Mesoscopic Computational Tests for the Identification of Textile Composite Reinforcement Mechanical Behaviour

摘要

Knowledge of the mechanical behaviour of woven composite reinforcements is necessary for simulation of composite performance manufacture. This study aims to recall the specificity of the mechanical behaviour of dry fabrics and to determine these mechanical properties from virtual tests. For this, 3D finite element analyses of unit cells are performed. These computations are not classic computations due to the constitution of the yarns, which are made of thousands of small fibres. The possible motion of the yarn allows changes of undulation, leading to nonlinear biaxial tensile behaviour and renders most of the rigidities, other than tensile stiffness, very weak. The specificities of the calculation in order to reach this mechanical behaviour are described. Several specific aspects of the analysis will be detailed; especially the use of a hypoelastic law based on an objective derivative using the rotation of the fibre which allows a strict evolution of the directions of orthotropy according to the fibre direction. The virtual tests are compared to experimental biaxial tests and shear tests on several reinforcements. Such an approach allows us to understand the phenomena implicated in the behaviour and the main aspects that lead to the specific behaviour of woven media. It can also help in the design of new fabrics by changing some mechanical and geometrical parameters in order to obtain prescribed properties.