Simulating the effect of microstructural inhomogeneity in UD carbon-fibre-reinforced thermoplastics on the mechanical behaviour

Abstract

Calculation and modelling of structures made from continuous fibre-reinforced plastics (FRP) is usually based upon Classical Laminate Theory (CLT), in which inhomogeneous composite plies are considered as homogeneous material. For representing the elastic behaviour of FRPs the CLT-method is well suited. However, plastic deformation and damage behaviour particularly found in FRPs with thermoplastic matrix is affected by inhomogeneities. In this work a detailed analysis of the microstructure of a thermoplastic FRP with unidirectional carbon fibre reinforcement was conducted for generating parametric geometry models representative for different observed microstructures. For calculating the geometry models an algorithm has been developed, which allowed for modifying the fibre diameter distribution and the fibre volume fraction. In finite element simulations the effect of fibre arrangement on the mechanical response in terms of elastic, plastic, and damage behaviour has been investigated. The variation of fibre arrangements resulted in different localized plastic deformations and crack paths and also significant differences in the stress-strain curves. The outlined method of analysing and modelling different relevant microstructures of an FRP provides the basis for more realistic calculations of the mechanical behaviour of FRPs in multiscale models.