Stress distribution ahead of an interface crack tip in a ductile adhesive layer

In an adhesive layer sandwiched by stiff substrates, it the plastic zone size r(p) reaches several layer thicknesses ahead of the crack tip, the maximum stress develops around the region of x(1) = r(p), and the stress level is even higher than the one predicted by the remote K-field. The unusual high stress is due to the restraint of the plastic flow by adhesion with the substrates, which is similar to the 'friction hill' occurring in plane strain compression or tension. As a theoretical approach, a slip line field model is proposed, which provides a fairly good approximation of the stress distribution sigma(22)-x(1) within the plastic zone. Using the slip line field approach, a new model is proposed to estimate the plastic zone size.