Numerical Investigation of The Effect of Needling Diameter on Effective Thermal Conductivity of 3D C/C Composite A report submitted to Umm Al-Qura University for the degree of MSc in Mechanical Engineering Department

Abstract

Carbon-Carbon composite are considered as a ceramic matrix composite. Two-dimensional C/C composite have low inter-laminar strength and low through thickness thermal conductivity. Needle-punching process enhances the properties in through-thickness direction. The needling process has a direct effect on thermal properties and porosity distribution in the composite. In this study, the effect of needling diameter on the effective thermal conductivity of the C/C composite was determined through multiscale finite element modeling. The structure of a 3D needled C/C composite was examined using Scanning Electron Microscopy and X-ray Tomography. Thermal conductivity and thermal diffusivity ware measured in the longitudinal and through-thickness directions using the Laser Flash Test. It was found that the through-thickness thermal conductivity of the composites increased with increasing needling diameter. The longitudinal thermal conductivity of the composite decreased with the increase in needling diameter. Whereas the through-the-thickness thermal conductivity of the composite increased with increasing needling diameter.