Repair strength predictions of cracked metal plates bonded with composite patches using elastic-plastic finite element method

The structure strength of cracked metal plates can be greatly improved with the help of bonded composite patches. However, the existence of crack in cracked plates will lead to serious stress concentration phenomenon and produce plastic deformation easily, which shows strong material physics nonlinear characteristics. It is necessary to use elastic and plastic mechanical principle to predict the static strength of the repaired structure bonded with composite patches. Considering the material nonlinearities of the metal plate materials, the elastic-plastic finite element model of the cracked metal plates bonded with composite patches was established, which was validated by test results. On the basis, a method predicting tensile strength was proposed based on crack opening displacement (COD) theory in crack tip, and the plastic deformation, COD of the repaired structure and static tensile strength were analyzed. Results show that, compared with the stress intensity factor K theory, the COD theory can give more precise result in predicting the static tensile strength of the repaired specimen.