Analytical determination of the modes I, II and III energy release rates in a delaminated laminate and validation of a delamination criterion

The aim of this paper is the analytical determination of the strain energy release rates in a delaminated laminate by means of a model of plates which provides no singular stresses. The strain energy release rates are expressed as quadratic functions of the interfacial stresses at the crack tip. These expressions and relevant delamination criteria can help predict delamination onset and growth. As an application example, data from edge delamination tests on carbon-epoxy laminates are used for determining a mode III delamination criterion involving the corresponding energy release rate. This criterion yields very accurate predictions and its analytical expression validates from an energy point of view a maximum stress criterion proposed in an earlier paper.