Journal articles: 'Vacuum assisted resin transfer molding (VARTM)'

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Chang, Chih-Yuan. "Numerical study of filling strategies in vacuum assisted resin transfer molding process." Journal of Polymer Engineering 35, no. 5 (June 1, 2015): 493–501. http://dx.doi.org/10.1515/polyeng-2014-0237.

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Abstract During the filling process of vacuum assisted resin transfer molding (VARTM), the infusion pressure gradient causes the resin flow and preform thickness variation. Even after the resin infusion discontinues, the resin keeps on flowing until the unnecessary resin is removed. In this study, a one-dimensional flow model coupled to the preform deformation is numerically analyzed to assess the influences of various processing scenarios on the infusion and post-infusion stages. The numerical model is implemented using a finite difference method. Results show that two strategies effectively reduce the filling process. One is to infuse less excess resin and the other is to turn the inlet into the additional vent. For a typical process using a one-sided vent, the theoretically optimum scenario is to infuse the exact required resin volume into the preform. From a practical standpoint, excess resin infusion is inevitable and a robust scenario is proposed by integrating the concept of fully filled preform and two strategies. Additional cases are performed using a vacuum assisted compression RTM (VACRTM) process for comparison purposes. Through the numerical work, a tool for optimization of the VARTM process is provided to reduce the filling process, resin waste and variability in the final composite part.

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Chang, Chih-Yuan, and Hung-Jie Lin. "Unsaturated polyester/E-glass fiber composites made by vacuum assisted compression resin transfer molding." Journal of Polymer Engineering 32, no. 8-9 (December 1, 2012): 539–46. http://dx.doi.org/10.1515/polyeng-2012-0071.

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Abstract A variant process incorporating the method of bag compression into resin transfer molding (RTM), called vacuum assisted compression RTM (VACRTM), has been developed to reduce the cycling period and improve the quality of the part. The process utilizes a flexible bag placed between the upper mold and the preform compared with RTM. By controlling the stretchable bag, the resin is easily introduced into the cavity filled with a loose preform. Then, ambient pressure is applied on the bag that compacts the preform and drives the resin through the remaining dry preform. The objective of this research is to explore the simplified VACRTM feasibility and investigate the effects of process variables, including resin temperature, resin infusion pressure, mold cavity height and cure temperature, on the mechanical strength of the part, by applying Taguchi’s method. The results show that VACRTM has advantages in terms of its being an easy and good seal among mold parts and the the lack of a need to clean the upper mold. The resin infusion pressure is a significant variable for improvement of the mechanical strength of the part. Optimal VACRTM reduces the filling time by 58% and increases the flexural strength by 10%, as compared with typical vacuum assisted RTM (VARTM).

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Xia, Changlei, Sheldon Q. Shi, Liping Cai, and Jun Hua. "Property enhancement of kenaf fiber composites by means of vacuum-assisted resin transfer molding (VARTM)." Holzforschung 69, no. 3 (April 1, 2015): 307–12. http://dx.doi.org/10.1515/hf-2014-0054.

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Abstract This work was aimed at applying vacuum-assisted resin transfer molding (VARTM) technique to reinforced polymer molding products made of vegetable fibers. Kenaf (Hibiscus cannabinus L. Malvaceae) bast fibers were preformed into mat by means of a cold press. The unsaturated polyester resin was infused into the preforms at a vacuum pressure of 1.3–1.6 kPa. The examination of the mechanical properties and microstructure of the prepared composites indicated that the modulus of elasticity (MOE), modulus of rapture (MOR), and tensile strength (TS) of the VARTM composites were increased by 65.5%, 30.7%, and 41.7%, respectively, compared to the traditional hot-pressing composites. The dynamic mechanical analysis (DMA) revealed that the VARTM composite moduli in the temperature range of -50°C–200°C were doubled. The observations by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and mercury porosimetry confirmed that the interfacial compatibility between the kenaf fibers and the polyester resin was substantially improved.

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Ouezgan, Ahmed, Said Adima, Aziz Maziri, El Hassan Mallil, and Jamal Echaabi. "Relaxation-Compression Resin Transfer Molding under Magnetic Field." Key Engineering Materials 847 (June 2020): 81–86. http://dx.doi.org/10.4028/www.scientific.net/kem.847.81.

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Relaxation-compression resin transfer molding under magnetic field is a new variant of VARTM (“vacuum assisted resin transfer molding”) process, which uses a flexible magnetic membrane controlled by a magnetic force, in order to govern the relaxation and compression phases by changing the permeability of the fabric preform. Thus permits to the resin to enter easily into the mold and to increase the resin impregnation velocity and the fiber volume fraction. This innovation is based on the application of the TRIZ theory (“the theory of inventive problem solving”), which allows us to answer to the shortcomings and the conflict links exist inside the VARTM processes. The objective of this paper is to present this new process and to study the effect of the current intensity and the separated gap between the flexible magnetic membrane and solenoid on the permeability of the preform.

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Loudad, Raounak, Abdelghani Saouab, Pierre Beauchene, Romain Agogue, and Bertrand Desjoyeaux. "Numerical modeling of vacuum-assisted resin transfer molding using multilayer approach." Journal of Composite Materials 51, no. 24 (January 5, 2017): 3441–52. http://dx.doi.org/10.1177/0021998316687145.

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Vacuum-assisted resin transfer molding (VARTM) is a very suitable solution for composite manufacturing industry. It allows the manufacturing of large and complex shape parts at low costs. However, the simulation of this process is complicated due to myriad physical phenomena involved, specifically the strong coupling between the resin flow and the preform compressibility, i.e. hydro-mechanical coupling. Moreover, the use of the distribution medium involves two types of flow: Planar flow and through-the-thickness flow. These flows cannot be considered together by a 2D model. On the other hand, 3D models require an important amount of computation time. This article presents a VARTM modeling approach that takes into account the hydro-mechanical coupling and the coexistence of planar and transverse flows. The proposed modeling approach allows the simulation of the infusion process in the case of multilayer preform with different materials and orientations, including the distribution medium. This model is validated experimentally based on several infusions.

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Kim, Yun Hae, Dong Hun Yang, Chang Won Bae, Kyung Man Moon, Young Dae Jo, Sung Won Yoon, and Hee Beom An. "Glass Fiber Permeability Using the VARTM Process." Advanced Materials Research 97-101 (March 2010): 1772–75. http://dx.doi.org/10.4028/www.scientific.net/amr.97-101.1772.

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This study investigated a flow rate control system for the vacuum-assisted resin transfer molding (VARTM) process. Using Darcy’s equation, the permeability of multiaxial glass fiber composites is predicted and experimentally confirmed. The resin velocity vector is inversely proportional to the fiber mat length and resin viscosity, but proportional to the fiber mat permeability. In this study, the permeability of the preform and viscosity of the epoxy resin were measured using multiaxial glass fiber by VARTM. The permeability and time for impregnation differed according to the fiber direction in the VARTM process. The results indicated the need for further study of reinforcement fiber permeability in VARTM processing design.

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Sales, Rita de Cássia Mendonça, Silas Rodrigo Gusmão, Ricardo Francisco Gouvêa, Thomas Chu, José Maria Fernandez Marlet, Geraldo Maurício Cândido, and Maurício Vicente Donadon. "The temperature effects on the fracture toughness of carbon fiber/RTM-6 laminates processed by VARTM." Journal of Composite Materials 51, no. 12 (November 25, 2016): 1729–41. http://dx.doi.org/10.1177/0021998316679499.

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The increasing use of composite in the aircraft industry has raised the interest for a better understanding of the failure process in these materials, which can be also influenced by the manufacturing process of the laminate. Some materials used in vacuum assisted resin transfer molding process have been studied in the open literature but very few data have been published for resin transfer molding-6 epoxy based laminates, in particular studies showing the influence of the temperature on the interlaminar fracture behavior of this type of laminates. The aim of this article is to investigate the interlaminar fracture behavior of resin transfer molding-6 based carbon composite laminates manufactured by vacuum assisted resin transfer molding subjected to Modes I and II at 25℃ and 80℃. The results show the influence of the temperature on the interlaminar fracture toughness of composites and provide a database to design composite aerostructures subjected to temperatures commonly experienced in civil aviation. The fracture aspects of the tested laminates were also investigated and directly related to the trend in results found for the fracture toughness values.

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Correia, N. C., F. Robitaille, A. C. Long, C. D. Rudd, P. Sˇima´cˇek, and S. G. Advani. "Use of Resin Transfer Molding Simulation to Predict Flow, Saturation, and Compaction in the VARTM Process." Journal of Fluids Engineering 126, no. 2 (March 1, 2004): 210–15. http://dx.doi.org/10.1115/1.1669032.

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The present paper examines the analysis and simulation of the vacuum assisted resin transfer molding process (VARTM). VARTM differs from the conventional resin transfer molding (RTM) in that the thickness of the preform varies during injection affecting permeability and fill time. First, a governing equation for VARTM is analytically developed from the fundamental continuity condition, and used to show the relation between parameters in VARTM. This analytical work is followed by the development of a numerical 1-D/2-D solution, based on the flow simulation software LIMS, which can be used to predict flow and time dependent thickness of the preform by introducing models for compaction and permeability. Finally, the results of a VARTM experimental plan, focusing on the study of the influence of outlet pressure on compaction and fill time, are correlated with both the analytical and the numerical work. The present work also proposes an explanation for the similarities between VARTM and RTM and shows when modeling VARTM and RTM can result in an oversimplification.

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KIM, YUN-HAE, JIN-HO SON, BYUNG-KUN CHOI, YOUNG-DAE JO, KUK-JIN KIM, and JOONG-WON HAN. "EVALUATION OF MECHANICAL PROPERTIES OF CFRP BY VARTM AND ITS APPLICATION." International Journal of Modern Physics B 20, no. 25n27 (October 30, 2006): 3896–901. http://dx.doi.org/10.1142/s0217979206040556.

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In the present study, we contrast the change of mechanical and physical properties between VaRTM (Vacuum Assisted Resin Transfer Molding) and hand lay-up process. In the results of mechanical tests, VaRTM specimen is stronger than hand lay-up specimen and hand lay-up specimen became delamination. In the results of physical tests, the resin content of VaRTM specimen is lower than hand lay-up specimen. On micrograph, the strength of specimen by VaRTM between fiber and resin is stronger than that of one by hand lay-up. And the specimen by hand lay-up contains more defects than one by VaRTM. So, VaRTM process can practically apply for automobile engine hood. This paper shows that VaRTM process is one of the most suitable processes for composite parts of automobile.

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Walsh, Shawn M., and Colin E. Freese. "Numerical model of relaxation during vacuum-assisted resin transfer molding (VARTM)." Polymer Composites 26, no. 5 (2005): 628–35. http://dx.doi.org/10.1002/pc.20135.

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Bender, Dominik, Jens Schuster, and Dirk Heider. "Flow rate control during vacuum-assisted resin transfer molding (VARTM) processing." Composites Science and Technology 66, no. 13 (October 2006): 2265–71. http://dx.doi.org/10.1016/j.compscitech.2005.12.008.

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Kim, Yun-Hae, Kyung-Man Moon, Byeong-Woo Lee, Joon-Young Kim, Dong-Hun Yang, Sung-Won Yoon, Hee-Beom An, and Seung-Jun An. "AN EXPERIMENTAL STUDY OF MICRO-VOID CREATION BY IMPURITY IN COMPOSITE MATERIALS DURING VARTM PROCESS." International Journal of Modern Physics B 25, no. 31 (December 20, 2011): 4204–7. http://dx.doi.org/10.1142/s0217979211066581.

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The effects of impurities on the generation of voids in composites fabricated by vacuum-assisted resin transfer molding was investigated to help reduce mechanical weakening in large structures. Impurities were intentionally inserted into laminates, which were then observed optically. Internal voids were generated in specimens with impurities of 2 – 3mm thickness. The voids grew as the impurities' thicknesses increased to 4 – 5 mm. The voids' diameters were proportional to the thickness of the impurity. Void generation was shown to depend on the thickness of impurities. Environmental control during vacuum-assisted resin transfer molding was shown to be important for ensuring the quality of the resulting composites.

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Nakanishi, Eitoku, Seijiro Maki, and Satonori Matsumoto. "Molding of C-FRP Plate with Using Induction Heating." Advanced Materials Research 410 (November 2011): 345–48. http://dx.doi.org/10.4028/www.scientific.net/amr.410.345.

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Recently, the market for composite materials is dominated by small and medium series production and prototyping [1]. And the VaRTM (Vacuum assisted Resin Transfer Moldings) process is thought to be low cost composite fabrication technique [2]. The preforms in VaRTM are placed on one–side mold and they are sealed by a flexible vacuum bag [3]. The resin is infused into dry fabric formed on a mold near product shape under vacuum pressure and cured in an oven. In general, part defects often arise during the mold filling stage of the process, where a resin is drawn into performs through the use of vacuum. Uniform fill of resin and complete fiber saturation are required for fabricating high quality products [5]. So the resin flow control is extremely required. To solve these problems and short time fabrication, this article investigates the new molding process of C-FRP plate with using the combination of induction heating for quick heating and vacuuming method. To control of the volume fraction easily and to achieve homogeneous impregnation, thermoplastic resin sheet was chosen instead of liquid type. And the C-FRP in a size of 120mm*120mm and the thickness is 6.6mm was able to fabricate by this method.

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Hsiao, K.-T., R. Mathur, S. G. Advani, J. W. Gillespie,, and B. K. Fink. "A Closed Form Solution for Flow During the Vacuum Assisted Resin Transfer Molding Process." Journal of Manufacturing Science and Engineering 122, no. 3 (September 1, 1999): 463–75. http://dx.doi.org/10.1115/1.1285907.

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A closed form solution to the flow of resin in vacuum assisted resin transfer molding process (VARTM) has been derived. VARTM is used extensively for affordable manufacturing of large composite structures. During the VARTM process, a highly permeable distribution medium is incorporated into the preform as a surface layer. During infusion, the resin flows preferentially across the surface and simultaneously through the preform giving rise to a complex flow front. The analytical solution presented here provides insight into the scaling laws governing fill times and resin inlet placement as a function of the properties of the preform, distribution media and resin. The formulation assumes that the flow is fully developed and is divided into two regimes: a saturated region with no crossflow and a flow front region where the resin is infiltrating into the preform from the distribution medium. The flow front region moves with a uniform velocity. The law of conservation of mass and Darcy’s Law for flow through porous media are applied in each region. The resulting equations are nondimensionalized and are solved to yield the flow front shape and the development of the saturated region. It is found that the flow front is parabolic in shape and the length of the saturated region is proportional to the square root of the time elapsed. The results thus obtained are compared to data from full scale simulations and an error analysis of the solution was carried out. It was found that the time to fill is determined with a high degree of accuracy while the error in estimating the flow front length, d, increases with a dimensionless parameter ε=K2xxh22/K2yyd2. The solution allows greater insight into the process physics, enables parametric and optimization studies and can reduce the computational cost of full-scale 3-dimensional simulations. A parametric study is conducted to establish the sensitivity of flow front velocity to the distribution media/preform thickness ratio and permeabilities and preform porosity. The results provide insight into the scaling laws for manufacturing of large scale structures by VARTM. [S1087-1357(00)02002-5]

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Kim, Yun Hae, Jin Woo Lee, and Jun Mu Park. "Flow Characteristics of Vacuum Assisted Resin Transfer Molding Process Depending on the Capillary Phenomenon." Materials Science Forum 762 (July 2013): 612–20. http://dx.doi.org/10.4028/www.scientific.net/msf.762.612.

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Reducing the cost of composite material production is significant for expanding its usage and application in many ways, such as in the fields of aerospace, aviation, ocean industry and so on. To do this, It is important to minimize the production process of the material and to decrease the amount of scraps or any unnecessary particles. The Vacuum Assisted Resin Transfer Molding (VARTM) process, which is known for having many advantages, has become recognized as one of the most low-cost manufacturing model. VARTM process can be divided into three main steps: performing, resin filling and hardening steps. The most important step among all these three steps is the Resin Filling stage, a process when resin is impregnated into the mat. Mostly, Resin Filling stage is greatly affected by the level of permeability, a characteristic of stiffener due to pneumatic resistant nature in the process. Other factors such as viscosity, technological vacuuming, or even stiffening process itself could also influence the production as well. During Resin Filling stage, Resin tends to spread out in the center first because of capillary phenomenon. In this research, the researchers examined the mechanical property and the pneumatic nature of Resin by dividing the pneumatic movement of the Resin into sections. Based on this result, the researchers found the correlations between the capillary phenomenon and Resin impregnation, and analyzed the movement mechanism in Resin filling stage.

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Li, Yan Liang, Xiao Su Yi, and Bang Ming Tang. "The Thickness and the Inerior Quality of Composite Panel in the Vacuum Assisted Resin Transfer Molding Process." Materials Science Forum 686 (June 2011): 468–73. http://dx.doi.org/10.4028/www.scientific.net/msf.686.468.

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The objective of this paper was focused on predicting the thickness and the interior quality of carbon fiber composite panel during the vacuum assisted resin transfer molding (VARTM) process. The character of the VARTM process determined that it was low cost. A panel made of Epoxy resin, and carbon fibers, was used as the simplest article to experiment and except routine items, the thickness and the interior quality was focused. In the process, the flow front of the resin was record using a digital camera. Darcy’s law was the model of resin flow. The results showed that the flow front history would reach unanimous, thickness near the edges was difficult to control, and most of the porosity came from the injection line where more resin cumulated.

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Chen, Dingding, Sangjae Yoon, Kazuo Arakawa, and Masakazu Uchino. "Laminate Thickness Evolution during the Resin Infusion Step of Vartm." Advanced Composites Letters 23, no. 6 (November 2014): 096369351402300. http://dx.doi.org/10.1177/096369351402300601.

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The entire infusion step in a vacuum-assisted resin transfer molding (VARTM) process was measured by a three-dimensional digital image correlation (DIC) testing system. The results showed that a stack of fibre reinforcements initially shrank and then expanded as the resin filled the cavities before closing the inlet. The full-field thickness change distribution calculated from 3D DIC revealed zones that were unsaturated, partly saturated, and fully saturated with resin.

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Kedari, Vishwanath R., Basil I. Farah, and Kuang-Ting Hsiao. "Effects of vacuum pressure, inlet pressure, and mold temperature on the void content, volume fraction of polyester/e-glass fiber composites manufactured with VARTM process." Journal of Composite Materials 45, no. 26 (September 21, 2011): 2727–42. http://dx.doi.org/10.1177/0021998311415442.

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Vacuum-assisted resin transfer molding (VARTM) process is one of the liquid composite molding (LCM) processes aimed at producing high-quality composite parts. The void content and fiber volume fraction of a VARTM part can be affected by many parameters and is critical to the mechanical properties and the quality of the part. In this paper, a series of experiments were conducted with a heated dual pressure control VARTM setup for investigating the effects of vacuum pressure, inlet pressure, and mold temperature on the void content and fiber volume fraction of polyester/E-glass fiber composite. It was found that stronger vacuum and higher mold temperature can better control and increase the fiber volume fraction; however, such a combination of strong vacuum and high mold temperature may also require a reduced inlet pressure for minimizing the void content. The need of pressure reduction can be explained with the compatibility between Darcy's flow and capillary flow in the fiber preform and can be calculated based on the room temperature VARTM results. The experimental results suggest that high mold temperature, high vacuum, and appropriately reduced inlet pressure can produce a VARTM part with high fiber volume fraction and low void content.

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Uddin, Nasim, Uday Vaidya, Muhammad Shohel, and J. C. Serrano-Perez. "Cost-effective bridge girder strengthening using vacuum-assisted resin transfer molding (VARTM)." Advanced Composite Materials 13, no. 3-4 (January 2004): 255–81. http://dx.doi.org/10.1163/1568551042580163.

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Rubino, Felice, and Pierpaolo Carlone. "A Semi-Analytical Model to Predict Infusion Time and Reinforcement Thickness in VARTM and SCRIMP Processes." Polymers 11, no. 1 (December 24, 2018): 20. http://dx.doi.org/10.3390/polym11010020.

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In liquid composite molding processes, such as resin transfer molding (RTM) and vacuum assisted resin transfer molding (VARTM), the resin is drawn through fiber preforms in a closed mold by an induced pressure gradient. Unlike the RTM, where a rigid mold is employed, in VARTM, a flexible bag is commonly used as the upper-half mold. In this case, fabric deformation can take place during the impregnation process as the resin pressure inside the preform changes, resulting in continuous variations of reinforcement thickness, porosity, and permeability. The proper approach to simulate the resin flow, therefore, requires coupling deformation and pressure field making the process modeling more complex and computationally demanding. The present work proposes an efficient methodology to add the effects of the preform compaction on the resin flow when a deformable porous media is considered. The developed methodology was also applied in the case of Seeman’s Composite Resin Infusion Molding Process (SCRIMP). Numerical outcomes highlighted that preform compaction significantly affects the resin flow and the filling time. In particular, the more compliant the preform, the more time is required to complete the impregnation. On the other hand, in the case of SCRIMP, the results pointed out that the resin flow is mainly ruled by the high permeability network.

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Song, Jun Hee. "Manufacturing method of carbon and glass fabric composites with dispersed nanofibers using vacuum-assisted resin transfer molding." e-Polymers 14, no. 5 (September 1, 2014): 345–52. http://dx.doi.org/10.1515/epoly-2014-0091.

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AbstractFiber-reinforced composites have favorable structural characteristics such as their light weight, high specific strength, and high stiffness. Vacuum-assisted resin transfer molding (VARTM), used for manufacturing these composites, is relatively simple and provides materials with excellent mechanical properties. In this study, the author investigated the utility of VARTM in improving the performance of a carbon nanofiber (CNF)/carbon fiber composite impregnated with thermosetting resin. Processing parameters were determined, and the integrity of the manufactured composites was assessed. Carbon and glass fibers were used as reinforcing materials in an epoxy resin matrix. CNFs, which have excellent thermal and electrical characteristics, were dispersed in the composites. The pore sizes using the 0°/90°- and 90°/45° types of laminates were about 45 and 50 μm, respectively. The integrated composites produced had low porosity (below 3.7×10-5%).

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Song, Jun Hee. "Bending properties of carbon fiber nanocomposites with lamination structure of reinforcement." Journal of Polymer Engineering 36, no. 5 (July 1, 2016): 481–87. http://dx.doi.org/10.1515/polyeng-2015-0144.

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Abstract Advanced materials with excellent performance are in high demand in modern industry. Carbon fiber composites offer a number of advantageous mechanical properties. A significant improvement in fiber-reinforced composites can be achieved by dispersing a very small amount of nanofiller in the resin. Vacuum-assisted resin transfer molding (VARTM) is one of the most important processes for producing reinforced plastics. In this work, several composite samples were fabricated with the infusion of carbon nanofibers (CNFs) into the epoxy matrix using VARTM process. Using scanning electron microscopy (SEM), it was confirmed that CNFs were well dispersed in the resin. Bending tests were performed to investigate the mechanical properties of the samples, and SEM, to examine the fracture surfaces.

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Wang, Zhi Tao, Yong Kang Luo, Xing Ding, and Guo Fang Xi. "The Research on Flame Retardant Wind Turbines Nacelle Made through VARTM Process." Advanced Materials Research 450-451 (January 2012): 508–12. http://dx.doi.org/10.4028/www.scientific.net/amr.450-451.508.

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During the process of Vacuum Assisted Resin Transfer Molding（VARTM）making flame retardant wind turbines nacelle, the viscosity of unsaturated polyester resin（UPR）with reactive flame retardant groups is too large to be used in VARTM process. In this paper, a large amount of tests were conducted by the way of adding flame retardant of Dimethyl methyl phosphate(DMMP) so as to make the resin fit for VARTM processing properties requirements as well as increase its flame retardant properties to a higher level. The results showed that, when the content of DMMP was 12%, the resin could be provided with lower viscosity with a reduction of 50.3%, making it possible for the resin to be used in vacuum import process. When the content of DMMP reached 12%, LOI of the casting body reached 31.6, with LOI of glass fiber reinforced plastic of 37.0%, the vertical burning classification of which reached V-0 level without significant drop on mechanical properties of fiberglass reinforced plastics(GFRP). Meet the requirements and provide a good material for flame-retardant wind turbines nacelle.

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Chang, Chih-Yuan. "Modeling and evaluation of the filling process of vacuum-assisted compression resin transfer molding." Journal of Polymer Engineering 33, no. 3 (May 1, 2013): 211–19. http://dx.doi.org/10.1515/polyeng-2012-0160.

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Abstract In the present study, a modified vacuum-assisted compression resin transfer molding (VACRTM) process has been developed to reduce the cycling period. The process uses an elastic bag placed between the upper mold and the preform to replace the mobile rigid mold in compression resin transfer molding. During resin injection, the bag is pulled upward by the vacuum applied in between the upper mold and the bag, and a loose fiber stack is then present. Resin is easily injected into the mold. Once enough volume of resin is injected, the compression pressure is applied on the bag, which compacts the preform and drives the resin through the remaining dry preform. Numerical results show that the bag compression phase is much longer than the resin injection one. A multistage compression strategy can be used to control the compression time. Due to inherent process defects, a higher volume of the injected liquid is essential and thus leads to a longer injection and compression phase in order to inject and squeeze the excess resin. The late compression is very slow in draining the residual resin. As compared with resin transfer molding, VACRTM can reduce the mold-filling time/injection pressure.

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Dai, J., D. Pellaton, and H. T. Hahn. "A comparative study of vacuum-assisted resin transfer molding (VARTM) for sandwich panels." Polymer Composites 24, no. 6 (December 2003): 672–85. http://dx.doi.org/10.1002/pc.10061.

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Grujicic, M., K. M. Chittajallu, and Shawn Walsh. "Non-isothermal preform infiltration during the vacuum-assisted resin transfer molding (VARTM) process." Applied Surface Science 245, no. 1-4 (May 2005): 51–64. http://dx.doi.org/10.1016/j.apsusc.2004.09.123.

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WOODS, B. K. S., N. WERELEY, R. HOFFMASTER, and N. NERSESSIAN. "MANUFACTURE OF BULK MAGNETORHEOLOGICAL ELASTOMERS USING VACUUM ASSISTED RESIN TRANSFER MOLDING." International Journal of Modern Physics B 21, no. 28n29 (November 10, 2007): 5010–17. http://dx.doi.org/10.1142/s0217979207045967.

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Magnetorheological elastomers (MREs) consist of ferromagnetic particles embedded in a compliant matrix (i.e. elastomer). Due to the magnetic interaction of the ferromagnetic particles, MREs exhibit field dependent physical properties. Very significant changes in the modulus and loss factor of the elastomer can be realized. This makes MREs a promising candidate for active vibration control mechanisms. One factor currently limiting the implementation of this technology is the lack of an efficient manufacturing method that is practical for mass production. Most of the specimens created for previous MRE research were made using simple casting or mechanical mixing methods that are not ideal. In this research a new methodology for producing MREs using Vacuum Assisted Resin Transfer Molding (VARTM) was investigated. The method was used with a range of iron particles sizes and silicon elastomer systems and found to be effective within certain limits of applicability. The specimens produced were tested in compression under a range of magnetic fields to validate the presence of the MR effect. Relative changes in compressive modulus ranging from 35% to 150% (depending on volume fraction), under fields of around 0.3T were observed.

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Johnson, R. J., and R. Pitchumani. "Active Control of Reactive Resin Flow in a Vacuum Assisted Resin Transfer Molding (VARTM) Process." Journal of Composite Materials 42, no. 12 (June 2008): 1205–29. http://dx.doi.org/10.1177/0021998308091264.

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Wu, Da, Ragnar Larsson, and Mohammad S. Rouhi. "Modeling and Experimental Validation of the VARTM Process for Thin-Walled Preforms." Polymers 11, no. 12 (December 3, 2019): 2003. http://dx.doi.org/10.3390/polym11122003.

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In this paper, recent shell model is advanced towards the calibration and validation of the Vacuum-assisted Resin Transfer Molding (VARTM) process in a novel way. The model solves the nonlinear and strongly coupled resin flow and preform deformation when the 3-D flow and stress problem is simplified to a corresponding 2-D problem. In this way, the computational efficiency is enhanced dramatically, which allows for simulations of the VARTM process of large scale thin-walled structures. The main novelty is that the assumptions of the neglected through-thickness flow and the restricted preform deformation along the normal of preform surface suffice well for the thin-walled VARTM process. The model shows excellent agreement with the VARTM process experiment. With good accuracy and high computational efficiency, the shell model provides an insight into the simulation-based optimization of the VARTM process. It can be applied to either determine locations of the gate and vents or optimize process parameters to reduce the deformation.

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Chang, Chih-Yuan. "Experimental analysis of resin infusion in air cushion method." Journal of Polymer Engineering 36, no. 9 (November 1, 2016): 949–56. http://dx.doi.org/10.1515/polyeng-2015-0346.

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Abstract A new technique of resin infusion, called the air cushion method (ACM), has been developed to improve infusion time associated with the vacuum assisted resin transfer molding (VARTM) process. The method utilizes an innovative vacuum bag consisting of a bagging film and air cushions. After the preform is sealed by the bagging film and then evacuated, distribution channels are created between air cushions for flow enhancement during infusion. Once the required volume of resin is infused, the bonding interfaces between the air cushion and the bagging film are punctured and distribution channels collapse. The ambient pressure is applied on the bagging film that entirely compacts the preform. This paper investigates the infusion process in ACM using flow visualization experiments. An approximate estimation of the equivalent permeability of the bulk distribution channel is provided. Finally, an assessment of the properties of the ACM part is performed in comparison with VARTM part.

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Archodoulaki, Vasiliki Maria, Massimiliano Merola, Dimitrios Kastanis, Thomas Koch, and Pierpaolo Carlone. "Influence of the Impregnation Velocity on Impregnation Quality and Mechanical Properties of Vacuum Assisted Resin Transfer Moulding (VARTM) Materials." Materials Science Forum 825-826 (July 2015): 36–43. http://dx.doi.org/10.4028/www.scientific.net/msf.825-826.36.

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Vacuum Assisted Resin Transfer Molding (VARTM) fabricated FRP laminates generally show significantly small void contents. The apparent difference in void content is generally attributed to the difference in the resin infusion driving force, i.e., vacuum versus injection pressure. In the present study, we contrast the influence of processing parameters on the impregnation quality of FRP laminates. Application of different vacuum pressures (500, 800 and ~103 mbar) during VARTM results in different impregnation velocity due to different compaction levels produced. Composite laminates were realized using epoxy resin reinforced with carbon (CF) or glass continuous (GF) fibers. Two different textile architectures, namely unidirectional non-crimp fabrics (UD) and woven-mat (0/90), were used and various processing conditions were employed. Optical microscope observations revealed an unexpected trend relatively to the intra and inter bundle voids concentration with respect to the impregnation velocity, especially using UD-CF and UD-GF reinforcements and low impregnation rate. Tensile and three point bending tests highlighted the strong impact of fiber material and architecture on mechanical properties, whereas the presence of voids played a slight influence on the fiber dominated characteristics analyzed.

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Brahma, Siddhartha, Selvum Pillay, and Haibin Ning. "Comparison and characterization of discontinuous carbon fiber liquid-molded nylon to hydroentanglement/compression-molded composites." Journal of Thermoplastic Composite Materials 33, no. 8 (February 26, 2019): 1078–93. http://dx.doi.org/10.1177/0892705718817346.

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This article looks at liquid molding of polyamide 6 (PA6) via vacuum assisted resin transfer molding (VARTM) of discontinuous recycled carbon fiber composites. Its mechanical, thermal, and optical characterization is compared to hydroentanglement/compression molding. Liquid-molded composites show consistent improvement in their tensile and impact properties at three different weight fractions in comparison to hydroentanglement/compression molding. There was roughly a 10 and 13% increase in its tensile strength, modulus, and impact strength properties at 30 and 40% weight fractions and almost a 120% increase at 50% weight fraction. Fourier-transform infrared spectroscopy and differential scanning calorimetry data show that the caprolactam was synthesized to PA6 and was comparable to commercial grade PA6 used in this research. Scanning electron microscopy studies show poor wet out in the case of hydroentanglement/compression molding as compared to VARTM. The combination of better mechanical performance and lower processing temperature (165°C) shows promise in being a viable method to process PA6-based recycled fiber composites.

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Park, Hyun Bum. "Investigation on Mechanical Properties of Natural Fiber Composite Using RTM Manufacturing Method." Applied Mechanics and Materials 752-753 (April 2015): 473–76. http://dx.doi.org/10.4028/www.scientific.net/amm.752-753.473.

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In this study, an investigation on mechanical properties of flax/vinyl ester natural fiber composite was performed. Vacuum Assisted Resin Transfer Molding (VARTM) manufacturing method was adopted for manufacturing the flax fiber composite specimen. The mechanical properties of the manufactured flax composites were compared with flax composite data cited from some references. Based on this, the experimental data showed that the flax/vinyl ester composite has some advantages when it is applied to environment-friendly structure.

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Yoon, Myung-Keun, Joyce Baidoo, John W. Gillespie, and Dirk Heider. "Vacuum Assisted Resin Transfer Molding (VARTM) Process Incorporating Gravitational Effects: A Closed-form Solution." Journal of Composite Materials 39, no. 24 (June 14, 2005): 2227–42. http://dx.doi.org/10.1177/0021998305053510.

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Kong, Ling-Mei, Xiao-Bing Wang, Wei Zheng, Guang-Da Wu, Yan-Yan Qi, Ya-Juan Xue, and Bao-Chun Wang. "Mechanical Properties of Resin Reinforced Fiber-Ceramic-Fiber Composites Prepared by Vacuum Assisted Resin Transfer Molding." Science of Advanced Materials 12, no. 3 (March 1, 2020): 383–90. http://dx.doi.org/10.1166/sam.2020.3603.

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Ceramic-fiber composites have important applications in protection field. In this work, the stable and reliable resin reinforced fiber-ceramic-fiber (RRFCF) composites with sandwich structure were prepared by using the vacuum assisted resin transfer molding (VARTM) process. The mechanical properties of the prepared RRFCF composites with different configurations were studied. Results showed that the thickness values of the glassfiber-reinforced plastic layers (panel thickness: ta and backplane thickness: tc) had significant influences on the unique mechanical properties of the RRFCF composites. The stress distribution of RRFCF composites with different configurations under loading was analyzed by simulation. The fatigue behaviors of Z-type (ta < tc) and F-type (ta > tc) RRFCF composites were investigated and found to be in good agreement with the simulated results. Moreover, the flexural strength and modulus of Z-type composites were obtained and found to be higher than those of F-type composites. These results have important guiding significance for the engineering application of RRFCF composites.

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Khattab, Ahmed. "Cure Cycle Effect on High-Temperature Polymer Composite Structures Molded by VARTM." Journal of Composites 2013 (April 28, 2013): 1–6. http://dx.doi.org/10.1155/2013/162657.

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This paper presents an analytical and experimental investigation of cure cycle effect on carbon-fiber reinforced high-temperature polymer composite structures molded by vacuum assisted resin transfer molding (VARTM). The molded composite structure consists of AS4-8 harness carbon-fiber fabrics and a high-temperature polymer (Cycom 5250-4-RTM). Thermal and resin cure analysis is performed to model the cure cycle of the VARTM process. The temperature and cure variations with time are determined by solving the three-dimensional transient energy and species equations within the composite part. Several case studies were investigated by the developed analytical model. The same cases were also experimentally investigated to determine the ultimate tensile strength for each case. This study helps in developing a science based technology for the VARTM process for the understanding of the process behavior and the effect of the cure cycle on the properties of the molded high-temperature polymer composites.

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Amirkhosravi, Mehrad, Maya Pishvar, and M. Cengiz Altan. "Void reduction in VARTM composites by compaction of dry fiber preforms with stationary and moving magnets." Journal of Composite Materials 53, no. 6 (August 1, 2018): 769–82. http://dx.doi.org/10.1177/0021998318791311.

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Voids are the most common process-induced defects in composite laminates fabricated by vacuum assisted resin transfer molding (VARTM). Reduction or total elimination of these defects is essential for the improved performance and long-term durability of the structural composites. This study introduces a novel method that reduces the void content in VARTM laminates to below 1% by compacting the fibrous mat before infusion. The compaction is achieved by applying magnetic pressure on the vacuum bag by either stationary or moving magnets which are removed before the resin infusion. To assess the effectiveness of the proposed method, 6-, 12-, and 18-ply random mat glass/epoxy laminates are fabricated by VARTM using compacted and uncompacted mats and their properties are compared. In addition, different sets of magnets are used to investigate the effect of compaction levels on the resin flow and the quality of the final part. The placement of stationary magnets on the entire vacuum bag surface is practical for fabrication of small parts. For medium to large parts, however, magnets with a smaller footprint can be moved to apply the compaction pressure over a larger vacuum bag surface. The results show that by applying compaction pressure of 0.2 MPa or higher either by stationary or moving magnets on the dry preforms, the void volume fraction was decreased by 65%–95% to 0.1%–0.8% in all laminates.

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Louisy, Elodie, Fabienne Samyn, Serge Bourbigot, Gaëlle Fontaine, and Fanny Bonnet. "Preparation of Glass Fabric/Poly(l-lactide) Composites by Thermoplastic Resin Transfer Molding." Polymers 11, no. 2 (February 15, 2019): 339. http://dx.doi.org/10.3390/polym11020339.

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This study reports the first example of the production of polylactide composites prepared by Thermoplastic Resin Transfer Molding (T-RTM) via in situ bulk polymerization of l-lactide (l-LA) after injection in a closed mold containing glass fabrics. Tin octoate Sn(Oct)2 was used as the catalyst and first evaluated at the lab-scale in the experimental conditions required in the tank and in the mold of the RTM device. The reactions were then upscaled in the RTM in the absence of reinforcement to ensure the feasibility of the process (transfer and polymerization). Finally, poly-l-lactide (PLLA)-based composites with glass fabrics as the reinforcement were obtained. The resulting PLLA matrices exhibited conversions up to 99% along with high molar masses of up to 78,000 g·mol−1 when the polymerization was carried out under dynamic vacuum (vacuum-assisted RTM, VARTM). Moreover, a good impregnation of the glass fabrics by the matrix was observed by optical microscopy.

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Shankarachary, Bairoju, N. Sateesh, Lavu Gopinath, and Siripuram Aparna. "Effect of permeability on GFRP laminate produced by VARTM process." E3S Web of Conferences 184 (2020): 01029. http://dx.doi.org/10.1051/e3sconf/202018401029.

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Vacuum assisted resin transfer molding (VARTM) is one of the manufacturing technique that is viable for production of fiber reinforced polymer composite components suitable for aerospace, marine and commercial applications. However the repeatable quality of the product can be achieved by critically fixing the process parameters such as Vacuum Pressure (VP) and permeability of the preform. The present investigation is aimed at studying the effect of permeability for production of Glass Fiber Reinforced Polyester (GFRP) components with consistent quality. The VARTM mould is made with an acrylic transparent top cover to observe and record the resin flow pattern. Six layers of randomly placed glass fiber under five different vacuum pressures VP1 = 0.013, VP2 = 0.026, VP3 = 0.039, VP4 = 0.053 and VP5 = 0.066 MPa were studied. The laminates produced by this process under the above mentioned conditions were characterized with ASTM D procedures so as to study the effect of these process parameters on the quality of the laminate. And as mentioned there is a considerable effect of permeability on the impact strength and the void content in the laminates under different vacuum pressures. SEM analysis of the impact tested fractured GFRP composites showed the bonding of fiber and matrix.

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Shah, M., and V. Chaudhary. "Flow modeling and simulation study of vacuum assisted resin transfer molding (VARTM) process: A review." IOP Conference Series: Materials Science and Engineering 872 (June 27, 2020): 012087. http://dx.doi.org/10.1088/1757-899x/872/1/012087.

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McCaffery, Timothy R., Zachary Z. Zguris, and Yvon G. Durant. "Low Cost Mold Development for Prototype Parts Produced by Vacuum Assisted Resin Transfer Molding (VARTM)." Journal of Composite Materials 37, no. 10 (May 2003): 899–912. http://dx.doi.org/10.1177/0021998303037010003.

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Gou, Jihua, Scott O'Braint, Haichang Gu, and Gangbing Song. "Damping Augmentation of Nanocomposites Using Carbon Nanofiber Paper." Journal of Nanomaterials 2006 (2006): 1–7. http://dx.doi.org/10.1155/jnm/2006/32803.

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Vacuum-assisted resin transfer molding (VARTM) process was used to fabricate the nanocomposites through integrating carbon nanofiber paper into traditional glass fiber reinforced composites. The carbon nanofiber paper had a porous structure with highly entangled carbon nanofibers and short glass fibers. In this study, the carbon nanofiber paper was employed as an interlayer and surface layer of composite laminates to enhance the damping properties. Experiments conducted using the nanocomposite beam indicated up to 200–700% increase of the damping ratios at higher frequencies. The scanning electron microscopy (SEM) characterization of the carbon nanofiber paper and the nanocomposites was also conducted to investigate the impregnation of carbon nanofiber paper by the resin during the VARTM process and the mechanics of damping augmentation. The study showed a complete penetration of the resin through the carbon nanofiber paper. The connectivities between carbon nanofibers and short glass fibers within the carbon nanofiber paper were responsible for the significant energy dissipation in the nanocomposites during the damping tests.

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Ghose, Sayata, Kent A. Watson, Roberto J. Cano, Sean M. Britton, Brian J. Jensen, John W. Connell, Helen M. Herring, and Quentin J. Lineberry. "High Temperature VARTM of Phenylethynyl Terminated Imides." High Performance Polymers 21, no. 5 (September 8, 2009): 653–72. http://dx.doi.org/10.1177/0954008309339935.

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Depending on the part type and quantity, fabrication of composite structures using vacuum-assisted resin transfer molding (VARTM) can be more affordable than conventional autoclave techniques. Recent efforts have focused on adapting VARTM for the fabrication of high temperature composites. Due to their low melt viscosity and long melt stability, certain phenylethynyl terminated imides (PETI) can be processed into composites using high temperature VARTM (HT-VARTM). However, one of the disadvantages of the current HT-VARTM resin systems has been the high porosity of the resultant composites. For aerospace applications, the desired void fraction of less than 2% has not yet been achieved. In the current study, two PETI resins, LaRC PETI-330 and LaRC PETI-8 have been used to make test specimens using HT-VARTM. The resins were infused into ten layers of IM7-6K carbon fiber 5-harness satin fabric at 260 or 280 °C and cured at temperature up to 371 °C. Initial runs yielded composites with high void content, typically greater than 7% by weight. A thermogravimetric-mass spectroscopic study was conducted to determine the source of volatiles leading to high porosity. It was determined that under the thermal cycle used for laminate fabrication, the phenylethynyl endcap was undergoing degradation leading to volatile evolution. This finding was unexpected as high quality composite laminates have been fabricated under higher pressures using these resin systems. The amount of weight loss experienced during the thermal cycle was only about 1% by weight, but this led to a significant amount of volatiles in a closed system. By modifying the thermal cycle used in laminate fabrication, the void content was significantly reduced (typically ∼ 3% or less). The results of this work are presented herein.

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Hosur, M. V., U. K. Vaidya, A. Abraham, N. Jadhav, and S. Jeelani. "Static and High Strain Rate Compression Response of Thick Section Twill Weave S-2 Glass/Vinyl Ester Composites Manufactured by Affordable Liquid Molding Processes." Journal of Engineering Materials and Technology 121, no. 4 (October 1, 1999): 468–75. http://dx.doi.org/10.1115/1.2812403.

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Fiber reinforced composites, due to their higher specific strength and specific stiffness, are replacing many metallic structures. Of these, thick composite laminates are of high interest in various, millitary, transportation and marine applications for their use in ballistic and shock protection. One such application is in Composite Armored Vehicle (CAV) integral armor comprising of thick section composite that serves as the primary load-bearing component. The current solution of the structural backing laminate utilizes an S2-glass/epoxy system processed using automated fiber placement method. While proven structurally suitable, this method is time consuming as well as expensive. This paper presents several alternative cost-effective manufacturing solutions for fabricating composite laminates of 20 mm (0.8 in.) nominal thickness (made of 45 layer, 2 × 2 twill weave S2-glass with 933 sizing/vinyl ester C-50 resin), consisted with them CAV application in focus. They include Vacuum Assisted Resin Transfer Molding (VARTM) and Vacuum Assisted Resin Infusion Modeling (VARIM) and their variations. The effectiveness of different affordable processing approaches adopted in fabricating the structural laminate is compared in terms of static and dynamic compression response of the laminations. Static studies have been conducted on thick composites using specimen based on Army Material Technology Laboratory’s (AMTL) recommendation for thick section composites, while dynamic response is studied on cubic specimen samples using a Split Hopkinson Pressure Bar (SHPB).

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Yu, Tianyu, Yun-Hae Kim, and Soo-Jeong Park. "Comparison of different surface modifications on mechanical properties of HNTs incorporated CFRP for fine particle accumulation." Modern Physics Letters B 34, no. 07n09 (March 6, 2020): 2040006. http://dx.doi.org/10.1142/s0217984920400060.

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This paper presents an investigation into the effect of particle accumulation on an amorphous halloysite nanotube (A-HNT)/Carbon fiber reinforced plastic (CFRP) laminate, fabricated through Vacuum-assisted Resin Transfer Molding (VaRTM). Resin blending and Electrophoretic deposition (EPD) methods were impeded to incorporate the A-HNTs. Bending, short beam shear (SBS), and end-notched flexure (ENF) tests were individually conducted on three sections, which were divided from an integral CFRP laminate. The anchoring effect of the carbon fibers and the scouring effect of the resin flow together lead to the different A-HNT accumulation patterns in both incorporation methods, and thus caused the observed distinctions in the properties of each separated section. Extensively incorporated A-HNTs showed a tendency to aggregate, resulting in the degradation of the material’s properties.

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Mishra, Kunal, and Ranji Vaidyanathan. "The Influence of Nanoclay on the Flame Retardancy and Mechanical Performance of Recycled Carpet Composites." Recycling 4, no. 2 (June 3, 2019): 22. http://dx.doi.org/10.3390/recycling4020022.

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In the present study, we recycled waste carpet using a vacuum-assisted resin transfer molding (VARTM) process. Three different variations of carpet composites were fabricated, namely, neat epoxy, clay-coated, and clay-infused carpet composites. The carpet composite samples were degraded hygrothermally as well as under a cyclic UV condensation condition. Presence of clay was shown to impede the moisture absorption and UV degradation in the carpet composites. Flexural properties also showed that the presence of clay slows the degradation process of the composites. The flame retardancy result indicated that the presence of clay in the polymer network decreases the ignition time of the carpet composites.

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Peila, Roberta, J. C. Seferis, T. Karaki, and G. Parker. "Effects of nanoclay on the thermal and rheological properties of a vartm (vacuum assisted resin transfer molding) epoxy resin." Journal of Thermal Analysis and Calorimetry 96, no. 2 (November 11, 2008): 587–92. http://dx.doi.org/10.1007/s10973-008-9343-1.

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Khan, Muhammad Azhar Ali. "In-Plane Permeability Measurement of Biaxial Woven Fabrics by 2D-Radial Flow Method." Science and Engineering of Composite Materials 28, no. 1 (January 1, 2021): 153–59. http://dx.doi.org/10.1515/secm-2021-0014.

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AbstractThe accurate characterization of fabrics used in vacuum assisted resin transfer molding (VARTM) is essential in order to model the flow through these porous preforms. A wide range of these fabrics are available for composite manufacturing through VARTM and thus brings about a need to opt a methodology which characterizes the in-plane permeability of these preforms. These permeability values can then be used in simulations that can track the flow front progression and mold filling time. This work identifies the permeability of an E-glass fabric based on Darcy's law. Woven fabric having areal weight of 200 grams per square meter (gsm) is under consideration. The experiments are conducted at constant pressure conditions using 2D Radial flow method. Stereo microscopy of the preform material is done for detailed study of the weaving pattern. It is concluded that plain woven fabric exhibits anisotropic behavior when tested for in-plane permeability. Permeability is found to be higher in a direction which offers more interspacing between adjacent fibers threads causing more resin to flow in this direction.

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Dhimole, Vivek Kumar, Pruthvi Serrao, and Chongdu Cho. "Review and Suggestion of Failure Theories in Voids Scenario for VARTM Processed Composite Materials." Polymers 13, no. 6 (March 22, 2021): 969. http://dx.doi.org/10.3390/polym13060969.

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Fiber-reinforced composite structures are used in different applications due to their excellent strength to weight ratio. Due to cost and tool handling issues in conventional manufacturing processes, like resin transfer molding (RTM) and autoclave, vacuum-assisted resin transfer molding (VARTM) is the best choice among industries. VARTM is highly productive and cheap. However, the VARTM process produces complex, lightweight, and bulky structures, suitable for mass and cost-effective production, but the presence of voids and fiber misalignment in the final processed composite influences its strength. Voids are the primary defects, and they cannot be eliminated completely, so a design without considering void defects will entail unreliability. Many conventional failure theories were used for composite design but did not consider the effect of voids defects, thus creating misleading failure characteristics. Due to voids, stress and strain uncertainty affects failure mechanisms, such as microcrack, delamination, and fracture. That’s why a proper selection and understanding of failure theories is necessary. This review discusses previous conventional failure theories followed by work considering the void’s effect. Based on the review, a few prominent theories were suggested to estimate composite strength in the void scenario because they consider the effect of the voids through crack density, crack, or void modeling. These suggested theories were based on damage mechanics (discrete damage mechanics), fracture mechanics (virtual crack closure technique), and micromechanics (representative volume element). The suggested theories are well-established in finite element modeling (FEM), representing an effective time and money-saving tool in design strategy, with better early estimation to enhance current design practices’ effectiveness for composites. This paper gives an insight into choosing the failure theories for composites in the presence of voids, which are present in higher percentages in mass production and less-costly processes (VARTM).

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Lyu, Lihua, Liming Zhu, Jingrui Cui, Jing Guo, and Fang Ye. "Bending Property of Honeycombed 3D Woven Composites with Quadrilateral Cross Section." AATCC Journal of Research 7, no. 2 (March 1, 2020): 7–12. http://dx.doi.org/10.14504/ajr.7.2.2.

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The delamination resistance and damage tolerance of traditional honeycomb composites are poor. To overcome these defects, 3D (three-dimensional) integrated woven composites of honeycomb structure were designed, and then manufactured using the vacuum assisted resin transfer molding process (VARTM), based on the 3D self-prepared fabrics used as reinforcements. The load-displacement curves, maximum bending load-velocity curves, and bar chart of energy absorption were determined experimentally and calculated by finite element simulation. The results showed good agreement between experimental and finite element simulation data. The correctness of the model was verified, so the model can be used to predict the mechanical properties of 3D integrated woven composites of honeycomb structure with quadrilateral cross section.

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Journal articles on the topic 'Vacuum assisted resin transfer molding (VARTM)'

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