• Design & Manufacturing
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• 제17권3호
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• pp.28-33
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• 2023

The conventional FRP (Fiber Reinforced Plastic) manufacturing process used thermoset resins for ease of molding but faced the issue of non-recyclability. To address these shortcomings, a new process utilizing thermal plastic resin was developed. However, due to the high viscosity of thermal plastic resin, problems such as fiber deformation and a reduced fiber volume fraction occurred during the high-temperature, high-pressure process. In this study, to overcome the limitations of the conventional process, fiber-reinforced composite materials were manufactured through in-situ polymerization using PLA (Poly L-Lactide) resin in the VA-RTM (Vacuum Assistance Resin Transfer Molding) process. The fiber volume of the produced specimens was calculated, and resin impregnation and porosity were confirmed through optical microscopy. Additionally, molecular weight analysis using GPC (Gel Permission Chromatography) demonstrated improvements over the conventional process and emphasized the essential requirement of temperature control.

• 한국생산제조학회지
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• 제23권2호
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• pp.145-151
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• 2014

Recently, the growing demand for weight reduction and improved structure durabilityfor commercial vehicles has led to active research into the development and application of suitablecomposite materials. This studysuggests abimaterial composite frame produced by apultrusion process to replace steel frames. We focused on the development of a composite frameconsisting of two types of materialsby mixing anorthotropic material with anisotropic material. The inside layer consisted of an aluminum pipe, and the outside layer was composed of a glass fiber pipe. To determine the strength and failure mechanisms of the composite material, tensile tests, shear tests, and three-point bending tests were conducted, followed by fatigue tests. After static testing, the fatigue tests were conducted at a load frequency of 5 Hz, a stress ratio (R) of 0.1, and an endurance limit of $10^6$ for the S-N curve. The resultsshowed that the failure modes were related to both the core design and the laminating conditions.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2000년도 추계학술발표대회 논문집
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• pp.253-256
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• 2000

In order to commercialize the low cost composite fabrication technology in the area of domestic aerospace structure field, Resin Transfer Molding process has been considered as an alternative process to replace the high cost autoclave technology. The end part for the development of RTM process is the control rod of flight control system of aircraft. A braided preform was triaxially designed to improve the dimensional stability and mechanical property in the direction of external loads. Through the flow analysis using CVFEM, the resin filling time was calculated and the resin injection method was determined. The results of the flow analysis were directly applied to RTM mold design. The control rod was successfully manufactured by RTM process using internal pressure. The length and outer diameter of the manufactured part are 1148mm and 32mm, respectively.

• 한국생산제조학회지
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• 제7권1호
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• pp.34-40
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• 1998

Conductive metal matrix composite(MMC) material of 30% silicon carbide particulated based on aluminum matrix was machined by die sinking electrical discharge machining(EDM) process according to different current and duty factor for reverse polarity of electrode. Material removal rate(MRR) was examined by process under various operation conditions. The surface morphology was evaluated by surface roughness parameter and scanning electron microscopy(SEM) research. The MRR was suddenly increased over 11 ampere of current, and it was slightly changed over 0.3 of duty factor. The maximum surface roughness of EDMed surface was affected by the duty factor. The SEM photograghs of EDMed surface showed wide recast distribution region of melting materials as increased of current and duty factor.

• 한국기계가공학회지
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• 제15권1호
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• pp.50-60
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• 2016

Laminate composites have a number of excellent characteristics in aspects of strength, stiffness, bending, and buckling. Buckling and postbuckling analysis of laminate composites with layups of [90/0]2s, $[{\pm}45/90/0]s$, $[{\pm}45]2s$ has been carried using the Total Lagrangian nonlinear Newton-Raphson method. The formulation of a geometrically nonlinear composite shell element based on a nonlinear large deformation method is presented. The used element is an eight-node degenerated shell element with six degrees of freedom. Square, circular cylinder, and arch panel laminate geometries were analyzed to verify the effects of the layups on the buckling and postbuckling behavior. The results showed that the effects of laminate layups on bucking and postbuckling behavior and the present formulation showed very good agreement with existing references.

• 한국기계가공학회지
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• 제10권1호
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• pp.47-53
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• 2011

From recent research, it has revealed that Electroacitve polymer(EAP) has a physical limitation. Carbon nanotube(CNT) is known as the promising material which has excellent electro-mechanical characteristics and is mostly defect-free. It is expected that a successful synthesis of CNT and Nafion known as a primary material for IPMC would make a great improvement on its electro-mechanic feature. In this paper, we suggest the method of synthesis of CNT with Nafion which improves electro-mechanical characteristic. Using mechanical dispersion with Nafion and Isopropyl Alcohol(IPA), we disperse Single-walled carbon nanotubes(SWCNT). For a uniformly layer of CNT, we used a spray gun on a hot plate by a simplified method. In the result, we fabricated a disperse SWCNT/Nafion composite uniformly.

• 한국기계가공학회지
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• 제12권3호
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• pp.81-88
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• 2013

Recently, energy-saving technology is rapidly becoming a crucial issue for mankind due to the depletion of natural resources. From this perspective, every automobile manufactures are trying to develop light materials and to validate safety with environmental consideration. In this study, we developed clutch connector tube which is the parts of power transferring clutch with light materials to substitude for existing general steel materials. We also verified that the general steel materials can be replaced with nylon, fiberglass, stainless and plastic materials or not. As a result, we verified that the mixture of glass and nylon composite material can substitude the general steel.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2003년도 추계학술발표대회 논문집
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• pp.225-230
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• 2003

Domestic small and medium ship companies have lack of leisure boat technologies and especially they have a problem about its low performance because of the overweight of boat hull. So it is necessary to have alternative manufacturing process to improve the mechanical properties of composite material. In this study, a vacuum curing system was developed as an alternative manufacturing process and then changed the fiber volume fractions of GFRP laminates. The properties of GFRP laminates such as void contents, Young's modulus and fracture toughness were determined for various fiber volume fractions.

• 한국기계가공학회지
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• 제19권2호
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• pp.75-80
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• 2020

In this study, we designed car frames for collision analysis using carbon fiber reinforced polymer (CFRP) as the lighter composite material. The impact conditions were 100 percent frontal impact, 40 percent frontal impact, and 90 degrees side impact. The impact analysis measured the maximum stress at velocities of 20km/h and 40km/h for each condition and evaluated the vulnerable points in the car frame. Additional supports have been designed both to improve the weak points in existing vehicle frames, and to be taken into account when new parts are assembled. Our impact analysis compared the results of maximum stress on the car frame with and without the support.

• 한국기계가공학회지
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• 제2권2호
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• pp.37-44
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• 2003

Composite materials are widely used to make all kinds of machine parts, internal and structural materials of cars, aerospace industries, building structures, ship materials, sporting goods and others. It is worth the while to use composite materials as various substitutions when compared With others. But the use is limited in the field of the mechanical processing because of its difficulties in cutting. The surface roughness of in and out in the hole processing was discussed after cutting the GFRP with HSS drill in the vertical machining center. And it is observed that as it processed more, the powdered chip may be got more than the fluid type long chip.