Parametric study of a 3D composite structure

Jiri Had, Milan Ružička

Abstract


The goal of this study is to determine and verify the stiffness properties of a novel type of 3D composite. The 3D composite is created by a moulding process of sub-cells. These sub-cells are based on uni-directional composite fiber tows which are over-wound at certain angles by thin composite layers. The advantage of the 3D composite is its much higher shear strength and stiffness in comparison with thick unidirectional composite parts. These 3D composite parts are primarily used in complex thick-walled composite structures, for example in aircraft spars or in machine tool applications. The purpose of the thin over-winding of the cells is not only to create the shape of the cells during processing but also to provide a structure across the cross-section of a structural part. The over-winding of the cell contributes to the high stiffness properties of the whole structural part.
The linear Hooke’s model for an orthotropic material is considered for an approximation of the material. The simple mixture rule is used to determine the stiffness of the cores and the over-winding. The volume ratio of the fibre in the cells and in the over-winding is obtained from observation in a scanning electron microscope (SEM). Various types of carbon fibres such as high strength or high modulus fibres are integrated into a 3D composite.
A final stiffness property of the whole 3D composite is obtained in an averaging process based on a homogenization technique implemented in FEA. A complex parametric 3D FE model was performed using periodic boundary conditions. The technology parameters that were investigated in the FEA were: angle of over-winding, thickness of the winding and radius of the corners between the cells, etc.

Keywords


Structural composites, Finite element analysis (FEA), Elastic properties, Hybrid composites, Mechanical properties

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ISSN 1801-1217 (Print)
ISSN 1805-9422 (Online)
Published by the Czech Technical University in Prague, Faculty of Mechanical Engineering