Delamination of Bonded Repairs
A Damage Tolerance Approach
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Abstract
A model was developed for delamination growth in bonded repair patches under constant amplitude fatigue loading. The model used the finite element method, employing the virtual crack closure technique, to determine the strain energy release rate (SERR) as a function of delamination length. Interaction effects between multiple delaminations, and the effect of delamination shape was also investigated. Fatigue cycling of coupon specimens was performed in order to find a relation between the SERR and the delamination growth rate. A power law (Paris-type) relation was established. Using this relation and the relation between SERR and delamination length, delamination growth predictions were produced. This predictions agreed well with the results of the coupon tests. A further validation by tests on more representative patch repair specimens was inconclusive due to the lack of delamination growth in the patch repair specimens.