Irreversible constitutive law for modeling the delamination process using interfacial surface discontinuities

An irreversible cohesive–decohesive constitutive law is postulated for interfacial surface discontinuities to predict initiation and progression of delamination. An exponential function is used for the constitutive law that naturally satisfies a multi-axial stress criterion for the onset of delamination and a mixed mode fracture criterion for the progression of delamination. The constitutive equations are made thermomechanically consistent by including a damage parameter to prevent the restoration of the previous cohesive state between the interfacial surfaces. To demonstrate the capability to predict delamination and the irreversibility capability of the constitutive law, steady-state delamination growth is simulated for quasi-static loading–unloading cycle of various fracture test specimens. The finite element results are in good agreement with either experimental data available in the literature or with linear elastic fracture mechanics analytical solutions which are valid for sufficiently long cracks.