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The initial fracture propagation within a full-scale stiffened quasi-isotropic composite panel and coupons with stringer feet under tensile loads was investigated. The specimens were made from Non-Crimp Fabric through Vacuum assisted Resin Transfer Moulding. The failure loads of all configurations were successfully related using the same value of trans-laminar fracture energy. The method involved independent tests of scaled-down Over-height Compact Tension specimens and the Virtual Crack Closure Technique. It was found to be crucial to include the fully developed damage process zone in the crack length and to interpret the results carefully in order to identify the failure loads consistently. [ABSTRACT FROM AUTHOR]

This paper presents prediction of the high velocity, oblique impact response and quasi-static residual tensile strength of thin [45/90/−45/0] 2s carbon/epoxy laminates using finite element (FE) models. A High-Fidelity Finite Element Method (Hi-FEM) with an automated unit cell meshing technique was employed. The predicted impact damage, characterised by the extent of fibre failure and delamination area, was validated against results from gas-gun tests for a range of impact velocities. The numerical results captured the trend of increasing impact damage with impact energy as observed from the tests. Changes in projectile orientation before impact were shown to increase the extent of fibre failure at high impact energies, up by 38% in edge impact cases. The residual tensile strength of the impacted laminates was then investigated, where the numerical results for edge-impacted laminates agreed with the test data within 8%. On the other hand, the residual strength modelling results of centre-impacted laminates were found to be unconservative, mainly due to the extent of fibre failure predicted during impact. Machined notches were also studied for their residual tensile strength in comparison to impact induced damage. The predicted strength of edge-notched laminates was found to be in close agreement with the experimental results for edge-impacted laminates, differing by an average of 9%. [ABSTRACT FROM AUTHOR]