• 한국재료학회지
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• 제29권1호
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• pp.43-51
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• 2019

Nacre of abalone shell features a "brick-and-mortar" microstructure, in which micro-plates of calcium carbonate are bonded by nanometers-thick layers of chitin and proteins. Due to the microstructure and its unique toughening mechanisms, nacre possesses an excellent combination of specific strength, stiffness and toughness. This study deals with the possibility of using nacre fragments obtained from abalone shell for making a bulletproof armor system. A composite plate laminated with abalone shell fragments is made and compression and bend tests are carried out. In addition, a bulletproof test is performed with hybrid armor systems which are composed of an alumina plate, a composite plate, and aramid woven fabric to verify the ballistic performance of nacre. The compressive strength of the composite plate is around 258.3 MPa. The bend strength and modulus of the composite plate decrease according to the plate thickness and are about 149.2 MPa and 50.3 GPa, respectively, for a 4.85 mm thick plate. The hybrid armor system with a planar density of $45.2kg/m^2$, which is composed of an 8 mm thick alumina plate, a 2.4 mm thick composite plate, and 18 layers of aramid woven fabric, satisfy the NIJ Standard 0101.06 : 2008 Armor Type IV. These results show that a composite plate laminated with abalone shell fragments can be used for a bulletproof armor system as an interlayer between ceramic and fabric to decrease the armor system's weight.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2008년도 정기 학술대회
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• pp.276-281
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• 2008

Glass-fiber reinforced polyester(GFRP) composite material is a promising alternative to existing construction materials such as steel, concrete and wood. One of passible applications of GFRP composite material is to build temporary bridges by assembling GFRP composite decks. In this paper, we develop a system of temporary arch bridges that can be built by easy assembling of GFRP composite decks. For this purpose, several types of temporary arch bridges are suggested and verified by FE analysis.

• International Journal of Aerospace System Engineering
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• 제4권1호
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• pp.9-12
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• 2017

In this study, an investigation on mechanical properties of flax natural fiber composite is performed as a precedent study on the design of eco-friendly structure using flax natural fiber composite. The Vacuum Assisted Resin Transfer Molding-Light (VARTML) manufacturing method is adopted for manufacturing the flax fiber composite panel. The VARTML is a manufacturing process that the resin is injected into the dry layered-up fibers enclosed by a rigid mold tool under vacuum. In this work, the resin flow analysis of VARTM manufacturing method is performed. A series of flax composite panels are manufactured, and several kinds of specimens cut out from the panels are tested to obtain mechanical performance data. Based on this, structural design of chemical storage tank for agricultural vehicle was performed using flax/vinyl ester. After structural design and analysis, the resin flow analysis of VARTM manufacturing method was performed.

• Transactions on Electrical and Electronic Materials
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• 제16권6호
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• pp.338-341
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• 2015

Epoxy/micro-sized alumina composite was prepared, and the effects of alumina content on the dielectric properties were investigated in order to develop an insulation material for gas-insulated switchgears (GIS). Nano-sized alumina (average particle size: 30 nm) was also incorporated into the epoxy/micro-sized alumina composite. Dielectric tests were carried out in ASTM D 150, and capacitance (Cp) and dielectric loss (tanδ) were measured. The dielectric constant increased with increasing alumina content in the epoxy/micro-alumina system and the epoxy/micro-alumina/nano-alumina system. As 1,3-diglycidyl glyceryl ether (DGE) content increased, the dielectric constant decreased and dielectric loss increased. This ocurred as a result of the weak electric field enhancement due to homogeneous dispersion of micro- and nano-sized alumina particles in an epoxy composite.

• KIEAE Journal
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• 제8권1호
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• pp.93-98
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• 2008

As high rise buildings and large span spatial structures are constructed, new composite members and construction techniques are continuously developed. Wide flange steel beam can be easily constructed but the fire proofing protection is necessary and the cost is high. Nowadays environmental pollution of structures is becoming a big issue. The material of fire proofing protection is not allowed to use for structural members in several countries because it cab be a cause of environment pollution. Composite beam is a new hybrid beam system which is not needed a fire proofing protection process. Composite beam has better construction capacity than that of RC system and has more economic advantages than that of wide flange steel beam. In this paper, structural design guide lines of composite beam were provided to apply design and construction.

• 항공우주시스템공학회지
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• 제5권1호
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• pp.17-23
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• 2011

Since the time, cost and lack of regulatory information and guidance, one of the largest regulatory obstacles for an airframe manufacturer of polymer based advanced composite materials in certified aircraft applications, is to generate design allowables that will satisfy Airworthiness Regulations. In the past two decades, the design allowables used in military aircraft had been generated and applied in Korea, however the qualification of composite materials used in certifying airframe structure was not accomplished for design and demonstration of compliance to applicable airworthiness regulation. It is the intend of this paper that provide the basis of composite material qualification for small aircraft certification to the airworthiness regulation.

• 동력기계공학회지
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• 제10권4호
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• pp.133-138
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• 2006

Effective thermal conductivity of particulate reinforced composite has been predicted by Eshelby's equivalent inclusion method modified with Mori-Tanaka's mean field theory. The predicted results are compared with the experimental results from the literature. The model composite is polymer matrix filled with ceramic particles such as silica, alumina, and aluminum nitride. The preliminary examination by Eshelby type model shows that the predicted results are in good agreements with the experimental results for the composite with perfect spherical filler. As the shape of filler deviates from the perfect sphere, the predicted error increases. By using the aspect ratio of the filler deduced from the fixed filler volume fraction of 30%, the predicted results coincide well with the experimental results for filler volume fraction of 40% or less. Beyond this fraction, the predicted error increases rapidly. It can be finally concluded from the study that Eshelby type model can be applied to predict the thermal conductivity of the particulate composite with filler volume fraction less than 40%.

• 항공우주시스템공학회지
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• 제13권4호
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• pp.10-17
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• 2019

This study is concerned with a numerical analysis based on the finite element method to describe the effect of midplane delamination in smart laminated composite plate structures. A new finite element model for centrally located delamination and healthy section was developed and coded in Matlab. The transient analysis of delaminated composite plate with integrated Active Fiber Composite (AFC) was investigated in the present article. The formulation of the governing equation was based on the minimum total potential energy approach. The Newmark time integration technique was employed to solve the differential equations. A parametric study on the effects of boundary conditions and AFC patch location, in presence of delamination on the laminated plate were studied.

• Geomechanics and Engineering
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• 제13권4호
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• pp.621-640
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• 2017

The double-row long-short composite anti-sliding piles system is an effective way to control the landslides with high thrust. In this study, The double-row long-short composite anti-sliding piles with different load segment length (cantilever length) and different pile row spacing were studied by a series of physical tests, by which the influences of load segment length of rear-row piles as well as pile row spacing on the mechanical response of double-row long-short composite anti-sliding pile system were investigated. Based on the earth pressures in front of and behind the piles obtained during tests, then the maximum bending moments of the fore-row and the rear-row piles were calculated. By ensuring a equal maximum moments in the fore-row and the rear-row piles, the optimum lengths of the rear-row piles of double-row long-short composite system under different piles spacing were proposed. To investigate the validity of the reduced scale tests, the full-scale numerical models of the landside were finally conducted. By the comparisons between the numerical and the physical test results, it could be seen that the reduced scale tests conducted in this study are reliable. The results showed that the double-row long-short composite anti-sliding piles system is effective in the distribution of the landslide thrust to the rear-row and the fore-row piles.

• 비파괴검사학회지
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• 제23권1호
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• pp.7-13
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• 2003

형상기억복합재료를 제조하기 위하여 핫프레스 방법을 이용하여 최적의 제조조건을 도출하였으며 냉간압연에 의해 기지재와 강화재의 계면접합을 강화하여 강도를 증가시켰다. 이러한 방법에 의해 제조된 형상기억복합재료에 대하여 외부 하중에 의한 손상정도와 균열의 발생을 감지하여 균열 발생 및 진전을 억제하는 온라인 모니터링 시스템을 개발하고자 한다. 이를 위하여 음향방출 신호의 파라미터를 이용하여 손상에 따른 최적의 AE 파라미터를 도출하였으며 가역시스템을 이용하여 형상기억합금을 가열함으로써 형상기억합금의 수축에 의한 복합재료 내부에 균열진전을 억제시키는 시스템을 개발하였다