Numerical analysis of the coupling between mechanical strain and thermal conductivity of ceramic matrix composites

The paper addresses the numerical modeling of the coupling between mechanical strain and thermal conductivity in Ceramic Matrix Composites {CMCs} when subjected to uni-axial mechanical straining. A computationally economic finite element-based multi-linear elastic orthotropic mechanical materials description combined with a multi-linear discretisation of thermal conductivity-strain response has been developed to predict the stress-strain, fracture, and thermal conductivity-strain behaviour of a ceramic matrix composites with strain-induced damage. The finite element analysis utilises a solid element to represent an homogenised orthotropic medium of a heterogeneous uni-directional tow. The discretised non-linear multiaxial stress-strain curves and non-linear multi-axial strain dependent thermal behaviour have been implemented by a user defined subroutine in the commercial finite element package ABAQUS. The model has been used to study the performance of a carbon fibre/carbon matrix-SiC matrix (C/C-SiC) plain weave laminate DLR-XT. With the effects of fibre waviness included, the global stress-strain curves, with catastrophic fracture behaviour, and the thermal conductivity-strain response have been predicted. Excellent comparisons have been made between predictions and experimental data, with fibre waviness included