A Plate Finite Element for Modeling Delaminations

Laminate constitutive relations are derived for a composite plate, the midplane of which is offset from the reference x-y plane. The equations are similar to the conventional laminates except that the definition of the [ A], [ B], and [ D] matrices are dif ferent. This offsetting procedure is convenient for finite element modeling of delamina tions. Starting with the three-dimensional J-integral, an expression for strain energy release rate for delaminations is derived. Unlike the crack closure method, the G can be derived with one single computation; further, the distribution of G along the delamination front can also be obtained. The method is illustrated for an anisotropic DCB specimen.