Application of the Hartman–Schijve equation to represent Mode I and Mode II fatigue delamination growth in composites

This paper discusses the potential of a variant of the Hartman–Schijve equation to represent both Modes I and II constant amplitude delamination growth in composites. To this end we show that the delamination growth rate da/dN can often be related to (Δ√G − Δ√Gth)α, where α is approximately 2. As such the exponent in this relationship is considerably lower than the exponent in “Paris like” power law representations. We also show that this particular representation of delamination growth in composites is similar to that seen for crack growth in metals.