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Thermo Polymer Matrix–Based Natural Fiber Composite
Published in Shishir Sinha, G. L. Devnani, Natural Fiber Composites, 2022
Manan Tyagi, G. L. Devnani, Raj Verma
When we talk about a feasible alternative to the autoclave process and an advanced liquid injection procedure, then RTM comes into the picture. It was deployed by industries in 1970 (Miller, 1990). In this process, resin is first heated. Resin’s viscosity should be low, and then is injected into a pre-decided shape or form in a closed mold for dry reinforcement (Jamir et al., 2018). The resin is injected at pressure between 0.4 to 1 MPa for the superior impregnation of matrix into reinforcement. To obtain certain performance, the resin is cured under pressure (Mallick, 2010b). The advantages of RTM include less tooling and setup cost, less amounts of defects, and excellent finish on both surfaces. Using the RTM method, rudder tips, ribs, and panels of airplanes are fabricated (Meola et al., 2017).
Manufacturing techniques for polymer composites used in construction
Published in Peter Domone, John Illston, Construction Materials, 2018
Resin-transfer moulding is a low-pressure, closed mould semi-mechanised process. In the RTM process, several layers of dry continuous strand mat, woven roving or cloth are placed in the bottom half of a two-part closed mould and a low-viscosity catalysed resin is injected under pressure into the mould cavity, and cured. Flat reinforcing layers, such as a continuous strand mat, or a ‘preform’ that has already been shaped to the desired product, can be used as the starting material in this process. The potential advantages of RTM are the rapid manufacture of large, complex, high-performance structures with good surface finish on both sides, design flexibility and the capability of integrating a large number of components into one part. This method can be employed to form large components for all composite bridge units but it is not often used.
Bio-Fiber Thermoset Composites
Published in Omar Faruk , Jimi Tjong , Mohini Sain, Lightweight and Sustainable Materials for Automotive Applications, 2017
Ashok Rajpurohit, Frank Henning
The RTM process technique has the advantage of rapid manufacturing of large, complex, and high performance parts. Several types of resins (epoxy, polyester, phenolic, and acrylic) can be used for RTM as long as their viscosity is low enough to ensure a proper wetting of the fibers. The hemp fiber composites manufactured with this RTM process were found to have a very homogeneous structure with no noticeable defects. The mechanical properties of these materials were found to increase with increasing fiber content [47,48]. In this study, it was also shown that the processing time for a 35 vol% hemp fiber composite could be decreased to 40 min from almost 2 h presently without any major changes to the set-up. In order to achieve high fiber contents with hemp fibers in a process such as RTM, the need of a prepressing stage at 100°C was suggested. This additional step reduced greatly the spring-back behavior of the fibers, making the closure of the mold much easier. Oksmann [49] in her study on flax-based epoxy composite concluded that RTM is a suitable processing technique for natural fiber composites when high quality laminates are preferred. Idicula and colleagues [47] and Rodriguez and colleagues [50] reiterated such an observation in the case of hybrid natural fiber composites manufactured using RTM.
Investigation of the bending behaviour of multi-ply dry carbon fibre non-crimped fabrics
Published in The Journal of The Textile Institute, 2018
Timo Grieser, David Becker, Peter Mitschang
Resin Transfer Moulding (RTM) is an established liquid composite moulding (LCM) process, which potentially allows realization of mass production (Neitzel, Mitschang, & Breuer, 2014). The RTM process chain can be split into two main phases: preforming (fibre structure preparation) and injection (impregnation of the fibre structure with a matrix system). In this context, compared to the injection phase, the efficiency and robustness of the preforming phase is more deficient and can therefore be seen as a key element for further improvement of RTM, respectively, LCM (Arnold, Rieber, & Mitschang, 2012).
The effect of molding process on thermomechanical properties of feather nonwoven reinforced polyester composites
Published in The Journal of The Textile Institute, 2022
Ouahiba Mrajji, Mohamed El Wazna, Abdeslam El Bouari, Omar Cherkaoui
Several molding techniques can be applied for feather nonwoven reinforced composite fabrication. Some are based on the polymerization of the polymer in the mold. One of these methods is ‘resin transfer molding’ (RTM). In this process, the fiber reinforcement is put in a mold cavity and the resin is introduced by injection. In comparison with the other methods, RTM is a simple and economical method. The only problem with this method is the low fiber volume fraction, which could also be overcome by using denser fibers. In RTM, the catalyzed resin is injected under a pressure of 1000 bar into the mold through a properly positioned injection port. The injection is stopped when the mold is completely filled with the resin, and the sample is subsequently cured. After the polymerization, the sample is removed from the mold (Van den Broek d’Obrenan, 2011). The vacuum molding process is similar to contact molding, except that it is carried out under a vacuum of 500 bars. The first step in vacuum molding is to prepare the mold to receive the different types of reinforcements; a release agent can be applied to facilitate the demolding of the sample. The reinforcement in the form of mat or tissue is impregnated with resin, usually manually, until the desired thickness. The air is emptied from the mold and once the polymerization is complete, the sample is demolded (Merad, 2010). Infusion molding was developed to reduce the costs and constraints associated with the use of RTM. It doesn't require the use of a counter-mold or oven, which reduces investment costs and sample size limitations. In infusion molding, reinforcements are installed in the mold and then the vacuum system is applied. The air is removed from the mold and the catalyzed resin is injected inside the mold under a low pressure of 500 bar (Blais et al., 2016).
Parallel optimization of design and manufacturing—Carbon fiber battery pack for electric vehicles
Published in Mechanics of Advanced Materials and Structures, 2022
Qi-hua Ma, Fan Dong, Xiao-yu Qin, Xue-hui Gan, Ming Cai
The excellent performance and designable features of carbon fiber composites should have achieved rapid development in various transportation fields, but the immaturity of the process technology has limited its large-scale application. The molding method, hand layup, vacuum infusion, split forming, and vacuum bagging method [19–21]. Among them, the resin transfer molding (RTM) molding process is used for the mass production of composite parts with high precision, high efficiency, and low cost [22]. Shi and Dong [23] discussed the time analysis step, heat of reaction, thermal conductivity of the fibers and resin, and initial temperature of the fibers for the RTM process. Djebara et al. [24] developed an RTM global modeling approach based on previous work to simulate the resin flow during RTM fabrication and predict the effective heat transfer of the composite. Huang et al. [25] revealed the whole process of resin flow and infiltration during the molding process by numerical simulation to visualize the process. Shimada et al. [26] focused on the numerical simulation of defect prediction during RTM molding, using boundary element and line dynamics methods to simulate small molding defects by adding nodes at desired locations in the time evolution process. The level of RTM is increasingly advanced by researchers, but they focus only on the parameters of the curing process and ignore the presence of molding defects. Combined with the heavy difficulties of actual carbon fiber processed products, cutting and layup are the most important processes in RTM molding. Most of the current scheme designs realize the preprocessing performance prediction by finite element technology, which ignores a difficult point, namely, the fiber bundle cluttering at the fiber cutting. To solve the fiber uncontrollability problem, preprocessing simulation of the product before manufacturing is performed by Fiber Sim software in this paper to achieve the parallel structural design-manufacturing optimization [27, 28].