INTERFACE CRACK OR DELAMINATION: WHEN & WHERE TO INITIATE? HOW TO PROPAGATE & HOW BIG AREA TO ATTAIN?

After inserting a matrix, secondary layer in between the two adjacent primary layers of the bimaterial, the overall load causing the weakest secondary layer element to fail can be even bigger than the bimaterial’s strength. The stresses in the element must be untrue. In this paper, two modifying coefficients (MCs) are applied to modify the stresses, which are then substituted into a strength failure equation of the matrix. If it is fulfilled, the failed secondary layer element is deleted, and an interface crack occurs within the two adjacent primary layer elements. Continued in this way step by step, all of the interface failure information is available without iteration. Only the critical displacements at the peak loads of a DCB (double cantilever beam) and an ENF (end notched fracture) tests are required as inputs in addition to the material properties of the two primary layers and the secondary layer.
EXTENDED ABSTRACT