• Title, Summary, Keyword: composite materials

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Establishment of Aerospace Composite Materials Data Center for Qualification

  • Lee, Ho-Sung;Rhee, Seung Yun;Yoon, Jong-Hoon;Yoo, Joon-Tae;Min, Kyung Ju
    • Composites Research
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    • v.28 no.6
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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.

Feasibility Study of the Damage Monitoring for Composite Materials by the Piezoelectric Method (압전기법을 이용한 복합재료 손상모니터링의 가능성에 관한 연구)

  • Hwang, Hui-Yun
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.32 no.11
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    • pp.918-923
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    • 2008
  • Since crack detection for laminated composites in-service is effective to improve the structural reliability of laminated composites, it have been tried to detect cracks of laminated composites by various nondestructive methods. An electric potential method is one of the widely used approaches for detection of cracks for carbon fiber composites, since the electric potential method adopts the electric conductive carbon fibers as reinforcements and sensors and the adoption of carbon fibers as sensors does not bring strength reduction induced by embedding sensors into the structures such as optical fibers. However, the application of the electric method is limited only to electrically conductive composite materials. Recently, a piezoelectric method using piezoelectric characteristics of epoxy adhesives has been successfully developed for the adhesive joints because it can monitor continuously the damage of adhesively bonded structures without producing any defects. Polymeric materials for the matrix of composite materials have piezoelectric characteristics similarly to adhesive materials, and the fracture of composite materials should lead to the fracture of polymeric matrix. Therefore, it seems to be valid that the piezoelectric method can be applied to monitoring the damage of composite materials. In this research, therefore, the feasibility study of the damage monitoring for composite materials by piezoelectric method was conducted. Using carbon fiber epoxy composite and glass fiber composite, charge output signals were measured and analyzed during the static and fatigue tests, and the effect of fiber materials on the damage monitoring of composite materials by the piezoelectric method was investigated.

Synthesis and characterization of polybenzoxazole/graphene oxide composites via in situ polymerization

  • Lim, Jun;Kim, Min-Cheol;Goh, Munju;Yeo, Hyeounk;Shin, Dong Geun;Ku, Bon-Cheol;You, Nam-Ho
    • Carbon letters
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    • v.14 no.4
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    • pp.251-254
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    • 2013
  • In this study, poly(amic acid) was prepared via a polycondensation reaction of 3,3'-dihydroxybenzidine and pyromellitic dianhydride in an N-methyl-2-pyrrolidone solution; reduced graphene oxide/polybenzoxazole (r-GO/PBO) composite films, which significantly increased the electrical conductivity, were successfully fabricated. GO was prepared from graphite using Brodie's method. The GO was used as nanofillers for the preparation of r-GO/PBO composites through an in situ polymerization. The addition of 50 wt% GO led to a significant increase in the electrical conductivity of the composite films by more than sixteen orders of magnitude compared with that of pure PBO films as a result of the electrical percolation networks in the r-GO during the thermal treatment at various temperatures within the films.

Application of Composite Materials in Korean Express Tilting Train(TTX) System (한국형 틸팅차량 시스템에서의 복합재료 적용)

  • 박기진;신광복;한성호
    • Proceedings of the Korean Society For Composite Materials Conference
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    • pp.65-68
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    • 2003
  • Using composite materials for lilting train system has many advantages such as manufacturing variety, specific high-strength & stiffness characteristics, and long-life durability, but the strongest advantage could be the possibility of lightweight product. In the leading countries, the composite materials are used for the material fer drivers' cabs, interior/exterior equipments for railway train, and it is now developing the composite materials applied for the train car body structure. In this paper, we examine the use of composite materials for the drivers' cabs and interior/exterior equipments for the developing tilting train in Korea, and review the car body design using composite materials.

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Laboratory experiments on the improvement of rockfill materials with composite grout

  • Wang, Tao;Liu, Sihong;Lu, Yang
    • Geomechanics and Engineering
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    • v.17 no.3
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    • pp.307-316
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    • 2019
  • Dam deformation should be strictly controlled for the construction of 300 m-high rockfill dams, so the rockfill materials need to have low porosity. A method of using composite grout is proposed to reduce the porosity of rockfill materials for the construction of high rockfill dams. The composite grout is a mixture of fly ash, cement and sand with the properties of easy flow and post-hardening. During the process of rolling compaction, the grout admixture sprinkled on the rockfill surface will gradually infiltrate into the inter-granular voids of rockfill by the exciting force of vibratory roller to reduce the porosity of rockfill. A visible flowing test was firstly designed to explore the flow characteristics of composite grout in porous media. Then, the compressibility, shear strength, permeability and suffusion susceptibility properties of composite grout-modified rockfill are studied by a series of laboratory tests. Experimental results show that the flow characteristics of composite grout are closely related to the fly ash content, the water-to-binder ratio, the maximum sand size and the content of composite grout. The filling of composite grout can effectively reduce the porosity of rockfill materials, as well as increase the compression modulus of rockfill materials, especially for loose and gap-graded rockfill materials. Composite grout-modified rockfill tends to have greater shear strength, larger suffusion erosion resistance, and smaller permeability coefficient. The composite grout mainly plays the roles of filling, lubrication and cementation in rockfill materials.

Characteristic Studies of Plasma Treated unidirectional Hildegardia Populifolia Fabric

  • Prasad, C. Venkata;Lee, D.W.;Sudhakara, P.;Jagadeesh, D.;Kim, B.S.;Bae, S.I.;Song, J.I.
    • Composites Research
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    • v.26 no.1
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    • pp.54-59
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    • 2013
  • This study deals with effect of plasma treatment on the properties of unidirectional ligno cellulosic fabric Hildegardia Populofolia (HDP) fabric. Thermal stability of the fabric was determined by differential scanning calorimetry (DSC) and Thermo gravimetric analysis (DSC). Morphological properties was analyzed by SEM analysis and found that the surface was rough upon plasma treatment which provides good interfacial adhesion with matrix during composite fabrication. Thermal stability and mechanical properties of the plasma treated fabric slightly increases compare to alkali and untreated fabric. It was observed that tensile properties of the fabric increases upon plasma treatment due to the formation of rough surface. SEM analysis indicates formation of rough surface on plasma treatment which helps in increasing the interfacial interaction between the matrix (hydrophobic) and fabric (hydrophilic).

A Study on the Vibration Characteristics of Laminated Composite Materials Rectangular Plates (적층 복합재료 사각판의 진동특성에 관한 연구)

  • 허동현;신귀수;정인성
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.486-490
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    • 1997
  • Composite materials have varios complicated characteristics to the ply materials, ply orientations, ply stacking sequences and boundary conditions. Therefore, it is difficult to analysis composite materials. For efficient use of composite materials in engineering applications the dynamic behavior, that is, natural frequencies, nodal patterns should be informed. This study presents the experimental and FEM results for the free vibration of symmetrically and antisymmetrically laminated composite and hybrid composite rectangular plates. In order to demonstrate the validity of the experiment, FEM analysis using ANSYS was performed and natural frequencies experimentally obtined is compared with that calculated by FEM analysis. The results obtained from both experiment and FEM analysis show a good agreement.

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Selection Methodology of Tool for Co-cured Composite Materials (동시경화용 복합재료의 특성에 따른 금형의 선택방법)

  • 홍중표;이종옥;이원곤;홍정수;지우석;조한준
    • Proceedings of the Korean Society For Composite Materials Conference
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    • pp.183-188
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    • 2002
  • Co-cured composite materials has its own characteristics, so its thermal expansion is different each other. The selection of tool material for co-cured composite part in high temperature more over $350^{circ}F$ and 50 Psi pressure have to consider part thermal expansion, size, shape, and economic aspect in production line. So it is important choose tooling material in manufacturing composite parts. We called the tool for airplane composite parts as BAJ (Bonding Assembly Jig). Composite parts are cured on the BAJ in autoclave. BAJ have to stable at high temperature over $350^{circ}F$ and 50 Psi pressure, Considering composite parts' dimensional tolerance compare to heat up in autoclave. This paper come from the results of the experiment at the composite parts production line and review other aircraft company's method for tooling This is for the engineer engaged in composite parts manufacturing.

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A Study on Precise Drilling Characteristics of Carbon Fiber Epoxy Composite Materials (탄소섬유 에폭시 복합재료의 정밀드릴가공 특성에 관한 연구)

  • 김홍배
    • Journal of the Korean Society for Precision Engineering
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    • v.15 no.10
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    • pp.203-208
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    • 1998
  • Carbon fiber epoxy composite materials are widely used in the structures of aircrafts, robots and other machines because of their high specific strength, high specific stiffness and high damping. In order for the composite materials to be used in the aircraft structures or machine elements, accurate surfaces for bearing mounting or joints must be provided, which require precise machining. In this paper, the machinability characterisitcs of the drilling operation of the carbon fiber epoxy composite materials was experimentally investigated. The experimental results are as follows 1.The entrance of hole is very good manufacturing existing, but exit come to occur sever surface exfoliation. 2. The cutting force in drilling of the carbon fiber epoxy composite materials is decreased as the drilling speed increased. 3.The hole of the carbon fiber epoxy composite materials is not good manufacturing by use of the standard twist, therefore, the new drill designed in order to accurate hole.

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