• Journal of Aerospace System Engineering
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• v.13 no.1
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• pp.69-76
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• 2019

In this study, resin flow analysis of resin transfer moulding (RTM) method was performed for mould design of composite structure. The target composite structure was a tank used for fluid storage. Natural c fiber composite was adopted for composite structural design of the fluid storage tank. RTM was adopted for manufacturing of the tank using natural fiber composites. Resin flow analysis was performed to find the proper RTM conditions of the tank. The resin flow analysis was performed using the commercial FEM flow simulation software. After repeated analysis while changing the location of resin inlet and outlet, the proper resin filling time and pattern were found.

• Proceedings of the Korean Fiber Society Conference
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• 2001.04a
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• pp.217-220
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• 2001

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.6
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• pp.81-86
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• 2017

The high-pressure resin transfer molding (HP-RTM) process has a very effective for the mass production of carbon fiber reinforced plastic (CFRP) for light weight in the automotive industry. In developing robust equipment, new process and fast cure matrix systems reduces significantly the cycle time less than 5 minutes in recent years. This paper describes the cavity pressure, temperature and molding characteristics of the HP-RTM process. The HP-RTM mold was equipped with two cavity pressure sensors and three temperature sensors. The cavity pressure characteristics of the HP-RTM injection, pressurization, and curing processes were studied. This experiment was conducted with selected process parameters such as mold cap size, maximum press force, and injection volume. Consequently, this monitoring method provides correlations between the selected process parameters and final forming characteristics in this work.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.5
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• pp.157-165
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• 2017

The high-pressure resin transfer molding (HP-RTM) technology has been commercialized for fast production of fiber reinforced composite materials. The high-pressure mixing head was one of the most core component of the HP-RTM process. In this study, a mixing head was systematically designed, manufactured and evaluated. This mixing head was composed of a nozzle, a mixing chamber, a cleaning piston part, and an internal mold release part. In actual, a straight-type structure was newly designed instead of the conventional L-type structure for improving the maximum mixing pressure and mixing ratio precision. The performance of mixing head was showed maximum mixing pressure of 15.22MPa and mixing ratio precision of 0.12%. CFRP molding experiments were successfully obtained a 6~11 laminating carbon sheet using HP-RTM presses and specimen molds.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2001.05a
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• pp.176-179
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• 2001

When the preform is composed of more than two layers with different in-plane permeability in resin transfer molding, effective average permeability should be determined for the flow analysis in the mold. The most frequently used averaging scheme is the weighted average scheme, but it does not account for the transverse flow between adjacent layers. A new averaging scheme is proposed predicting the effective permeability of the multi-layered preform, which accounts for the transverse flow effect. The new scheme is verified by measuring the effective permeability of the multi-layered preforms and the difference in each flow front position.

• Journal of the Korean Society for Railway
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• v.18 no.4
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• pp.301-308
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• 2015

To reduce the weight of a railroad vehicle, a bogie frame skin is considered for manufacture using an RTM process and composite material. Compared to other processes, RTM has merits in that it demands only simple manufacturing facilities and can produce a large and complex structure in a short cycle time. On the other hand, it is important to determine the proper number and locations of gates and vents to prevent void formation inside a structure. In this study, we numerically predicted the flow pattern in a bogie frame skin during the RTM process by distinguishing the permeability of a fiber mat as isotropic or anisotropic. Using the results, we analyzed the RTM process conditions of the bogie frame to predict skin void formation, mold filling time, and optimum location of vents depending on the permeability conditions.

• Composites Research
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• v.17 no.3
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• pp.1-7
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• 2004

In the vacuum assisted RTM (VARTM) process that has become the center of attention for manufacturing massive composite structures, a good evacuation of air in the fiber preform is recognized as the prime factor. The microvoids, or the dry spots, are formed as a result of improper gate/vent locations and the mold geometry. The non-uniform resin velocity at the flow front leads to the formation of microvoids in the fibers, whereas the air in the microvoids can migrate along with the resin flow during mold filling. The residual air in the internal voids of a composite structure may cause a degradation of the mechanical properties as well as the structural failure. In this study, a unified macro- and micro analysis methods were developed to investigate the formation and transport of air in resin during VARTM process. A numerical simulation program was developed to analyze the three-dimensional flow pattern as well as the macro- and microscopic distribution of air in a composite part fabricated by VARTM process.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.983-988
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• 2004

In the present study, the effects of orthogonal ribs on structural warpage during injection molding process were investigated. Basic ribbed models for the evaluation of degree of warpage were introduced and designed. Injection molds for these models are manufactured based on the full 3D CAD/CAM technology and specimens are prepared for experiment. Numerical analysis using commercial plastic injection molding analysis software was also performed to compare the results with experimental ones. The variations of materials and parameters such as injection time, mold temperature, melt temperature, holding time were considered in the present work. It was shown that orthogonal ribs have significant effect on the reduction of warpage during the injection molding process.

• Composites Research
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• v.30 no.3
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• pp.202-208
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• 2017

Resin transfer molding (RTM) is a mass production process that allows the fabrication of composites ranging in size from small to large. Recently, fast curing resins with a curing time of less than about 10 minutes have been used in the automotive and aerospace industries. The viscosity of resin is bound up with the degree of cure, and it can be changed rapidly in the fast-cure resin system during the mold filling process. Therefore, it is advantageous to experimentally measure and evaluate the degree of cure because it requires much effort to predict the flow characteristics and cure of the fast curing resin. DMA and dielectric technique are the typical methods to measure the degree of cure of composite materials. In this paper, the resin flow and degree of cure were measured through the multi-channel dielectric system. A total of 8 channels of dielectric sensors were used and resin flow and degree of cure were measured and compared with each other under various pressure conditions.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.10a
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• pp.65-67
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• 2002

Resin Transfer Molding(RTM) is increasingly used for producing fiber reinforced polymer composites, the resin has to flow a long distance to impregnate the dry fibers. The measure for the resistance of the fiber preform to the resin flow is the permeability of the fiber preform. Permeability is a key issue in the design of molds and processes and in flow modeling. In this study, permeability measurement for braided preform is presented and compared with the permeability calculated numerically. Experimental techniques being used to measure the permeability are also discussed. Measurement is conducted in radial flow test under constant pressure.