Equivalent Crack Size Modelling of Corrosion Pitting in an AA7050-T7451 Aluminium Alloy and its Implications for Aircraft Structural Integrity.

摘要

Ageing military aircraft fleets are becoming the norm as fleet managers try to extend operational life without compromising safety. This has led to substantial world-wide research into ageing aircraft and the implications of corrosion and multi-site damage on aircraft residual strength and fatigue life. This report details part of DSTO's research program into the effect of pitting corrosion on aircraft structural integrity. The report focuses on F/A-18 structural aluminium alloy and its susceptibility to developing large pits. The report emphasises that with the present design philosophies of Safe-Life and Damage Tolerance, the major corrosion problem areas on aircraft will be secondary structure or non-fracture critical structure. The report also shows the applicability of the Equivalent Crack Size approach to assessing corrosion. While the ECS approach needs further research, it appears to be, currently, the best approach to assessing pitting corrosion and its effect on aircraft structural integrity.