Influence of non-uniformity in inter-fibre distance on strength distribution of unidirectional fibre-reinforced polymer composites

Abstract

Unidirectional fibre-reinforced polymer (UDFRP) composites exhibit statistical variations in the material properties. It is essential to acknowledge these variations and use a statistics-based strength property for designing composite structures. In this work, the effect of non-uniformity in inter-fibre distance on the statistics of strength distribution of UDFRP composite is studied through computational micromechanics. Micromechanics-based realisations of the UDFRP composite are developed with a quantified measure of non-uniformity (MoN) in fibre distribution through an algorithm. Several realisations of these models are created for each non-uniform fibre distribution. External stress is applied to each realisation in the transverse direction till failure initiates in the matrix. The modified Drucker–Prager failure criteria are implemented for matrix failure. This externally applied stress is termed as the failure initiation strength. Statistical distribution of failure initiation strength is obtained for each fibre distribution. Variations of mean value, standard deviation and B-basis of failure initiation strength with the measure of non-uniformity in fibre distribution are studied for the fibre volume fractions of 0.5 and 0.6. In addition to the mean value, non-uniformity in fibre distribution also significantly influences the standard deviation and B-basis of strength distribution.