THE PREDICTION OF MATRIX CRACKS IN CROSS-PLY LAMINATES

The concept of energy release rate and the analysis method developed by A.S.D.Wang in the case of transverse cracks are used to predict three types of matrix cracking in crossply laminate family at the late stage of uniaxial tensile loading.Cracking events analysed include longitudinal splitting in 0°-ply,0/90° interface localized delamination emanating from the intersection of the transverse crack and the coupon free edge,and similar delamination around the cross point of the transverse and longitudinal splitting cracks.A 3-D finite element analysis is performed to simulate those clack development procedures and the corresponding energy release rate curves,as functions of crack size a,are obtained on the basis of Irwin's crack closure tech nique.After determining the effective inherent flaw sites,the values of critical loading for considered cracking are then pridicted and found to agree well with the experimental results.