THE EFFECT OF ANISOTROPIC THERMAL CONDUCTIVITY ON THE PULTRUSION PROCESS SIMULATION

Abstract

The composite materials have been used in a large set of commercial products (space and aeronautical structures, automotive panels, tennis rackets, among others). One of the lower-cost processes for manufacturing bars of composite materials with constant cross-section is the pultrusion. In this process, a fiber creel is impregnated in a resin bath and passes through a heated die with a constant pulling speed, where the high die temperature induces the resin cure exothermic reaction. At the present study, the energy and the kinetics of cure equations are discretized by the finite element method with an unstructured triangular mesh. The obtained algebraic equations system is iteratively solved. Usually, the pultrusion process simulation is performed supposing isotropic thermal properties, that is, equal thermal conductivity in the composite material bar axial and transversal directions. This work reports the effect of the anisotropic thermal conductivity on the degree of cure and temperature profiles. Three cases are studied: in the first one, the axial conduction is neglected (parabolic approach); in the second case, isotropic thermal conductivity is assumed (first elliptic approach). In the last one, the carbon fiber anisotropic property is carried on the solution (second elliptic approach). The influence of the convective to diffusive transport terms ratio on the obtained results for the composite bar curing process is also analyzed. It is shown that in convective-dominant problems (high pulling speed) the fiber thermal conductivity anisotropy influence is less significant.