• Composites Research
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• 제28권6호
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• pp.402-407
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• 2015

It is well known that the polymer matrix composite materials have good specific strength, making them appropriate for use in transport vehicle. Since the property of composite materials can be obtained only after manufacturing parts, the property depends on greatly on the fabrication process, which is different from metallic system. Therefore, in order to use composite materials for aircraft, the certifying agency requires a robust database with extensive tests and proof of the process unlike metals. Recently developed material qualification methodology by NCAMP (National Center for Advanced Materials Performance) has been accepted by FAA and EASA and can be applied to type certificate reducing time and cost of developing a composite materials database for aircraft application. This paper summarizes a study to establish the composite materials database to apply the NCAMP methodology to composite materials characterization for composite aircraft and to provide the effective materials database through Aerospace Composite Materials Data Center to be approved by Korea Civil Aviation Certification Agency.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 춘계학술대회 논문집
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• pp.309-314
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• 2004

This study focused on the introduction of damage repair for polymeric composite carbody. called selfing tech-healinique. using microcapsules loaded with the healing agent The manufacturing process for microcapsules with the healing agent was introduced and tile characteristics of microcapsules manufactured by varying with various manufacturing process variables were evaluated. The DCPD was used for the healing agent and microcapsules were made of urea-formaldehyde resin. The magnitude and the size distribution of microcapsules were measured by a particle size analyzer using laser diffraction technique. Thermal stability was investigated by using a TGA under continuous and isothermal heating conditions for the healing agent. microcapsules without the healing agent. microcapsules with the healing agent.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2002년도 추계학술발표대회 논문집
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• pp.193-197
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• 2002

Polyurethane casting wing fairings included in F-5E/F 15% spar kit are to be installed on aircraft wing surfaces and used for compensating the changes of the aerodynamic configuration by the leading edge extension fairings. These fairing are mandatory items in repairing wing areas and was imported from foreign supplier with long term delivery and high cost. Accordingly, local manufacturing is necessary to get rid of above disadvantages such as long term delivery and high cost. Basic properties test of specimen to be developed and part's requirements after localization was taken and its values were similar or higher when comparing with the original's even in low temp test at -55C. Casting mold process was used to manufacture the polyurethane fairings and its demensional stability ＆ physical condition was proper and met to the related specification and drawing's requirements

• 한국기계가공학회지
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• 제14권3호
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• pp.85-91
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• 2015

The press-fit shaft is an important part used in automobiles, vessels, and trains. This study proposes an optimized design method to reduce damage that may occur in the press-fitted shaft by modifying the shape of the boss step of the press-fitted shaft. To reduce the time and cost of running the optimized design method, an approximate design optimization is applied and an optimized algorithm is generated using a genetic algorithm that is widely used in engineering fields and an approximate model using a response surface method. The planned experiments for the data that are needed to generate the approximate model use a central composite design (CCD) and Latin hypercube sampling (LHS), and the results of the approximate optimization using the above two design of experiments are to be compared.

• 한국기계가공학회지
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• 제16권3호
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• pp.30-37
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• 2017

When a wheel profile of a train-tram is designed, both train and tram tracks should be considered. This study designed a wheel profile that enables high-speed driving(200km/h) on the train track and low speed driving on the tram track with multiple sharp curves. The study used the approximation optimization method to reduce cost and time, used the sequential quadratic programming method as the optimized algorithm, and the central composite design and response surface method as an approximate model. The optimized wheel shape based on this approximation optimization method reduced wear of the initial wheel showed a better performance in terms of derailment and lateral force.

• 한국기계가공학회지
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• 제11권4호
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• pp.138-146
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• 2012

This research is to analyze the wave propagation characteristics of anisotropic materials subjected to the low-velocity impact. For this purpose, a higher-order finite element program is used to simulate the dynamic behaviors according to the changes of material property, stacking sequence and dimension etc.. Materials for simulation are composed of $[0^{\circ}]_{10s}$, $[45^{\circ}/-45^{\circ}]_{5s}$ and $[90^{\circ}]_{10s}$ stacking sequences. Finally, the results of this simulation are compared with those of wave propagation theory and then the impact responses and wave propagation phenomena are investigated.

• Composites Research
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• 제26권3호
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• pp.155-159
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• 2013

연속 섬유의 펼침에 대한 기술 현황 및 이의 적용에 대해 본 연구에서 정리되었다. 이론적 접근을 통해 연속 섬유 펼침의 효과를 소개하였고, 섬유 펼침 수단과 섬유 펼침 장치의 공정 상 위치를 기준으로 연속 섬유의 펼침에 대한 기술을 분류 정리하였다. 또한, 각 기술의 일반적인 섬유 펼침 원리, 기술적용 및 기술의 장 단점에 대해 소개하였으며, 향후 연속 섬유의 펼침에 대한 기술 연구 방향에 대해서도 고려되었다.

• 한국기계가공학회지
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• 제10권6호
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• pp.140-145
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• 2011

An anisotropic beam model is proposed by employing an asymptotic expansion method for thermo-mechanical multiphysics environment. An asymptotic method based on virtual work is introduced first, and then the variables of mechanical displacement and temperature rise are asymptotically expanded by taking advantage of geometrical slenderness of elastic bodies. Subsequently substituting these expansions into the virtual work principle allows us to asymptotically expand the virtual work. This will yield a set of recursive virtual works from which two-dimensional microscopic and one-dimensional macroscopic equations are systematically derived at each order. In this way, homogenized stiffnesses and thermomechanical coupling coefficients are derived. To demonstrate the validity and efficiency of the proposed approach, composite beams are taken as a test-bed example. The results obtained herein are compared to those of three-dimensional finite element analysis.

• 한국기계가공학회지
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• 제20권12호
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• pp.78-84
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• 2021

Reducing the weight of automobiles is a significant global developmental task. Two materials are used to lighten automobiles: aluminum and CFRP frames. Aluminum is a non-ferrous metal, and CFRP is a composite material. They are lighter and harder than other materials. The two materials were used for the collision analysis. Subsequently, the two cases were compared. Three cases were considered for the collision analysis: head-on collision, partial head-on collision, and side collision at a speed of 60 km/h. The three cases were compared and analyzed considering the materials used to understand the difference between aluminum and CFRP and their collision characteristics.

• 한국기계가공학회지
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• 제17권6호
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• pp.164-169
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• 2018

In this study, we solved the human hazard problem of aluminum liner by applying plastic PET liner which is widely used as a material for food and beverage containers in the market. In order to reinforce dome area by using low strength / high elongation plastic liner, The aluminum boss was covered on the plastic liner surface. In order to predict the performance of the developed product, the structural analysis was carried out by applying the three - dimensional laminated solid element, and the soundness of the product was verified through the prototype performance test.