Multiscale approach to predict the orthotropic elasticity tensor of carbon fibres and woven carbon composites by ultrasonic insonification

Multiscale modeling techniques for composites require input for the mechanical properties of the constituent materials (fibres and matrix). The transverse elastic properties of the fibres are often unknown because no test standard exists to determine them. One can, however, reverse engineer the fibre properties from the 3D homogenized elastic tensor of the unidirectional (UD) material. The full 3D orthotropic elasticity tensor of the UD material (carbon/epoxy) and matrix is obtained through ultrasonic insonificiation. Next, this homogenized elastic tensor is used to reverse engineer the transverse isotropic elastic tensor of the carbon fibres. To this end, 4 homogenization methods are explored: 2 analytical (Mori-Tanaka, Mori-Tanaka-Lielens), 1 semi-empirical (Chamis) and 1 finite-element (FE) (a micro-scale repetitive unit cell) homogenization method. Subsequently, the fibre properties are used to predict the elasticity tensor of UD plies with multiple fibre volume fractions. These are then used for the yarns in a meso-scale FEmodel of a plain woven material. The predicted elastic response is compared to the experimental one. The predicted and measured properties are in good agreement. It is shown that virtual identification and prediction of mechanical properties for woven plies is realistic.