• Title, Summary, Keyword: Isotropic loading

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Fatigue Damage of Quasi-Isotropic Composite Laminates Under Tensile Loading in Different Directions

  • Kim, In-Kweon;Kong, Chang-Duk;Han, Kyung-Seop
    • Journal of Mechanical Science and Technology
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    • v.14 no.5
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    • pp.483-489
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    • 2000
  • The purpose of this work is to investigate fatigue damage of quasi-isotropic laminates under tensile loading in different directions. Low cycle fatigue tests of $[0/-60/60]_s$ laminates and $[30/-30/90]_s$ laminates were carried out. Material systems used are AS4/Epoxy and AS4/PEEK. The fatigue damage of $[30/-30/90]_s$ is very different from that of $[0/-60/60]_s$. The experimental results are compared with the result obtained from the method for determining strain energy release rate components proposed by the authors. The analytical results were in good agreement with the experimental results. It is proved that the failure criterion based on the strain energy release rate is an appropriate approach to predict the initiation and growth of delaminations under cyclic loading.

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Fatigue Damage of Quasi-Isotropic Composite Laminates Under Tensile Loading in Different Directions (인장하중방향 변화를 받는 의사등방성 복합재 적층판의 피로손상)

  • 김택현
    • Journal of The Korean Society of Manufacturing Technology Engineers
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    • v.8 no.2
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    • pp.80-85
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    • 1999
  • The purpose of this work is to investigate fatigue damage of quasi-isotropic laminates under tensile loading in different directions. Low cycle fatigue tests of [0/-60/+60]a laminates and [+30/-30/90]s lamina tes were carried out. Material systems used are AS4/Epoxy and AS4/PEEK. The fatigue damage of [+30/-30/90]s is very different from that of [0/-60/+60]s. The position of delamination generated at AS4/Epoxy and AS$/PEEK laminates were differentiated by the matrix difference that is, we suppose, the value of both GIcr(critical energy release rate of mode-I) and GIIIcr(critical energy release rate of mode-III) difference.

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Stress state around cylindrical cavities in transversally isotropic rock mass

  • Lukic, Dragan C.;Prokic, Aleksandar D.;Brcic, Stanko V.
    • Geomechanics and Engineering
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    • v.6 no.3
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    • pp.213-233
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    • 2014
  • The present paper is dealing with the investigation of the stress field around the infinitely long cylindrical cavity, of a circular cross section, contained in the transversally isotropic elastic continuum. Investigation is based upon the determination of the stress function that satisfies the biharmonic equation, for the given boundary conditions and for rotationaly symmetric loading. The solution of the partial differential equation of the problem is given in the form of infinite series of Bessel's functions. Determination of the stress-strain field around cavities is a common requirement for estimation of safety of underground rock excavations.

Elastic Analysis of a Half-Plane Containing Multiple Inclusions Using Volume Integral Equation Method (체적 적분방정식법을 이용한, 다수의 함유체를 포함한 반무한 고체에서의 탄성해석)

  • Lee, Jung-Ki;Ku, Duck-Young
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.32 no.2
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    • pp.148-161
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    • 2008
  • A volume integral equation method (VIEM) is used to calculate the plane elastostatic field in an isotropic elastic half-plane containing multiple isotropic or anisotropic inclusions subject to remote loading. A detailed analysis of stress field at the interface between the matrix and the central inclusion in the first column of square packing is carried out for different values of the distance between the center of the central inclusion in the first column of square packing of inclusions and the traction-free surface boundary in an isotropic elastic half-plane containing multiple isotropic or anisotropic inclusions. The method is shown to be very accurate and effective for investigating the local stresses in an isotropic elastic half-plane containing multiple isotropic or anisotropic inclusions.

Analysis of the Behavior of Undrained Pore Water Pressure in Saturated Sand by Isotropic Loading Test (포화된 사질토에서 등방재하시험에 의한 비배수 공극수압의 거동분석)

  • Eam, Sung-Hoon
    • Journal of The Korean Society of Agricultural Engineers
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    • v.47 no.4
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    • pp.43-52
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    • 2005
  • It is known in some literatures that the B value is not equal to unity in saturated soil when effective stress is given, in which the B Value is the ratio of measured excess pore water pressure and isometric loading pressure. In this study the B value was measured on various effective stresses and on various incremental loading stresses in various grain size of specimens with saturated sand. The test results showed that the B value was affected largely by grain size of sand in specimen and the amount of effective stress. There was the semi-logarithmic relationship between B value and effective stress, and also there was the linear relationship between the gradient of the former semi-logarithmic relationship and grain size of specimen.

Dynamic Mode III Crack Propagated with Constant Velocity at Interface Between Isotropic and Orthotropic Material (등방성체와 직교이방성체의 접합계면네 내재된 동적모드 III 균열의 등속전파)

  • Lee, Gwang-Ho;Hwang, Jae-Seok;Yu, Jae-Yong
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.20 no.12
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    • pp.3828-3837
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    • 1996
  • The dynamic problems of interface crack propagated with constant velocity along the interface of bimateraial composed of isotropic and orthotropicmaterial under antiplane loading condition are studied in this paper. The general dynamic stress fields and displacement fields of mode III are derived when interface crack between isotropic and orthotropic material is propagating with constant velocity. The general dynamic stress fields and displacement fields in isotropic material. Finally, the characteristics of interface crack propagation are studied with various properties of isotropic and orthotropic material and crack propagarion velocities.

Aluminum and E-glass epoxy plates behavior subjected to shock loading

  • Muhit, Imrose B.;Sakib, Mostofa N.;Ahmed, Sheikh S.
    • Advances in materials Research
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    • v.6 no.2
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    • pp.155-168
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    • 2017
  • The terrorist attacks and dangers by bomb blast have turned into an emerging issue throughout the world and the protection of the people and structures against terrorist acts depends on the prediction of the response of structures under blast and shock load. In this paper, behavior of aluminum and unidirectionally reinforced E-Glass Epoxy composite plates with and without focal circular holes subjected to shock loading has been identified. For isotropic and orthotropic plates (with and without holes) the classical normal mode approach has been utilized as a part of the processing of theoretical results. To obtain the accurate results, convergence of the results was considered and a number of modes were selected for plate with and without hole individually. Using a shock tube as a loading device, tests have been conducted to composite plates to verify the theoretical results. Moreover, peak dynamic strains, investigated by experiments are also compared with the theoretical values and deviation of the results are discussed accordingly. The strain-time histories are likewise indicated for a specific gauge area for aluminum and composite plates. Comparison of dynamic-amplification factors between the isotropic and the orthotropic plates with and without hole has been discussed.

Elastic Analysis of a Half-Plane Containing an Inclusion and a Void Using Mixed Volume and Boundary Integral Equation Method (혼합 체적-경계 적분방정식법을 이용한, 함유체와 공동을 포함한 반무한 고체에서의 탄성해석)

  • Lee, Jung-Ki;Yoon, Koo-Young
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.32 no.12
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    • pp.1072-1087
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    • 2008
  • A mixed volume and boundary integral equation method (Mixed VIEM-BIEM) is used to calculate the plane elastostatic field in an isotropic elastic half-plane containing an isotropic or anisotropic inclusion and a void subject to remote loading parallel to the traction-free boundary. A detailed analysis of stress field at the interface between the isotropic matrix and the isotropic or orthotropic inclusion is carried out for different values of the distance between the center of the inclusion and the traction-free surface boundary in an isotropic elastic half-plane containing three different geometries of an isotropic or orthotropic inclusion and a void. The method is shown to be very accurate and effective for investigating the local stresses in an isotropic elastic half-plane containing multiple isotropic or anisotropic inclusions and multiple voids.

Effects of Anisotropic Fiber Packing on Stresses in Composites (이방성 섬유의 배열이 복합재료의 응력에 미치는 영향)

  • Lee, Jung-Ki;Lee, Hyeong-Min
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.28 no.9
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    • pp.1284-1296
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    • 2004
  • In order to investigate effects of anisotropic fiber packing on stresses in composites, a Volume Integral Equation Method is applied to calculate the elastostatic field in an unbounded isotropic elastic medium containing multiple orthotropic inclusions subject to remote loading, and a Mixed Volume and Boundary Integral Equation Method is introduced for the solution of elastostatic problems in unbounded isotropic materials containing multiple anisotropic inclusions as well as one void under uniform remote loading. A detailed analysis of stress fields at the interface between the isotropic matrix and the central orthotropic inclusion is carried out for square, hexagonal and random packing of orthotropic cylindrical inclusions, respectively. Also, an analysis of stress fields at the interface between the isotropic matrix and the central orthotropic inclusion is carried out, when it is assumed that a void is replaced with one inclusion adjacent to the central inclusion of square, hexagonal and random packing of orthotropic cylindrical inclusions, respectively, due to manufacturing and/or service induced defects. The effects of random orthotropic fiber packing on stresses at the interface between the isotropic matrix and the central orthotropic inclusion are compared with the influences of square and hexagonal orthotropic fiber packing on stresses. Through the analysis of plane elastostatic problems in unbounded isotropic matrix with multiple orthotropic inclusions and one void, it will be established that these new methods are very accurate and effective for investigating effects of general anisotropic fiber packing on stresses in composites.

Experimental investigation on loading collapse curve of unsaturated soils under wetting and drying processes

  • Uchaipichat, Anuchit
    • Geomechanics and Engineering
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    • v.2 no.3
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    • pp.203-211
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    • 2010
  • An experimental program of isotropic loading tests on a compacted kaolin using a conventional triaxial equipment modified for testing unsaturated soils was perform to investigate a loading collapse curve of unsaturated soils along wetting and drying paths. The test data are presented in terms of effective stress on a range of constant suction. The suction hardening behavior was observed for both wetted and dried samples. With the use of an appropriate effective stress parameter, the unique relationship for loading collapse curve for wetting and drying processes was obtained.