Extension-bending coupling phenomena and residual hygrothermal stresses effects on the Energy Release Rate and mode mixity of generally layered laminates

This article presents a novel analytical solution to the delamination problem of interface deformable generally layered (asymmetric and unbalanced) composite laminates. The governing equation describing the interface forces and moments is obtained for the reduced form of the first-order shear deformation theory of plates (FSDT) under plane strain assumptions and accounts for the extension-bending coupling phenomena and residual hygrothermal stresses, both of which have been neglected in the past. The interface forces and moments are included in a novel generalization of the J-integral which is used for the estimation of the Energy Release Rate (ERR). The analytical results of the ERR and the mode mixity exhibit a great agreement with the results of Finite Element (FE) models developed using the Cohesive Zone Method (CZM) and the Virtual Crack Closure Technique (VCCT) for a Double Cantilever Beam (DCB) test of a generally layered fibre metal laminate.

Automated summary

This article presents a new analytical solution to the delamination problem of interface deformable generally layered composite laminates. The governing equation for interface forces and moments is obtained under plane strain assumptions, considering extension-bending coupling phenomena and residual hygrothermal stresses. The interface forces and moments are included in a novel generalization of the J-integral to estimate the Energy Release Rate (ERR). The analytical results of ERR and mode mixity show excellent agreement with Finite Element models for a Double Cantilever Beam test of a generally layered fibre metal laminate, utilizing the Cohesive Zone Method (CZM) and the Virtual Crack Closure Technique (VCCT).