An inverse approach to characterize anisotropic thermal conductivities of a dry fibrous preform composite

Abstract

Fiber-reinforced composites play an important role in enabling the industrial composites industry including automotive, pressure vessels etc. to meet ever increasingly aggressive fuel efficiency requirements. Modeling and analysis is often employed in composite development as a tool to achieve faster and more cost-effective solutions to both product and process designs. Thermal conductivity measurements play a critical role in enhancing the fidelity of these models, especially in scenarios involving non-isothermal processing. Accurate characterizations of anisotropic thermal conductivities that are typical of dry fibrous preforms are especially challenging because of their highly porous and complex structures. In this article, an inverse approach is developed to estimate the anisotropic thermal conductivities of a dry preform made of biaxial [0°/90°] stitched glass-fiber mats based on the measurements of thermal conductivities of cured epoxy-matrix composites. This method is found to not only yield more accurate results than direct preform measurements but also provide the capability to characterize preforms in multiple directions rather than only through-thickness direction. The estimated thermal conductivities are used in preform heating simulation that is validated against experiments.