Multi-scale 3D image-based modelling of a carbon/carbon composite

Detailed thermal and mechanical finite element analyses of woven composites are computationally challenging due to the heterogeneous nature and the geometrical complexity of the composite. In this paper two finite element three-dimensional image-based models at different length scales are used to evaluate the thermal diffusivity and stiffness of a 2D carbon/carbon composite. The micro-scale model was developed from SEM micrographs of the carbon tow whereas the macro-scale model was derived from high resolution x-ray tomographic images of the composite. The micro-scale model predicts thermal conductivities and Young's modulus at the tow scale in the three orthogonal directions (x, y and z). The output results from the micro-scale model are then incorporated in the macro-scale model to obtain through-thickness thermal diffusivity and in-plane Young's modulus. The modelling results are in excellent agreement with the experimental results obtained from the laser flash and tensile tests and the deviations are within the bounds of numerical error of 5%. (paper)