067

•Defects repaired by Asymmetric composite patch in thin aluminium structure.•Detrimental effect on crack propagation rate when exposed to saline environment.•Severe Anodic Dissolution and Hydrogen Embrittlement in the crack region.•When crack replaced with notch or stop-hole, no Hydrolysis of electrolyte at the tips.•Initiations of cracks from Notch or Stop-holes regions have not been noticed.•SEM fractography distinctly reveals this phenomenon in notch and stop-hole specimen. For a crack in thin structure, bonded composite patches are proven successfully in reducing the Stress Intensity Factor (SIF) and enhancing the fatigue life. They are also proven for reducing the Stress Concentration Factor (SCF) when such patches are employed on a thin structure containing drilled holes or notches. It is the established fact that application of composite patches for crack repair is to enhance structural integrity, however on the other hand it had shown detrimental corrosion behaviour at the crack tips under saline environment with application of constant load. It is now needed to circumvent the unfavourable corrosion effect on crack repaired with Carbon Fibre Reinforced Plastic (CFRP) patch. In the current research work the experimental investigation was continued with stop-holes and notch instead of crack tips by drilling stop-holes or creating notches. The favourable results have been obtained by replacing crack tips with stop-holes and notches. The physical phenomenon on corrosion behaviour of stop-hole and notch tips with respect to a general crack repaired with bonded patch is commented in the current research. The experimental investigation is validated with Scanning Electron Microscope (SEM) fractography.