The characterisation and modelling of manufacturing porosity of a 2-D carbon/carbon composite

The thermal properties of carbon/carbon composite are strongly affected by manufacturing porosity. This paper focuses on the characterisation of the manufacturing macro-porosity of a 2D carbon/carbon composite using X-ray computed tomography. The different types of manufacturing porosity were classified and quantified according to their size and location. Three types of macro-porosity were identified using computed tomography, namely trans-tow cracks, interfacial cracks and dry zones. A composite unit cell representing the three types of porosity was developed to model and investigate the effective transverse thermal transport properties (thermal conductivity and diffusivity) of the carbon/carbon composite. Finite element simulations and theoretical calculations were performed and compared with laser flash tests for validation. The influence of the stacking sequence of the laminates on porosity distribution and transverse thermal conductivity of the carbon/carbon composite was also investigated.