• 제목/요약/키워드: elastic properties

검색결과 2,361건 처리시간 0.032초

다방향으로 입체 보강된 복합재 노즐의 열탄성해석 (Thermo-Elastic Analysis of the Spatially Reinforced Composite Nozzle)

  • 유재석;김광수;이상의;김천곤
    • 한국복합재료학회:학술대회논문집
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    • 한국복합재료학회 2002년도 추계학술발표대회 논문집
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    • pp.100-105
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    • 2002
  • This paper predicts the material properties of spatially reinforced composites (SRC) and analyzes the thermo-elastic behavior of a kick motor nozzle manufactured from that material. To find the appropriate SRC structure for the nozzle throat that satisfies given design conditions, the equivalent material properties of the SRC are predicted using the superposition method for those of rod and matrix. Studied are the elastic behavior, temperature distribution, and thermo-elastic behavior of a kick motor nozzle composed of carbon/carbon SRC as a throat part. The elastic deformation of the nozzle composed of 3D carbon/carbon SRC shows asymmetry in a circumferential direction. However, 4D carbon/carbon SRC nozzle shows uniform deformation in the circumferential direction. Stress concentration in connecting parts of the kick motor nozzle is ultimately high due to the high temperature gradient in each connecting part. The thermo-elastic deformations of both the 3D and the 4D SRC nozzles are uniform in the circumferential direction due to the isotropy of CTE of each SRC. The deformation of the 3D SRC nozzle is a slightly smaller than that of the 4D SRC nozzle in the nozzle throat, which is favorably effective on rocket thrust. The circumferential stress is the most critical component of the kick motor nozzle. The 4D SRC nozzle having 1,1,1,1.7 diameters in each direction has the smallest circumferential stress among several SRC nozzles.

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초탄성고무 물성평가용 미소압입시험법 개발 및 검증 (Development and Verification of Micro-indentation Technique for Material Property Evaluation of Hyper-elastic Rubber)

  • 이형일;이진행
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2004년도 춘계학술대회
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    • pp.132-137
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    • 2004
  • In this work, effects of hyper-elastic rubber material properties on the indentation load-deflection curve and subindenter deformation are first examined via [mite element (FE) analyses. An optimal data acquisition spot is selected, which features maximum strain energy density and negligible frictional effect. We then contrive two normalized functions. which map an indentation load vs. deflection curve into a strain energy density vs. first invariant curve. From the strain energy density vs. first invariant curve, we can extract the rubber material properties. This new spherical indentation approach produces the rubber material properties in a manner more effective than the common uniaxial tensile/compression tests. The indentation approach successfully measures the rubber material properties and the corresponding nominal stress.strain curve with an average error less than 3%.

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탄성 댐퍼가 추가된 대형철골 구조물의 응답특성 (Response Of Steel Frame Structures With Added Elastic Dampers)

  • 배춘희;조철환;양경현;박영필
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2002년도 춘계학술대회논문집
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    • pp.808-812
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    • 2002
  • The feasibility of using elastic dampers to mitigate earthquake-induced structural response is studied in this paper. The properties of elastic dampers are briefly described. A procedure for evaulating the elastic damping effect when added to a structure is proposed in which the damping effect of elastic dampers is incorporated into modal damping ratios through an energy approach. Computer simulation of the damped response of a multi-storey steel frame structure shows significant reduction in floor displacement levels.

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Plastic behavior of circular discs with temperature-dependent properties containing an elastic inclusion

  • Zarandi, Somayeh Bagherinejad;Wang, Yun-Che;Novozhilova, Olga V.
    • Structural Engineering and Mechanics
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    • 제58권4호
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    • pp.731-743
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    • 2016
  • Plastic behaviors, based on the von Mises yield criterion, of circular discs containing a purely elastic, circular inclusion under uniform temperature loading are studied with the finite element analysis. Temperature-dependent mechanical properties are considered for the matrix material only. In addition to analyzing the plane stress and plane strain disc, a 3D thin disc and cylinder are also analyzed to compare the plane problems. We determined the elastic irreversible temperature and global plastic collapse temperature by the finite element calculations for the plane and 3D problem. In addition to the global plastic collapse, for the elastically hard case, the plane stress problem and 3D thin disc may exhibit a local plastic collapse, i.e. significant pile up along the thickness direction, near the inclusion-matrix interface. The pileup cannot be correctly modeled by the plane stress analysis. Furthermore, due to numerical difficulties originated from large deformation, only the lower bound of global plastic collapse temperature of the plane stress problem can be identified. Without considerations of temperature-dependent mechanical properties, the von Mises stress in the matrix would be largely overestimated.

신축성에 따른 여고생 교복의 착용감에 관한 연구(제1보) -역학적 특성과 보온성에 관하여- (A Study on Wearing Sensations of Girls'High School Uniforms Based on Elasticity(1) -Focusing on Mechanical Properties and Insulation-)

  • 민경혜;류덕환
    • 한국의류학회지
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    • 제27권5호
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    • pp.545-553
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    • 2003
  • A good school uniform leads students to good behavior and have them enjoy desirable school life. Therefore a better fabric for girls' high school uniform suggested through two series of studies; first, examined the various aspects of current uniforms. Second, made a new fabric for uniform considering elasticity for activity and comfortableness, and compared its characteristics with those of the current uniforms. The results are as follows; 1 Most of students wanted uniforms considering elasticity for activity and wearing. 2. The measurement of the elasticities of the uniform materials showed that the material which was made using the elastic material was more elastic than the currently used material by 42.12% in summer material and 20.05% in winter one. 3. The analysis using the combination of the values of mechanical properties showed that the elastic material was better in the wearing, tactile senses, and drape properties than the current material, even though it was a little worse in shape-stability. 4. To compare the thermal insulation, clo values were measured. For winter uniform, the elastic material was better than the current one in keeping warm. However, This study did not find any big difference between summer uniform materials.

복합재 라미네이트의 두께방향 열탄성 물성치 계산 (Analytical Determination of Out-of-Plane Thermo-elastic Properties for Laminated Composite Plate)

  • 김경표
    • 한국산학기술학회논문지
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    • 제16권4호
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    • pp.2407-2414
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    • 2015
  • 본 논문은 적층된 복합재 라미네이트의 두께방향(out-of-plane) 열탄성 물성치 계산식에 관하여 서술하였다. 다양한 적층패턴을 유도된 계산식에 적용한 결과, 섬유방향이 단방향 0도로 구성된 라미네이트에서 총 플라이수 중 10% 이상이 모두 90도 섬유방향으로 이루어져 있거나, 또는 15도 이상의 섬유방향으로 형성된 적층패턴을 가지는 라미네이트(Laminate)의 두께방향 물성치를 복합재 라미나(lamina)의 단섬유방향과 직교하는 물성치(transverse property)로 가정하는 것은 적절하지 않은 것으로 나타났다.

Theoretical Estimates for Elastic Properties of Biaxial Nematics

  • Allender, David W.
    • 한국정보디스플레이학회:학술대회논문집
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    • 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.I
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    • pp.195-198
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    • 2005
  • Using theoretical analysis based on Landau theory, it is shown that only five phenomenological parameters are necessary to describe the twelve bulk elastic constants of a biaxial nematic phase. Further, a simple method for determining the values of these five parameters experimentally is given. Comparison with the values of the well-known splay, twist, and bend elastic constants of the uniaial nematic is made.

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Al$_2$O$_3$-TiO$_2$세라믹의 플라즈마 용사과정에서 미세구조의 변화와 용사코팅층의 탄성에 대한 연구 (A Study on the elastic properties of coated layers and the changes of microstructure in plasma spray coating of $Al_2$O$_3$-TiO$_2$ ceramics)

  • 이형근;김대훈;황선효;안병국;김병희;서동수;안명구
    • Journal of Welding and Joining
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    • 제14권6호
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    • pp.109-118
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    • 1996
  • Al$_2$O$_3$-TiO$_2$powders of six different compositions were plasma-sprayed on Ti substrate. The spray powders and the spray coated layers were analysed and compared using SEM and X-RD. The elastic properties (specific elastic constant and damping coefficient) of the coated specimens were measured in order to select the optimum composition range of ceramics for use in a speaker diaphragm. A correlation between the microstructure and elastic properties was also investigated. When $Al_2$O$_3$powders with 0- 13% TiO$_2$were plasma sprayed, the coated layers were composed of metastable y-Al$_2$O$_3$with small amount of $\alpha$-Al$_2$O$_3$and the content of $\alpha$-Al$_2$O$_3$was increased with TiO$_2$content. Specific elastic constant was rapidly increased with 2 and 13% TiO$_2$addition to $Al_2$O$_3$. The internal damping was nearly unchanged with TiO$_2$content The specific elastic constant seemed to be dependent on the content of $\alpha$-Al$_2$O$_3$in the coated layer.

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The Mechanical Properties of Alkali Resistance Glass Fiber Reinforced Cement under Different Curing Conditions

  • Jeong, Moon-Young;Song, Jong-Taek
    • The Korean Journal of Ceramics
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    • 제4권3호
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    • pp.189-192
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    • 1998
  • The mechanical properties of alkali resistance (AR) glass fiber reinforced cement(GFRC) under different curing conditions were investigated in this study. The specimens were formed by extrusion process, and then steam cured and autoclaved. An autoclaved specimen showed the elastic-brittle behavior up to 4% of fiber volume fraction. However, it was found that the fracture behavior for cured specimen was changed to the elastic-plastic with crack branches fracture at greater than 3 vol.% of fiber.

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셀 크기와 셀벽 두께를 고려한 하니컴 재료의 탄성 해석 (Elastic Analysis of Honeycomb Materials Considering Cell Size and Cell Wall Thickness)

  • 김형구;최낙삼
    • 한국복합재료학회:학술대회논문집
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    • 한국복합재료학회 2003년도 춘계학술발표대회 논문집
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    • pp.157-160
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    • 2003
  • Honeycomb sandwich composite structures have been widely used in aircraft and military industry because of light weight and high stiffness. Accurate mechanical properties of honeycomb materials are needed for analysis of sandwich composites. In this study, theoretical formula for elastic modulus of honeycomb materials was established considering bending and axial deformations of their walls. Finite-element analysis results were compared with theoretical ones of the longitudinal and transverse moduli of honeycomb materials. Consequently, the mechanical properties of honeycomb materials could be analytically predicted.

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