Constitutive modelling of impregnated continuous fibre reinforced composites Micromechanical approach

Abstract

This work is aimed at understanding and modelling the draping of engineered prepregs and reinforced thermoplastics through the development of constitutive models for use in numerical draping codes. Results from picture frame tests are presented, which indicate the behavioural response of these materials to shear deformation, when varying parameters such as temperature and shear rate. Observations are then presented illustrating how intraply shear deformation can be either heterogeneous or homogeneous on a mesoscopic scale, depending on the test's boundary conditions. Two distinct modes of deformation are identified and explained by consideration of simple shear kinematics within the ply. The mode of deformation is shown to influence dramatically the velocity field between crossovers in woven fabrics and a qualitative argument is presented to suggest that the contribution to the total deformation energy from crossovers is negligible. Implications of these different modes of deformation on the forming of three-dimensional components are analysed.