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Plant Fiber-Reinforced Thermoset and Thermoplastic-based biocomposites
Published in Shakeel Ahmed, Saiqa Ikram, Suvardhan Kanchi, Krishna Bisetty, Biocomposites, 2018
High strength, energy absorption, and stiffness are obtained by composite materials, which are widely used in automotive and motorsport sectors mainly due to the property of mass reduction. Enhanced energy absorption is evident from the increased volume fraction, which is possible only in the presence of low speed such as 2.5m/s. On the other hand, at high speeds such as 300m/s, similar performance is shown by flax, jute, and hemp, but jute showed brittleness and low strength of fibers. The potential of NFPCs, which is required for application in providing sustainable energy absorption, was investigated by Meredith et al. while keeping focus on motorsport [64]. Vacuum-assisted resin transfer molding (VARTM) manufacturing is used to test conical specimens of jute, hemp, and flax for their features and properties. The values showed by different kinds of materials were recorded to analyze specific energy absorption (SEA).
Manufacturing Processes
Published in Ever J. Barbero, Introduction to Composite Materials Design, 2017
Ever J. Barbero, Ever J. Barbero
In Vacuum-Assisted Resin Transfer Molding (VARTM), the vacuum is applied to the outlet of the mold and the resin is drawn into the mold by vacuum only. A schematic of the process is shown in Figure 3.5. The pressure applied to the impregnated reinforcement is due to the pressure differential between the vacuum applied and the atmospheric pressure action on the exposed surface of the vacuum bag. Since vacuum is applied instead of pressure, half of the mold may be replaced by a vacuum bag. Resin flow can be assisted by microgrooves built into the mold or into a distribution medium placed beneath the vacuum bag. Some aspects of this technology are patented and commercialized under the name SCRIMP™ [179]. Since the pressure differential is much lower than the pressure used in conventional RTM, and curing is most commonly done at ambient temperature, the cost of the mold can be reduced substantially; heavy steel molds needed in pressurized RTM can be replaced by lighter molds made of wood, epoxy, or light-gage steel. Cycle times for this process range from minutes to hours for large complex parts. Typical applications of VARTM include large, complex parts such as boat hulls and so on.
Bio-Fiber Thermoset Composites
Published in Omar Faruk , Jimi Tjong , Mohini Sain, Lightweight and Sustainable Materials for Automotive Applications, 2017
Ashok Rajpurohit, Frank Henning
An alternative variant of this process is vacuum injection or vacuum-assisted resin transfer molding (VARTM), where a single solid mold and a foil (polymeric film) are used. This process has also been widely reported for bio-fiber thermoset composite manufacturing. One such study is reported by Rodriguez et al. [51], where they studied mechanical properties of composites based on different natural fibers and glass fibers using unsaturated polyester and modified acrylic as matrix manufactured using a vacuum infusion process. The VARTM process is a very clean and low cost manufacturing method: resin is processed into a dry reinforcement on a vacuum-bagged tool, using only the partial vacuum to drive the resin. As one of the tool faces is flexible, the molded laminate thickness depends partially on the compressibility of the fiber-resin composite before curing and the vacuum negative pressure.
Numerical study on filling process in progressive compression method
Published in Advanced Composite Materials, 2019
Vacuum infusion (VI), also known as vacuum assisted resin transfer molding (VARTM), is one of the most attractive methods for the manufacture of composite parts. In a typical VI process, the dry preform is placed on the rigid mold and sealed with an elastic bag to create an airtight mold cavity. After the vacuum is applied in the mold cavity, the inlet line is opened and the resin is driven by atmospheric pressure through the infusion line. The resin flow pressure also results in preform thickness variation due to the flexibility of the polymeric bag, as illustrated in Figure 1. After the preform is fully saturated, the removal of the unnecessary resin from the wetted preform, called post-filling stage, is necessary for the sake of achieving the uniform thickness of the part.