• Title/Summary/Keyword: anisotropic strength

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Bending Characteristic of CFRP & Hybrid Shaped Hat Structure Member According to Stacking Orientation Angle (적층각도변화에 따른 CFRP & 혼성 모자형 구조부재의 굽힘 특성)

  • Kim, Ji-Hoon;Kim, Jung-Ho;Cha, Cheon-Seok;Yang, In-Young
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.17 no.3
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    • pp.34-39
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    • 2008
  • In this study, CFRP(Carbon Fiber Reinforced Plastics) that has high specific strength and elastic modulus and low thermal strain was used as a material for the lightweight structural member. CFRP is a fiber material as anisotropic material. The anisotropic material is characterized by the change of its mechanical properties according to stacking orientation angle. CFRP orientation angle was oriented in [A/B]s in order to examine the effect of CFRP orientation angle on the characteristics of energy absorption. CFRP is very weak to the impact from the outside. So, when impact is applied to CFRP, its strength is rapidly lowered. The hybrid material was manufactured by combining CFRP to aluminum which is lightweight and widely used for structural members of the automobile. The hybrid member was shaped as a side member that could support the automobile engine and mount and absorb a large amount of impact energy at the front-end in case of automobile collision. The bending test device was manufactured in accordance with ASTM standard, and mounted to UTM for bending test. For comparing bending characteristics of the hybrid member with those of Aluminum and CFRP member, tests were performed for aluminum, CFRP and hybrid member, respectively.

Probabilistic bearing capacity of strip footing on reinforced anisotropic soil slope

  • Halder, Koushik;Chakraborty, Debarghya
    • Geomechanics and Engineering
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    • v.23 no.1
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    • pp.15-30
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    • 2020
  • The probabilistic bearing capacity of a strip footing placed on the edge of a purely cohesive reinforced soil slope is computed by combining lower bound finite element limit analysis technique with random field method and Monte Carlo simulation technique. To simulate actual field condition, anisotropic random field model of undrained soil shear strength is generated by using the Cholesky-Decomposition method. With the inclusion of a single layer of reinforcement, dimensionless bearing capacity factor, N always increases in both deterministic and probabilistic analysis. As the coefficient of variation of the undrained soil shear strength increases, the mean N value in both unreinforced and reinforced slopes reduces for particular values of correlation length in horizontal and vertical directions. For smaller correlation lengths, the mean N value of unreinforced and reinforced slopes is always lower than the deterministic solutions. However, with the increment in the correlation lengths, this difference reduces and at a higher correlation length, both the deterministic and probabilistic mean values become almost equal. Providing reinforcement under footing subjected to eccentric load is found to be an efficient solution. However, both the deterministic and probabilistic bearing capacity for unreinforced and reinforced slopes reduces with the consideration of loading eccentricity.

Strength characteristics of transversely isotropic rock materials

  • Yang, Xue-Qiang;Zhang, Li-Juan;Ji, Xiao-Ming
    • Geomechanics and Engineering
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    • v.5 no.1
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    • pp.71-86
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    • 2013
  • For rock materials, a transversely isotropic failure criterion established through the extended Lade-Duncan failure criterion incorporating an anisotropic state scalar parameter, which is a joint invariant of deviatoric microstructure fabric tensor and normalized deviatoric stress tensor, is verified with the results of triaxial compressive data on Tournemire shale. For torsional shear mode with $0{\leq}b{\leq}0.75$, rock shear strengths decrease with ${\alpha}$ increasing until the rock shear strength approaches minimum value at ${\alpha}{\approx}40^{\circ}$, and after this point, the rock shear strengths increase as ${\alpha}$ increases further. For the torsional shear mode with b > 0.75, rock shear strengths are almost constant for ${\alpha}{\leq}40^{\circ}$, but it increases with increase in ${\alpha}$ afterwards. The rock shear strength variation against ${\alpha}$ agrees with shear strength changing tendency of heavily OCR natural London Clays tested before. Prediction results show that the transversely isotropic failure criterion proposed in the paper is reasonable.

Strength Analysis for the Plate System of the Mark III Cargo Containment (Mark III 방열 판 구조물의 파손 강도 평가에 관한 연구)

  • Jeong, Han-Koo;Yang, Young-Soon
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.27 no.6
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    • pp.625-633
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    • 2014
  • Mark III CCS plate is considered in this paper to perform its strength assessment. Mark III CCS plate is designed and constructed by stacking various non-metallic engineering materials such as plywood, triplex and reinforced PU foam that are supported by series of mastic upon inner steel hull structure. From the viewpoint of structural analysis, this plated structure is treated as a laminated anisotropic structure. Commercially available general purpose finite element analysis programs such as MSC PATRAN and MARC are used to develop the finite element (FE) model of the Mark III CCS plate. Because of the characteristics of LNG cargo that the Mark III CCS plate deals with, it is subjected to a wide range of temperature variations, i.e. about $-163^{\circ}C$ to $20^{\circ}C$. Different material properties of the Mark III CCS plate at these temperature levels are considered in the FE model. Using the developed FE model, strength assessment procedure is developed incorporating various anisotropic failure criteria such as Hashin, Hill, Hoffman, Maximum stress and Tsai-Wu. The strength assessment is performed within the initial failure state of the Mark III CCS plate and, as a result, failure details such as failure locations and loads are identified.

Estimation of Discontinuity Orientations in Excavation Faces (굴착면에서의 분리면방향성 평가)

  • Ro, Byung-Don;Han, Byeong-Hyeon
    • Proceedings of the Korean Geotechical Society Conference
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    • 2005.03a
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    • pp.1484-1489
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    • 2005
  • An inhomogeneous and anisotropic rock has different properties at different location. Thus, this refers to any of the properties which we may be measuring. There are two concepts of rock mass, namely, CHILE(Continuous, Homogeneous, Isotropic, Linear Elastic) material and DIANE(Discontinuous, Inhomogeneous, Anisotropic, Non-linear Elastic) rock. The former is essentially the properties of intact rock, the latter is essentially the properties governed by the structure of rock. In geotechnical aspect, the most important parameter is strength of rock or rock mass. In particular, characteristics of strength of rock mass depend upon the orientation of discontinuities And this orientation of discontinuities has different properties at different direction of excavation. Therefore, it needs for characterization of different properties of discontinuity orientation against different direction of excavation.

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Elasto-plastic solution for cavity expansion problem in anisotropic and drained soil mass

  • Li, Chao;Zou, Jin-feng;Li, Liang
    • Geomechanics and Engineering
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    • v.19 no.6
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    • pp.513-522
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    • 2019
  • This study presents an elasto-plastic (EP) solution for drained cavity expansion on the basis of unified strength failure criterion and considers the influence of initial stress state. Because of the influence of initial consolidation of soil mass, the initial stress may be anisotropic in the natural soil mass. In addition, the undrained hypothesis is usually used in the calculation of cavity expansion problem, but most of the cases are in the drained situation in practical engineering. Eventually, the published solution and the presented solution are compared to verify the suitability of the study.

Effects of Anisotropic Consolidation on Flow Failure Behavior of a Silty Sand (이방압밀이 실트질 모래의 유동파괴거동에 미치는 영향)

  • 강병희;김방식;정혁일
    • Journal of the Korean Geotechnical Society
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    • v.17 no.5
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    • pp.173-180
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    • 2001
  • 이방압밀이 실트질모래의 정적재하에 의한 유동파괴거동에 미치는 영향을 연구하기 위하여 비배수삼축압축시험을 수행하였다. 이를 위하여 상대밀도가 약 17%인 공시체를 습윤다짐방법에 의해서 성형하고 4가지의 압밀응력비, 1.0, 0.7, 0.55, $K_{o}$ 로서 압밀시켰다. 시험결과로서 정상상태선은 p-q 공간상에서 압밀응력비에 관계없이 유일한 직선이며 collapse line의 기울기는 압밀응력비가 증가함에 따라 선형적으로 감소한다는 사실을 보여준다. 또한, 유동파괴거동을 보이는 느슨하게 다져진 실트질모래의 잔류강도($S_{us}$ )와 첨두강도($S^{p}$ )와의 관계는 압밀응력비의 크기에 관계없이 $S_{p}$ /$p_{c}$ = $A_{L}$ +$B_{L}$ ($S_{us}$ /$p_{c}$ )로 표현되는 일반식으로 나타낼 수 있으며 계수 $A_{L}$$B_{L}$은 압밀응력비의 크기에 따라 선형적으로 변하는 경향을 나타낸다.

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A Study on the Liquefaction Resistance of Anisotropic Sample under Real Earthquake Loading (이방 구속 조건에서 실지진 하중을 이용한 액상화 저항강도 특성 분석)

  • Lee, Chae-Jin;Jeong, Sang-Seom;Kim, Soo-Il
    • Proceedings of the Korean Geotechical Society Conference
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    • 2009.09a
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    • pp.1188-1191
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    • 2009
  • In this study, cyclic triaxial tests were performed with the samples which were anisotropically consolidated using irregular earthquake loading to consider in-situ condition and seismic wave. The consolidation pressure ratio(K) was changed from 0.5 to 1.0. The Ofunato and Hachinohe wave are applied as irregular earthquake loading and liquefaction resistance strength was estimated from excess pore water pressure(EPWP) ratio. As results of the cyclic triaxial tests, buildup of EPWP ratio increased as K value increased. It shows, that the isotropically consolidated sands is more susceptible to liquefaction than anisotropically consolidated sands under equal conditions such as confining pressure and dynamic loading.

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A Study on Bending Vibration of Laminated Rotating Disc (복합재료 회전체의 휨진동에 관한 연구)

  • Park, Sung-Jin;LEE, Seung-Hyeon
    • Journal of Urban Science
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    • v.10 no.1
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    • pp.11-20
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    • 2021
  • In this study, the vibration characteristics were theoretically analyzed by modeling a free isotropic rotating disk with an outer periphery with a fixed inner periphery, paying attention to disks used as storage devices for information devices, especially magnetic disks, magneto-optical disks, and compact disks in which the head and disk are non-contact. Iluminate with Composite materials represented by fiber-reinforced plastics (FRP) have high specific strength (strength/density) and specific stiffness (narrowness/density). It is used in the elements, and its use is rapidly expanding. Under this circumstance, the disk currently manufactured using an isotropic material made of various plastic materials such as aluminum or polycarbonate as a base material is an extremely anisotropic material made of a composite material, and the circumferential stiffness of the disk is made of reinforcing fibers in the circumferential direction. It is modeled as an anisotropic rotating disk with increased, and its influence on the vibration characteristics is revealed.

Anisotropic Dispersion Force Effects for Surface Liquid Crystal Alignment on Rubbed Polystyrene Surfaces (러빙처리된 폴리스타이렌막 표면에있어서의 표면 액정 배향에관한 이방성 분산력의 효과)

  • 서대식
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1996.05a
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    • pp.105-108
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    • 1996
  • We have studied the anisotropic dispersion force effects for surfaces alignment of liquid crystals (LCs) on rubbed polystyrene (PS) surfaces by unidirection. In microphotographs of the textures, we obtained the nematic (N) LCs are shown to align in both direction parallel and Perpendicular to the rubbing for region up to medium rubbing, however to align in the direction perpendicular to the rubbing for strong rubbing legion. We suggest that the anisotropic dispersion force is very important rather than macro-surface groove effect to uniform alignment of LCs. We also measured the temperature dependence of extrapolation length of 5CB on rubbed PS surfaces for strong rubbing. It is shown that the polar anchoring strength of 5CB is very weak on rubbed PS surface compared to the rubbed polyimide (Pl) surface.

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