DELAMINATION CRACKS ORIGINATING FROM TRANSVERSE CRACKING IN CROSS-PLYLAMINATES UNDER VARIOUS LOADINGS

Delamination cracks originating from transverse cracking in two types of cross-ply laminates [90/0]s and [0/90]s are analysed for three type s of loadings: plane strain extension, plane strain bending and antipl ane shear. The asymptotic solution for stress and displacement field i s constructed based upon the Stroh formalism for anisotropic elasticit y and the method of eigenfunction expansion. Its structure is determin ed from appropriate near-field conditions leading to the eigenvalue eq uation, and then the singular hybrid finite element method in conjunct ion with a quadratic programming procedure for treating the partial co ntact of crack faces is employed to complete the field solution. The s tress intensity factor properly defined for anisotropic interfacial cr acks and the energy release rate are computed from the complete soluti on. The stability of crack growth and the effect of the relative ply t hickness upon the crack growth stability are examined in terms of the energy release rate and the phase angle.