Modelling the formation of new material surfaces during adhesive delamination of a composite

The model of a composite material adhesive delamination is developed. The stress state of an adhesive bound varies to nil, when the bonds with the connected body are broken in the thermodynamic process which represents the delamination. The interaction between the part of the composite including the adhesive layer and the rest of the body is terminated as a result of delamination. We have obtained a system of two variational rate equations of the equilibrium flow of the process to describe the subcritical deformation and delamination. The averaging of the stress-strain state in the adhesive layer allows us to avoid singularity in the dead-end of the formed mathematical cut. The motion along the layer’s bounds of the delamination surface does not lead to singularity uprising. When solving the problem of the subcritical deformation, we have distinguished a small δ-surface on the bound of the adhesive, where the delamination criterion is reached. The load (node forces) distribution on the δ-surface is determined by a repeated solving of the subcritical deformation problem. But the law of motion of the adhesive layer bound at a current stage is known from the initial solution. The problems about simple unloading of the -surface of a body and keeping the external loading value on the level of the delamination start are solved. As a result, the body’s stress strain in the beginning of the local unloading differs from its state, when δ-unloading ends. For the linear elastic problem, we have performed a comparison between the results of the problem solving within the framework of the current model and the results for the model of a cohesive delamination, where a complete destruction of the cohesive layer is assumed. A substantial difference in boundary displacements of main composite layers during the destruction is established after the discontinuity surface’s growth between the adhesive layer and primary material.