Evaluation of homogenized thermal conductivities of imperfect carbon-carbon textile composites using the Mori-Tanaka method

摘要

Three-scale homogenization procedure is proposed in this paper to provideestimates of the effective thermal conductivities of porous carbon-carbontextile composites. On each scale - the level of fiber tow (micro-scale), thelevel of yarns (meso-scale) and the level of laminate (macro-scale) - a twostep homogenization procedure based on the Mori-Tanaka averaging scheme isadopted. This involves evaluation of the effective properties first in theabsence of pores. In the next step, an ellipsoidal pore is introduced into anew, generally orthotropic, matrix to make provision for the presence of crimpvoids and transverse and delamination cracks resulting from the thermaltransformation of a polymeric precursor into the carbon matrix. Other sourcesof imperfections also attributed to the manufacturing processes, includingnon-uniform texture of the reinforcements, are taken into consideration throughthe histograms of inclination angles measured along the fiber tow path togetherwith a particular shape of the equivalent ellipsoidal inclusion. The analysisshows that a reasonable agreement of the numerical predictions withexperimental measurements can be achieved.