Simulations of an Infrared Composite Curing Process

Abstract

Epoxy resins have several applications in the aerospace and automobile industry. Because of their good adhesive properties, superior mechanical, chemical and thermal properties, and resistance to fatigue and microcracking, they produce high performance composites. Since it is necessary to optimize the manufacturing time and costs and to determine the performance of these composites, some researchers [1][2][3][4] have studied infrared (IR) heating for the polymerization process. Others [5,6] have used IR energy for the preheating process.In the technology presented here, the composite is cured in an IR oven (see Figure 1) which includes halogen lamps. The liquid resin infusion (LRI) process is used to manufacture the composite, whereby liquid resin is infused through a fiber reinforcement previously laid up in a one-sided mold.These epoxy resins release an exothermic heat flux during the curing process, which can possibly cause an excessive temperature in the thickness. Consequently, for the production of high performance composites, it is necessary to know the thermal behavior of the composite during curing. The most detailed models for the curing process of composites using IR heaters have been presented by Chern et al. [1][2][3][4] They measured the radiative properties of graphite/epoxy and glass/epoxy systems and modeled the radiative heat transfer in the glass/epoxy system as a volumetric radiation transport. Therefore, IR interactions with the graphite/epoxy system were modeled as a surface radiation transport.Cosson et al. [7] developed numerical algorithms, based on a ray-tracing method. In-lab software, called Rayheat, predicts the volumetric distribution of the radiation intensity in a semi transparent medium. This software also models IR interactions with highly absorptive mediums, where the radiation transport is a surface radiation. In this paper, we present simulations of the IR curing process of a carbon/epoxy system. Numerical simulations were performed in order to determine the temperature distribution in the composite thickness during the polymerization process. The heat balance equation is coupled with the exothermic heat and the radiative heat flux using the commercial software Comsol Multiphysics TM . In order to introduce these simulations to an industrial composite part, we validate the simulations of a simple sheet of composite. Liquid Resin Infusion (LRI)LRI is used for the impregnation process of fibers with resin. In this process, presented schematically in Figure 2, liquid resin with low viscosity is infused through fiber reinforcement, which is placed in a single-sided mold sealed with a vacuum bag. Before being impregnated by resin, the fiber reinforcement must be preheated by the IR lamps, in order to maintain the low viscosity of the resin and to facilitate its path through the reinforcement. This process combines the advantage of infusion at ambient pressure, short cycle time and low cost equipment with the ability to produce parts of COMMUNICATION [**] Grateful acknowledgement to...

Integrated Design of D.D.I., Filament Winding and Curing Processes for Manufacturing the High Pressure Vessel (Type II)

“…The differential equations relating to displacements (u) and stiffness constants ( C ) are determined by Eqs. 13and (14). τ θr and τ zr are obtained from Eq.…”

“…, the solution for Eqs. (13) and (14) is given by Eqs. (16), (17), where D (k) and E (k) are integration constants [13]:…”

Simulation of IR Heating for Composite Stamping

“…A global heat transfer coefficient integrating selfradiation of the composite as well as free convection was used for thermal simulations. Details concerning free convection can be founded in reference [3]. In addition, the supporting frame has been neglected.…”

“…In addition, the supporting frame has been neglected. Indeed, the analysis of the experimental configuration performed by Nakouzi et al [2,3] has shown that this frame has low effect on the heating stage whether we consider the radiation or conduction interactions. The temperature profiles throughout the composites after 120 min heating are plotted in Figure 6.…”

“…In addition, computations of infrared heating have been performed thanks to numerical model previously developed based upon Comsol Multiphysics™ software [2,3]. The validity of the proposed methodology is then analysed by comparing numerical simulation results with experimental data.…”