Behavior of a flat internal delamination within a fiber reinforced cross-ply composite

Abstract

A penny-shaped delamination is modeled as a flat octahedral shaped crack between layers of a cross-ply laminate. The fibers of the laminate intersect the edges of the delamination at angles of 0 • /90 • , +45 • /−45 • , 90 • /0 • and −45 • /+45 • as one proceeds along the delamination edge. Two lay-ups are considered, a cross-ply consisting of two layers, and a symmetric composite, consisting of three layers. The delamination is always between two of the layers. Both tension and shear are applied to the outer boundary of the body. Stress intensity factors about the delamination edge are calculated by means of a conservative M-integral. These are employed to calculate the interface energy release rate and corresponding phase angles. Use is made of existing experimental results to predict the location of propagation along the edge of the delamination. It was found that the most dangerous regions along the delamination front occurred for the 0 • /90 • or 90 • /0 • interfaces.

Fracture Mechanics Analyses for Interface Crack Problems - A Review

“…specifically for a 0°/90° interface [74]. The parameters H 1 and H 2 are functions of the material properties.…”

“…It should be noted that the phase angle ψ depends on an arbitrary length parameter L while φ is length independent. The criterion used by Banks-Sills et al [74] is based on the energy release rate given by…”

“…Details are given in reference [69]. Application examples for an embedded delamination in a cross-ply composite and through the width delaminations are presented in references [74,75]. The validity of the method for general laminates is yet to be established.…”