Should the translaminar fracture toughness of laminated composites be represented by the [formula omitted] or the [formula omitted] curve? A comparison of their consistency and predictive capability

Abstract

The translaminar fracture toughness of laminated composites can be determined experimentally assuming either linear elastic fracture mechanics (LEFM) or cohesive zone model (CZM) hypotheses. Each theoretical frame is different in terms of complexity and predictive capabilities. To clarify the latter point, we derived the R(Δa) (LEFM) and J(ω) (CZM) curves from a set of published results on over-height compact tension fracture specimens of different sizes. Then, these curves were used to predict the strength of other coupons of the same material (geometrically similar, scaled, open hole and center cracked specimens). Since the idealization of the fracture phenomena in cohesive zone models is more realistic than in LEFM, the fracture property so obtained is more independent from the size of the specimen used to measure it and its predictive capability embraces a wider range of sizes and geometries.