In this study, the strength of multi-material structures is predicted by considering deformation and strength degradation in the bonding region. A damage model based on continuum damage mechanics, combined with the finite cover method, is employed to capture crack propagation behavior. First, the formulation of the damage model is presented. This model introduces a scalar damage variable D, which evolves as a function of the damage energy release rate Y. Next, the finite cover method is briefly described. A damage threshold is defined based on the damage variable, corresponding to a specific stress value. The direction of crack propagation is determined using a chosen criterion, such as the maximum principal stress. Several numerical examples are provided to evaluate the proposed methodology. Material parameters for the bonding region are identified using reference experimental data. The crack propagation behavior is also analyzed to assess its impact on structural performance. Crack initiates on the upper side of the specimen and extends toward the opposite side. The force–stroke curve clearly illustrates a reduction in force due to crack growth.
Sugiyama et al. (Wed,) studied this question.