Effect of pre-corrosion on the MSD occurrence probability

Aimed at the multiple side damage (MSD) existed in the typical aircraft structural components, the occurrence probability of multiple side damage was investigated. The condition of pre-corrosion was dipping in 3.5%NaCl solution for 240 hours. The influence coefficient C was obtained based on the pre-corrosion and the normal fatigue experiment of 7B04-T74 aluminum alloy single detail specimens. The relationship could be established between the MSD occurrence probability under the specified pre-corrosion and the MSD occurrence probability under the normal fatigue condition. The formula of MSD occurrence probability after per-corrosion was gained. The calculation and experimentation results were compared. Results show that the new formula can compute the MSD occurrence probability after pre-corrosion commendably.