Experimental and Simulation Studies on Resin Impregnation for Optimal Mechanical Properties of Glass Fiber Reinforced Polymer Composites

Abstract

The demand for applications of glass fiber reinforced composites has been increasing in aerospace, military, transport and other industries due to their enhanced mechanical properties over traditional materials. Their properties are primarily dependent on manufacturing process, reinforcement type, size, shape and percentage of reinforcement. In recent years, importance is given to the type of manufacturing for quality composite products as the machining operations are reduced. For manufacturing composites, resin transfer molding (RTM) is one of the consistent manufacturing methods and proved to be highly potential because, it allows the production of composite parts with fiber content in greater volumes at relatively low cost. newlineIn RTM process, resin injection pressure plays a vital role in the impregnation of fibers and flow front velocity of resin which finally affects the mould filling time. Resin injection at high pressure may lead to fiber washout. Moreover, location of injection port is also needed to avoid fiber washout. The injection pressure should not be low to avoid gelation problems The filling time increases with increase of fiber volume fraction at same resin injection pressure. It decreases when the resin injection pressure increases as a result, both flow front velocity of resin and permeability of fiber increase. Due to this, number of voids increases and strength of the composite decreases. Therefore, performance of laminates depends on the smart choice of key input parameters (resin injection pressure and number of layers). In the present investigations, experiments were conformed according to design of experiments (DOE). To conduct these experiments, a customized RTM with central resin injection system was fabricated to produce quality E-glass chopped strand/polyester composites with three different volume fractions at five preferred resin injection pressures. A flow visualization technique was employed to study the resin impregnating into the reinforcement and determine the filling time,