Use of Composite Patches As Reinforcements and Crack Arrestors in Aircraft Structures

The application of adhesively bonded composite patches as reinforcements and crack arrestors is considered. The bonded composite patch was tested as reinforcement to prevent cracks from coalescing. With a finite element model developed for composite patch repairs, the effect of thermal residual stresses on crack growth rate was demonstrated. The thermal stresses were quantified by comparing the experimental results with the model predictions. Reinforcement for a multiple site damage situation was analyzed by modeling an infinite row of closely spaced cracked rivet holes. The composite reinforcement was shown to dramatically reduce stress intensities, increase fatigue life, and protect against catastrophic failure.