RVE modelling of short fiber reinforced thermoplastics with discrete fiber orientation and fiber length distribution

Abstract

This study presents an analysis of modelling aspects on the effective composite properties of short glass fiber reinforced thermoplastics using representative volume elements (RVE). Although, many investigations were published showing effects of different modelling parameters of RVEs, we further elaborate in this contribution the parameters: influence of fiber packing, fiber shape, bonding of the fibers to the matrix, fiber length distribution and fiber orientation. The knowledge of these influences is used to determine the extent to which the increased modelling accuracy and thus the computational effort leads to an improved RVE's forecast quality. This objective is achieved by creating and comparing different RVE models of a PBT-GF20 composite. The information required for the RVE models is obtained by experimental characterization of the PBT-GF20 and the PBT matrix material. It can be concluded based on the results of the numerical investigations in conjunction with the experimental tests of the composite that fiber packing, fiber length distribution, fiber orientation and fiber geometry are essential for a precise determination of the effective composite properties.

A Study to Derive Equivalent Mechanical Properties of Porous Materials with Orthotropic Elasticity

“…Homogenization methods include the representative unit cell method [15] and the representative equivalent continuum method [16], but the most dominant homogenization method is the representative volume element (RVE) method [9][10][11][12]. The representative volume element method is applied to estimate the stiffness of fiber composites [9] or to estimate the equivalent properties of reinforced plastics mixed with multidirectional fibers [10]. It has also been used in studies to estimate the equivalent properties of an anisotropic material [11,12].…”

“…When various materials or pores are distributed within a unit volume, it is assumed that all material properties within a unit volume are the same (Figure 1). The related governing equations are shown as Equations ( 1)-( 5) below [9][10][11][12]. Equation (1) means that the strain energy before and after homogenization is the same.…”

“…This may distort the results of the finite element method, and is a limitation when using the finite element method for the materials. To solve this problem, a method is used to estimate and utilize equivalent mechanical properties while simplifying modeling by applying the homogenization method for composite materials [9][10][11][12].…”

Modelling and Experimental Investigation of Hexagonal Nacre-Like Structure Stiffness

“…It is important to note that a nacre RVE is not symmetric but only periodic, which makes some analytical models not suitable for a hexagonal-based tablet when compared to simplified rectangular tablets with half-length overlap. Periodic models such as RVE have been previously shown to more accurately estimate the composite structure stiffness than analytical models if they are correctly modeled [51]. This RVE of nacre is the minimum required volume to represent the composite, as the structure is periodic and very ordered, with known reinforcement dimensions and orientation governed by the lamination assembly process.…”

Modelling the Effect of Fibre Length Distributions in Short Fibre Reinforced Composites

“…Both the FLD and the FOD vary locally in an injection moulded part [1]. For a reliable prediction of the material behaviour, these parameters need to be represented adequately in a micro-mechanical model [2]. In this work, the two-step Orientation Averaging (OA) model for SFRCs, developed by Mirkhalaf et al [3], is extended to consider also FLD for linear elastic and non-linear elasto-plastic behaviour of SFRCs.…”