Expressions governing stress-strain curves in short fibre reinforced polymers

Abstract

The earlier theories of reinforcement for short fibre reinforced composites have been extended to include the estimation of strain as well as stress. Thus the effect on the stress-strain curve of various parameters can be estimated. It is shown that the shape of the stress-strain curve is strongly dependent on the fibre aspect ratio, while being relatively little affected by the adhesion between fibres and matrix. The coefficient of friction has an important effect on the stress-strain curve, and so also does the residual radial stress at the fibre-matrix interface. Unfortunately, little data is available at present on parameters such as friction, adhesion coefficients and residual and Poissons shrinkage stresses. Consequently, we are not yet in a position to design short fibre composites for high strength and modulus, coupled with optimum toughness.