• Title, Summary, Keyword: Isotropic Material

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Characteristics for a Mode III Crack Propagating along Interface between Isotropic and Functionally Gradient Material with Linear Property Gradation along X Direction (등방성과 X방향 선형함수구배 재료의 접합계면을 따라 전파하는 모드 III 균열의 특성)

  • Lee Kwang Ho
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.28 no.10
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    • pp.1500-1508
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    • 2004
  • Stress and displacement fields for a crack propagating along interface between isotropic material and functionally gradient one with linear property gradation along X direction are developed. The stress and displacement fields are obtained from the complex function of steady plane motion for isotropic and functionally gradient material (FGM). The stresses and displacement in isotropic material of bimaterial are not influenced by nonhomogeneity, however, the fields in FCM are influenced by nonhomogeneity in the terms of higher order, n$\geq$3. When the nonhomogeneous parameter in FGM is zero, or in area close to crack tip, the fields are identical to those of isotropic-isotropic bimaterial. Using these stress components, the effects of nonhomogeneity on stresses are discussed.

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.

Evaluation of thermal stability of quasi-isotropic composite/polymeric cylindrical structures under extreme climatic conditions

  • Gadalla, Mohamed;El Kadi, Hany
    • Structural Engineering and Mechanics
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    • v.32 no.3
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    • pp.429-445
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    • 2009
  • Thermal stability of quasi-isotropic composite and polymeric structures is considered one of the most important criteria in predicting life span of building structures. The outdoor applications of these structures have raised some legitimate concerns about their durability including moisture resistance and thermal stability. Exposure of such quasi-isotropic composite/polymeric structures to various and severe climatic conditions such as heat flux and frigid climate would change the material behavior and thermal viability and may lead to the degradation of material properties and building durability. This paper presents an analytical model for the generalized problem. This model accommodates the non-linearity and the non-homogeneity of the internal heat generated within the structure and the changes, modification to the material constants, and the structural size. The paper also investigates the effect of the incorporation of the temperature and/or material constant sensitive internal heat generation with four encountered climatic conditions on thermal stability of infinite cylindrical quasi-isotropic composite/polymeric structures. This can eventually result in the failure of such structures. Detailed critical analyses for four case studies which consider the population of the internal heat generation, cylindrical size, material constants, and four different climatic conditions are carried out. For each case of the proposed boundary conditions, the critical thermal stability parameter is determined. The results of this paper indicate that the thermal stability parameter is critically dependent on the cylinder size, material constants/selection, the convective heat transfer coefficient, subjected heat flux and other constants accrued from the structure environment.

A Study on the Development of Photoelastic Experiment Model Material for Transversely Isotropic Material (횡등방성체용 광탄성재료 개발에 관한 연구)

  • 황재석;김병일;이광호;최선호
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.19 no.8
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    • pp.1876-1888
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    • 1995
  • In this paper, glass surface-mat reinforced epoxy(G.S.R.E.) is developed, It is assured that the material(G.S.R.E.) can be used as photoelastic model material and it satisfy with the required properties of photoelastic model material. Therefore, the material can be used as model material of transparent photoelastic experiment when we analyze the stress distributions of transversely isotropic material by photoelastic experiment. When we use G.S.R.E. as photoelastic experiment model material, we had better use the G.S.R.E. which fiber volume ratio is less than 0.7% in the high temperature(stress freezing method) and than 1.74% in the room temperature. Relationships between stress fringe value and elastic modulus in transversely isotropic material are developed in this paper, it is assured by experiment that they are established in the room temperature or in the high temperature. Therefore we can obtain stress fringe value or elastic modulus from the relationships between stress fringe value and elastic modulus.

Computer modeling of elastoplastic stress state of fibrous composites with hole

  • Polatov, Askhad M.;Ikramov, Akhmat M.;Khaldjigitov, Abduvali A.
    • Coupled systems mechanics
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    • v.8 no.4
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    • pp.299-313
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    • 2019
  • The paper represents computer modeling of the deformed state of physically nonlinear transversally isotropic bodies with hole. In order to describe the anisotropy of the mechanical properties of transversally-isotropic materials a structurally phenomenological model has been used. This model allows representing the initial material in the form of the coupled isotropic materials: the basic material (binder) considered from the positions of continuum mechanics and the fiber material oriented along the anisotropy direction of the original material. It is assumed that the fibers perceive only the axial tensile-compression forces and are deformed together with the base material. To solve the problems of the theory of plasticity, simplified theories of small elastoplastic deformation have been used for a transversely-isotropic body, developed by B.E. Pobedrya. A simplified theory allows applying the theory of small elastoplastic deformations to solve specific applied problems, since in this case the fibrous medium is replaced by an equivalent transversely isotropic medium with effective mechanical parameters. The essence of simplification is that with simple stretching of composite in direction of the transversal isotropy axis and in direction perpendicular to it, plastic deformations do not arise. As a result, the intensity of stresses and deformations both along the principal axis of the transversal isotropy and along the perpendicular plane of isotropy is determined separately. The representation of the fibrous composite in the form of a homogeneous anisotropic material with effective mechanical parameters allows for a sufficiently accurate calculation of stresses and strains. The calculation is carried out under different loading conditions, keeping in mind that both sizes characterizing the fibrous material fiber thickness and the gap between the fibers-are several orders smaller than the radius of the hole. Based on the simplified theory and the finite element method, a computer model of nonlinear deformation of fibrous composites is constructed. For carrying out computational experiments, a specialized software package was developed. The effect of hole configuration on the distribution of deformation and stress fields in the vicinity of concentrators was investigated.

A Study on Stress Singularities for V-notched Cracks in Pseudo-isotropic and Anisotropic Dissimilar Materials (유사등방성과 이방성 이종재료 내의 V-노치 균열에 대한 응력특이성에 관한 연구)

  • Cho, Sang-Bong;Kim, Jin-Kwang
    • Journal of the Korean Society for Precision Engineering
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    • v.16 no.10
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    • pp.152-163
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    • 1999
  • The problem of eigenvalue and eigenvector for v-notched cracks in pseudo-isotropic and anisotropic dissimilar materials was obtained to discuss stress singularities from traction free boundary and perfect bonded interface conditions assuming like the form of complex stress function for v-notched cracks in an isotropic material. Eigenvalues were solved by a commercial numerical program, MATHEMATICA. The relation between wedged angle and material property for eigenvalue, ${\lambda}$ indicating stress singularities of v-notched cracks in pseudo-isotropic and anisotropic dissimilar materials was examined.

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Rayleigh waves in anisotropic magnetothermoelastic medium

  • Kumar, Rajneesh;Sharma, Nidhi;Lata, Parveen;Abo-Dahab, S.M.
    • Coupled systems mechanics
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    • v.6 no.3
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    • pp.317-333
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    • 2017
  • The present paper is concerned with the investigation of Rayleigh waves in a homogeneous transversely isotropic magnetothermoelastic medium with two temperature, in the presence of Hall current and rotation. The formulation is applied to the thermoelasticity theories developed by Green-Naghdi theories of Type-II and Type-III. Secular equations are derived mathematically at the stress free and thermally insulated boundaries. The values of Determinant of secular equations, phase velocity and Attenuation coefficient with respect to wave number are computed numerically. Cobalt material has been chosen for transversely isotropic medium and magnesium material is chosen for isotropic solid. The effects of rotation, magnetic field and phase velocity on the resulting quantities and on particular case of isotropic solid are depicted graphically. Some special cases are also deduced from the present investigation.

Crack Tip Creep Deformation Behavior in Transversely Isotropic Materials (횡방향으로 등방성인 재료에서 균열선단 크리프 변형 거동)

  • Ma, Young-Wha;Yoon, Kee-Bong
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.33 no.12
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    • pp.1455-1463
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    • 2009
  • Theoretical mechanics analysis and finite element simulation were performed to investigate creep deformation behavior at the crack tip of transversely isotropic materials under small scale creep (SCC) conditions. Mechanical behavior of material was assumed as an elastic-$2^{nd}$ creep, which elastic modulus ( E ), Poisson's ratio ( ${\nu}$ ) and creep stress exponent ( n ) were isotropic and creep coefficient was only transversely isotropic. Based on the mechanics analysis for material behavior, a constitutive equation for transversely isotropic creep behavior was formulated and an equivalent creep coefficient was proposed under plain strain conditions. Creep deformation behavior at the crack tip was investigated through the finite element analysis. The results of the finite element analysis showed that creep deformation in transversely isotropic materials is dominant at the rear of the crack-tip. This result was more obvious when a load was applied to principal axis of anisotropy. Based on the results of the mechanics analysis and the finite element simulation, a corrected estimation scheme of the creep zone size was proposed in order to evaluate the creep deformation behavior at the crack tip of transversely isotropic creeping materials.

Equivalent reinforcement isotropic model for fracture investigation of orthotropic materials

  • Fakoor, Mahdi;Rafiee, Roham;Zare, Shahab
    • Steel and Composite Structures
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    • v.30 no.1
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    • pp.1-12
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    • 2019
  • In this research, an efficient mixed mode I/II fracture criterion is developed for fracture investigation of orthotropic materials wherein crack is placed along the fibers. This criterion is developed based on extension of well-known Maximum Tensile Stress (MTS) criterion in conjunction with a novel material model titled as Equivalent Reinforced Isotropic Model (ERIM). In this model, orthotropic material is replaced with an isotropic matrix reinforced with fibers. A comparison between available experimental observations and theoretical estimation implies on capability of developed criterion for predicting both crack propagation direction and fracture instance, wherein the achieved fracture limit curves are also compatible with fracture mechanism of orthotic materials. It is also shown that unlike isotropic materials, fracture toughness of orthotic materials in mode $I(K)_{IC}{\mid})$ cannot be introduced as the maximum load bearing capacity and thus new fracture mechanics property, named here as maximum orthotropic fracture toughness in mode $I(K_{IC}{\mid}^{ortho}_{max})$ is defined. Optimum angle between crack and fiber direction for maximum load bearing in orthotropic materials is also defined.

Development of Resonant-Type Magnetometer Using High Permeability Isotropic Magnetic Material (고투자율 등방성 자기 물질을 이용한 공진형 마그네토미터 개발)

  • Yim, Jeong-Bin;Shim, Yeong-Ho;Ahn, Yeong-Sub
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.11 no.1
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    • pp.29-37
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    • 2005
  • The design and development if Resonant-type Magnetometer(RM) using isotropic magnetic with high permeability is described in this paper. At first, the relationship between the inductance L if the coil winding on a magnetic material and the permeability u(H) appearing in the magnetic material with isotropic and high permeability is defined as a background theory. Then the circuit if RM, which is to obtain the values if L as the change qf frequency is implemented using simple Schmitt Trigger Circuit Through the swinging tests, which is to evaluate the measurement ability if RM, the measurement possibility for the component of earth field was confined.

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