Stepped and optimised overlap wet lay-up patch repairs for aerospace composite structures

This study assessed stepped and overlap wet lay-up composite patch repair methods. The stepped repair design exhibits many desirable features such as high strength recovery and flush installation, however typically results in excessively large repair sizes, making them unsuitable for many repair areas. Furthermore, stepped repair application requires removal of large areas of pristine composite material and is thus time and resource intensive. In this work, a coupon mechanical testing program and a simple constrained, discrete optimisation approach demonstrates that the use of an optimally designed overlap patch repair can provide equivalent mechanical performance, but with reduced patch size, repair application time and repair complexity. This optimised repair design also significantly improves future part repairability through preservation of pristine structure.