Finite Element Implementation of Fibre-Reinforced Materials Model in Abaqus/Explicit

Abstract

This thesis is concerned with the constitutive modelling of short fibre-reinforced composites in the finite element code Abaqus/Explicit. The model is presented as a generic framework which is based on a two-phase representation of the composite material. The fibres and matrix define the two phases. The fibre phase is characterised by its volume fraction and a discrete representation of the orientation distribution where each discrete representative is modelled with a simple one-dimensional elastic constitutive relation. The matrix phase is modelled with a pressure sensitive elastic-plastic mechanical behaviour, but the generic framework allows for the easy implementation of other constitutive relations as well. The contributions from both phases are scaled based on their respective volume fractions and added together to form a tangible stress state.

The model is then implemented in FORTRAN. The implementation is verified through a series of comparisons to other existing models and solutions. The verification process yielded reasonable results and the model is assumed to be working according to the established foundation.

Experimental data from uniaxial tensile tests of fibre-reinforced polypropylene retrieved from a literature source were used in the validation of the model. The validation process disclosed the potency of the model, but also some shortcomings. Finally, concrete suggestions for improving the model are presented.