The Energy Release Rate in the General Delamination Problem of Anisotropic Laminates Under Thermomechanical Loads

A simple formulation, directly in terms of the local variables of the laminated plate theory, is used to derive the general expression of the energy release rate at a boundary point of an arbitrarily shaped delamination in a multilayered anisotropic laminate under combined mechanical and temperature loads. The intact and de-bonded sublaminates are modeled using the first-order shear deformation theory. If the thermoelastic constitutive equations of the sublaminates are linear and uncoupled, then the expression of the energy release rate may be reduced to a simple form depending only on the sublaminate stiffness coefficients and the local values of the midplane strains and curvatures. The expression does not explicitly involve the temperature load, and is also independent of the strain and curvature parameters tangential to the delamination front. The corresponding expression for delamination in classical laminated plates is also given. The results are applied to the problem of a laminated strip with a fully developed edge delamination loaded under axial extension, bending, and twisting.