Two-dimensional microstructure based modelling of Young's modulus of long fibre thermoplastic composite

Abstract

The dependence of physical and mechanical properties on microstructure is well known. Various numerical and analytical methods are routinely employed to predict the properties of multiphase materials but these models make certain simplifying assumptions about the microstructure of the material, such as homogeneity, that are not accurate. In the present work, a microstructure based finite element code called object oriented finite element method (OOF) has been used to investigate the longitudinal elastic modulus of a long fibre reinforced thermoplastic (LFT) composite (glass fibre/polypropylene). The modulus value predicted by OOF was then compared with the experimental value and values predicted by various models. It is shown that by taking into account the important microstructural parameters in the composite, i.e. the actual fibre orientation and distribution, accurate prediction of modulus can be obtained. List of symbolsd fibre diameter E cl longitudinal composite modulus E f fibre modulus E m matrix modulus G m shear modulus of the matrix , c critical fibre length r fibre radius R mean spacing of the fibres V f fibre volume fraction V m matrix volume fraction X i factor defining geometric packing arrangement of the fibres b shear lag parameter g , fibre length-efficiency factor g o Krenchel orientation factor j empirical factor s max fibre fracture strength t i shear strength of the fibre/matrix interface w max maximum packing fraction of the reinforcement w n fibre angle with respect to applied load Y function of the fibre volume fraction and w max