A numerical study on the effect of local cohesive property variation to single mode fracture models

In this work, the effect of local cohesive property variation on the fracture behavior of single mode fracture models is numerically investigated. In this context, 3D models for the double cantilever beam test and the end-notched flexure test are built. The bonded interface is considered in two variants: a) homogeneous and b) heterogeneous with a local patch of varying cohesive properties. In order to evaluate the effect of the patch to the fracture behavior, the cumulative damage is introduced as a criterion. Parameters of the patch, i.e. material properties, geometry and position, are varied in a parametric study. Conclusions about their effect on the cumulative damage are drawn and justified. Different conditions of the crack growth are considered, i.e. crack onset and propagation. The results of the study outline the importance of the geometrical design of the patch. Especially the orientation of non-squared patches has a large, disproportional effect on the cumulative damage. Also the fracture mode plays an important role. The obtained information can be used to optimize interlaminar integrated sensors as a mean of structural health monitoring.