A new model based on finite fracture mechanics is proposed to predict the openhole tensile strength of composite laminates. Failure is predicted when both stressbased and energy-based criteria are satisfied. The material properties required by the model are the laminate unnotched strength and fracture toughness. No empirical adjusting parameters are required. Using experimental data obtained in quasiisotropic carbon-epoxy laminates it is concluded that the model predictions are very accurate, resulting in improvements over the traditional strength prediction methods. It also is shown that the proposed finite fracture mechanics model can be used

A micro-mechanical finite element model of a composite sublaminate is proposed to study the mechanical response of ultra-thin plies, consisting of a representative volume element of a 90 • thin lamina in-between two homogenised ±θ • plies. Random fibre distributions, materially and statistically equivalent

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Please cite this article as: Arteiro, A., Catalanotti, G., Melro, A.R., Linde, P., Camanho, P.P., Micro-mechanical analysis of the effect of ply thickness on the transverse compressive strength of polymer composites, Composites: Part A (2015), doi: http://dx. AbstractA micro-mechanical model is used to study the effect of ply thickness on constrained 90 • plies subjected to transverse compressive loading (in situ effect). For cross-ply sublaminates with conventional, standard-thickness 90 • plies, failure is dominated by fibre-matrix interface cracking and large localised plastic deformation of the matrix, forming a localised band in a plane that is not aligned with the loading direction. Ultra-thin plies show a dispersed damage mechanism, combining wedge cracking with ply fragmentation/separation. Moreover, a transverse crack suppression effect is clearly observed. To the authors' knowledge, it is the first time an in situ effect in transverse compression has been identified. When comparing the results of the micro-mechanical model with the predictions from analytical models for the in situ effect, the same trends are obtained. These results also show that, for realistic ply thicknesses, these analytical models can be considered fairly accurate.

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