Deducing the R-curve for trans-laminar fracture from a virtual Over-height Compact Tension (OCT) test

The R-curve for Mode I trans-laminar fracture energy in quasi-isotropic IM7/8552 carbon/epoxy laminates is here deduced numerically from a virtual Over-height Compact Tension (OCT) test. A High-fidelity Finite Element Method (Hi-FEM) using the explicit Finite Element (FE) software LS-Dyna was adopted. Cohesive interface elements and a Weibull fibre failure criterion were used to predict failure. The input parameters for the Hi-FEM were measured from independent characterisation tests. OCT specimens were tested to verify the Hi-FEM results with good agreement. The R-curve effect is postulated to be caused by the growth of the height of the Fracture Process Zone (FPZ) with crack length. Hi-FEM can be used to better understand Mode I trans-laminar fracture toughness tests and generate fracture properties such as damage heights and R-curves for future structural scale models.