Modelling of textile composites with fibre strength variability

Scatter in composite mechanical properties is related to variabilities occurring at different scales. This work attempts to analyse fibre strength variability numerically from micro to macro-scale taking into account the size effect and its transition between scales. Two micro-mechanical models based on the Weibull distribution were used within meso-scale finite element models of fibre bundles which were validated against experimental results. These models were then implemented in a meso-scale model of an AS4 carbon fibre plain weave/vinyl ester textile composite. Monte Carlo simulations showed that fibre strength variability has a limited effect on the strength of the textile composite at the meso-scale and introduces variability of less than 2% from the mean value. Macro-scale strength based on the predicted meso-scale distribution was lower than the strength of the composite without variability by 1-4% depending on the model. The presented multi-scale approach demonstrates that a wide fibre strength distribution leads to a narrow distribution of composite strength and a shift to lower mean values.