Longitudinal failure criterion considering local fiber misplacement for UD composites

Abstract

A new longitudinal failure criterion for unidirectional fibre reinforced (UD) composites is proposed, incorporating the contribution of local fibre misalignment to fibre failure. The failure function was established based on the quadratic polynomial expansion of stress components in the local coordinate system parallel to the misaligned fibres, with coefficients rationally determined based on the basic strength parameters of UD composites. The local stress components were used to determine the failure status associated with fibre compression, while the tensile load along fibres was assumed to have negligible influence on the development of the fibre misalignment. The predicted failure envelopes agreed well with the experimental data for different stress combinations, particularly in the regimes where the fibre failure was influenced by transverse stresses. This validates the predictive ability of the proposed criteria and highlights the importance of the contribution of matrix-failure-related stresses to the fibre-dominated failure behaviour of fibre reinforced composites.