Crack initiation and growth in brittle bonds

A fracture mechanics based analysis of the strength of a bond between a thin plate and a substrate is presented. The bond edge is regarded as a crack front, which is loaded under combined mode I, II and III conditions. A numerical procedure is used to study crack initiation and growth. Results for bond strength are presented and effects of free plate edges and closely spaced bonds are studied. Crack growth at the interface is simulated by assuming a growth rate criterion, which is verified by ensuring that the fracture criterion is satisfied locally along the growing front. Experimental results are obtained and show good qualitative agreement with predictions.