Simulation of the Thermal Conductivity of Composites

Research project P 14532 Simulation of the Thermal Conductivity of Composites Heinz PETTERMANN 09.10.2000 Within the proposed project simulation and modeling are to be employed to investigate the thermal conductivity of metal matrix composites. Goals are the adaptation of existing as well as the development of new modeling approaches for investigating matrix-inclusion type composites. Special interest is put on orientation distributions of the inclusions of the planar random type in combination with the thermal matrix-inclusion interface properties. Numerical and analytical methods are employed for predictions of the overall thermal conductivity. The analytical approaches are based on Mori-Tanaka type methods which are extended to incorporate the thermal interface behavior. For the numerical simulations unit cell models are employed which are analyzed by the Finite Element Method. Composites with continuous and discontinuous aligned fibers (under consideration of the interface behavior) are investigated first. Then, a methodology for generating generic unit cells with planar random inclusion arrangement with some out of plane deviation is aimed at. Once the generic unit cells for predicting the thermal behavior are available, the transition to modeling the thermo-elastic behavior is relatively straightforward, e.g. for predicting the elastic moduli and the coefficients of thermal expansion. The two different computational approaches and the comparison with experimental results on the thermal conductivity will give a wide picture of the behavior of such materials. It will help to improve the understanding of the physics determining the properties of heterogeneous materials. As an additional part of the proposed project the development of experimental methods for characterizing the interface is supported by computational modeling. The experimental set-ups are analyzed in advance to find appropriate specimen geometries, testing conditions, etc.