Deformation, yield and fracture of unidirectional composites in transverse loading - 1. Influence of fibre volume fraction and test-temperature

The influence of the fibre volume fraction and test-temperature on the transverse tensile properties of glass fibre reinforced epoxy is studied using experimental and numerical techniques. The numerical analyses are based on micromechanical models with square and hexagonal fibre packings. Special attention has been directed towards the identification of the necessary failure criteria. Using a von Mises failure criterion, an increase in transverse tensile strength is predicted at higher fibre volume fractions with both models. This is in good quantitative agreement with experimentally determined transverse flexural strengths. With decreasing test-temperatures, higher transverse strengths are obtained. This is primarily caused by the temperature dependence of the yield stress of the matrix. The counteracting influence of the residual thermal stresses and the temperature dependent matrix ductility consequently proved to be less significant for the transverse strength. (C) 1999 Published by Elsevier Science Ltd. All rights reserved.