NUMERICAL ANALYSIS OF INFUSION STRATEGIES IN VACUUM ASSISTED RESIN TRANSFER MOLDING (VARTM) PROCESS

The Liquid composite Molding (LCM) process, such as Vacuum Assisted Resin Transfer Molding (VARTM), offers a fast and high-quality production of composites laminates. In the VARTM process, the simulation tool is found beneficial to predict and solve composite manufacturing issues. The part quality is dependent on the resin mold filling stage in the VARTM process. The infiltration of resin into a porous fibrous medium is taken place during the resin mold filling stage. The permeability has a crucial role during the resin mold filling stage. In this study, simulation of resin infusion through multiple injection gates is discussed. The various infusion schemes are simulated to identify defect-free composite manufacturing. The simulation approach is applied to five different stacking sequences of reinforcements. In this transient simulation study, permeability and resin viscosity is essential inputs for the resin flow. The simulation approach found that a gating scheme plays a vital role in mold filling time and defect-free composite fabrication. It is found that the line gating system can be useful for fast mold filling over the point gating system.

Degassing and layers variation effect on composite processing by vacuum assisted resin transfer moulding

Vacuum assisted resin transfer molding (VARTM) is a fiber reinforced composite (FRC) making process in which resin is impregnated to fabric by application of vacuum. This process is also known as vacuum infusion process. The critical issue in VARTM process is void generation. Voids form due to variety of reasons, most of which can be avoided. Vacuum degassing is one of the solutions which will reduce air entrapped inside resin during impregnation. In this work six laminates from jute and polyester resin were prepared, three with degassing and three without degassing with variation in number of jute layers 5, 10 and 15 respectively. Microscopic examination and mechanical properties have been observed before and after degassing. It was observed that degassing improves mechanical properties of composite laminates and reduce void content. It was observed that the thickness variation in laminate increased as number of layer increased.

Development of fiber-reinforced transparent composites

In this study, a continuous glass fiber-reinforced composite is manufactured using the vacuum assisted resin transfer molding (VARTM) process. The composite is manufactured from an S-glass fiber acting as reinforcement and an epoxy resin as matrix. Unlike a traditional E-glass fiber reinforcement, S-glass fibers give higher stiffness and provide easier manufacturability due to the value of the refractive index of S-glass lying within the range of refractive indices of the epoxy resin. The epoxy resin is synthesized Epon 826, Epalloy 5200, and hexahydropthalic anhydride and tailored to match refractive indices of the S-glass fibers. After synthesis of the resin, composite panels are manufactured from the synthesized epoxy resin and S-glass fibers with a bi-directional [0°/90°] 8-harness satin weave. VARTM process was utilized to manufacture the composite panels. Composite panels are visually inspected for transparency, and tensile, flexural, and impact testing is performed. Mechanical tests showed consistent results for tensile modulus, tensile strength, flexural modulus, flexural strength, and impact damage resistance.

Axial Compression Properties of Special-Shaped 3D Tubular Woven Composites

Axial compression properties of special-shaped 3D tubular woven composites with basalt fiber filament tows were studied. Special-shaped 3D tubular woven fabrics composites with three different thicknesses were woven on an ordinary loom and fabricated by the vacuum assisted resin transfer molding (VARTM) process. Load-displacement and energy-displacement curves were obtained from experimental tests. Results showed that for special-shaped 3D tubular woven composites, the load and energy absorption were greater with thickness and the compression property improved. Through the analysis of the mathematical equation and correlation coefficient of the load-displacement and energy-displacement relation, the fitting effect of the curves were good. The mathematical equation of the method could be used to simplify the functional relationship between load, energy, and displacement.