The vacuum assisted resin infusion (VARI) process is a cost-effective technique for manufacturing lightweight large complex composite components. It belongs to the liquid composite molding (LCM) family. In this process, a fibrous preform is placed into a mold cavity, and covered by a vacuum bag, then a sealant tape is used to adhere it to the mold in order to avoid air-resin leakage. A vacuum pump is used to evacuate the air from the closed cavity which leads to compact the fabric preform. The inlet gate is opened and resin impregnates the preform under atmospheric pressure. Based on the tripping of compaction and resin infusion phases, several manufacturing routes manifest and have influence on the process time, resin pressure distribution and preform thickness uniformity. In this paper, a numerical simulation, based on the finite difference method, is conducted to investigate the effect of four major manufacturing routes of VARI process on the aforementioned parameters. The obtained results reveal that the merging of the air vacuuming and resin infusion phases has no mentioned effect on the reduction of the process time. While, the fourth manufacturing route, where the resin injection precedes vacuuming phase, is the best practice of vacuum assisted resin infusion process. In its optimum scenario, this route can reduce the process time with 19.9% as compared to the optimum scenario of the first manufacturing route.
The liquid composite molding family (LCM) includes several processes like RTM ("Resin transfer molding") and VARI ("Vacuum assisted resin infusion"), to satisfy the requirements of each industry. The objectives of recent years in the automotive and aerospace industries tend towards better control of production costs by using of new materials, shorter manufacturing cycles, a higher level of performance and safety and better environmental respect. In the automotive sector, a short cycle time and a lower cost equipment are the most criteria to determine a suitable process, while the quality of the part is the primary parameter for aeronautical process selection. The main objective of this paper is to propose and discuss a new design of LCM mold, allowing at the same time to facilitate the manufacturing process, in particular to reduce the cycle time and to respect the material's health by obtaining a part with minimum defects. This innovation is achieved by using the TRIZ theory (theory of inventive problem solving), in order to eliminate the contradictions that exist between the requirements of the two sectors.
The liquid composite molding (LCM) belongs to the composite manufacturing processes. In this family, a fabric preform material is placed into the mold cavity, and then it is impregnated with a thermosetting resin of low viscosity, until the fiber skeleton is entirely filled and finally polymerized to create a polymeric composite product. Due to its advantages, LCM has gained attention and competitiveness against other composite manufacturing processes. The resin film infusion (RFI) belongs to the LCM family, but unlike the other variants, such as resin transfer molding (RTM) and vacuum assisted resin infusion (VARI), in which the liquid resin is injected or infused into the mold cavity, the resin in the RFI process is placed into the mold cavity in the semi-cured state. Then, under pressure and temperature, the resin film will be liquefied and impregnated the fibrous reinforcement in the thickness direction. This particularity permits to RFI to fabricate large complex composite structures and reduce significantly the equipment cost as compared to the conventional resin transfer molding processes. However, as this variant used only a vacuum bag as the upper half-mold, the fabricated part has non-uniformity in the thickness, low dimensional tolerances and low fiber volume fraction. The main objective of this paper is to propose a numerical algorithm allowing to study the influence of part thickness on the RFI’ filling time. Numerical simulation is based on the explicit finite difference method. The results obtained show that the filling time increases parabolically with the part thickness.
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