Copyright
IIT Kharagpur
xiii Abstract
Most of the composite parts that are large and complex geometry are manufactured by hand layup method. Resin Transfer Moulding (RTM) process is a better substitute to it, but is not used readily due to the lack of proper manufacturing technology. Development of a proper RTM manufacturing process for a specific application requires a proper mould design.
In addition, the difficulty in the tooling design and mould fabrication cost increases with increase in size and complexity of the component. The scale down strategy of full scale product avoids bigger size mould requirements, prototype bulk production for product testing and quality check at the starting phase of product development. Moreover, the mould scale down strategy can be used to validate the process and the product with less capital input. In this work, a methodology to develop a RTM technology for manufacturing a complex and large composite structure utilizing the process simulation were demonstrated using high speed cab front as selected component. The methodology included the development of an effective injection strategy and optimization of the process parameters for manufacturing of the cab front. Different injection schemes was proposed, simulated, and compared to obtain an effective injection strategy using the minimization of the mould fill time and formation of no dry spot as the objective. The injection strategy of four-point ports at the cab front face and four-point vents at the corners of cab front was found to be effective. The effect of processing conditions and the raw materials’ parameters on the effective injection strategy in achieving the complete RTM manufacturing process development for the cab front model was analyzed. Also a scaling down methodology based on full scale and scaled down model simulations was demonstrated. The scaled down prototype for a composite cab front was developed using isothermal moulding filling simulations based on the mould fill time and mould fill pattern comparisons between full scale and scale down model. From the simulations and actual experiments, it was found that the injection pressure at the full scale model has to be reduced to the times of reciprocal of square of geometrical mould scale down factor to meet the same mould fill time and mould fill pattern, provided the same injection strategy in both the scales. Cure kinetics, rheokinetics and gel time of the resin and the permeability of the reinforcement mat were the raw material parameters experimentally estimated to aid the RTM process simulations.
Keywords: Composite Prototype Development, Resin Transfer Moulding, Mould Filling Simulations, Mould Scaled Down Strategy, Injection Strategy
