The identification of effective thermal conductivity for fibrous reinforcement composite by inverse method

Abstract

In the present work, the thermal conductivity of a composite material is determined by inverse analysis of the heat conduction phenomenon in resin transfer molding process. The Gauss–Newton–Levenberg–Marquardt method was utilized to identify the thermal conductivities of fibrous reinforcement. Knowing the boundary conditions, the thermal conductivity can be deduced from the temperature values at some given positions through the part. Starting from an initial estimate of thermal conductivity, the inverse method begins by solving the direct problem, i.e. the heat equation. The solution gives the temperature field everywhere in the composite sample. Calculated temperatures are then compared with analytical temperatures based on a criterion. Conductivity is modified iteratively so as to minimize this criterion until the desired accuracy is achieved. The identified thermal conductivity by the inverse methodology was validated with experimental results of epoxy composites with carbon nanotube and chopped carbon fibers. Satisfactory agreement was obtained. Furthermore, this method offer the possibility to determinate conductivity of several part of composite at the same time, and could be generalized for bio composite, so it can be considered as accurate and economically efficient technique in the prediction of thermal conductivity of composite.