Finite element analysis of mechanical properties of woven composites through a micromechanics model

Abstract

In a woven fabric composite, arrangement and behavior of the fibers contained in the yarn and the yarns themselves lead to an intricate deformation mechanism. The current research, therefore, intends to propose a simplified mathematical micromechanics model for calculating mechanical properties of the plain weave composite using finite element analysis (FEA). A repetitive volume element (RVE) cell approach has been adopted for properties evaluation of plain weave composites. The FEA allows the modeling and portrayal of fabrics by taking into account various geometric parameters such as the yarn undulation, the probability of existence of consonances in a unit cell and interaction between warp and fill tows. These factors help in generating a mesh close to the actual fabric/composite. Additionally, a technique to represent the internal layout of composite structure employing actual dimensions of yarn geometry using conventional measurement devices, rather than using the demanding method of obtaining measurements from photomicrographs of sectioned laminates, is also proposed. The geometric symmetries as reported in the available literature were also incorporated during the model formulation. The theory of comparative displacements was then used to construe these symmetries into appropriate mechanical terms. Consequently, this leads to the formulation of boundary conditions for the RVE. The proposed finite element micromechanics model is different from the existing models in a way that it defines the yarn cross-sectional path based upon computational fluid dynamics technique rather than conventionally obtained photomicrographic results or the proposed sinusoidal paths by various researchers. Experiments were then performed on the laminates used for obtaining the geometric parameters with the aim of supporting the validity of the suggested model. The results of computational analysis were found to be in good agreement with the outcomes of experimental investigation.