Direct numerical predictions for the elastic and thermoelastic properties of short fibre composites

In this paper we compare the predictions of the thermoelastic properties of misaligned short glass fibre reinforced composites, calculated using the finite-element-based numerical approach of Gusev, with experimental measurements. Characterisation of the microstructure of the two injection moulded materials chosen for examination, in particular the fibre length and fibre orientation distributions, were used to ensure that the computer models were built with the same microstructure as the ‘real’ materials. Agreement between the measurements, in particular for the longitudinal Youngʹs modulus E11 and the longitudinal and transverse thermal expansion coefficients, α1 and α2, and the numerical predictions was found to be excellent. A comparison was also made with the most commonly used micromechanical models available from the literature. The approaches of Tandon and Weng, Takao and Taya and McCullough [Polym Comp 5 (1984) 327; J Comp Mater 21 (1987) 140] were found to give good agreement with both the numerical and measured values, although only the numerical approach showed the same relationship between α1 and the degree of orientation as shown by the real materials.