• Geomechanics and Engineering
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• 제19권5호
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• pp.369-381
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• 2019

The objective of this paper is to study the two dimensional deformation in transversely isotropic thermoelastic medium without energy dissipation due to time harmonic sources using new modified couple stress theory, a continuum theory capable to predict the size effects at micro/nano scale. The couple stress constitutive relationships have been introduced for transversely isotropic thermoelastic medium, in which the curvature tensor is asymmetric and the couple stress moment tensor is symmetric. Fourier transform technique is applied to obtain the solutions of the governing equations. Assuming the deformation to be harmonically time-dependent, the transformed solution is obtained in the frequency domain. The application of a time harmonic concentrated and distributed sources have been considered to show the utility of the solution obtained. The displacement components, stress components, temperature change and couple stress are obtained in the transformed domain. A numerical inversion technique has been used to obtain the solutions in the physical domain. The effects of angular frequency are depicted graphically on the resulted quantities.

• Structural Engineering and Mechanics
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• 제76권1호
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• pp.17-26
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• 2020

The objective of this paper is to study the deformation in transversely isotropic thermoelastic solid using new modified couple stress theory subjected to ramp-type thermal source and without energy dissipation. This theory contains three material length scale parameters which can determine the size effects. The couple stress constitutive relationships are introduced for transversely isotropic thermoelastic solid, in which the curvature (rotation gradient) tensor is asymmetric and the couple stress moment tensor is symmetric. Laplace and Fourier transform technique is applied to obtain the solutions of the governing equations. The displacement components, stress components, temperature change and couple stress are obtained in the transformed domain. A numerical inversion technique has been used to obtain the solutions in the physical domain. The effects of length scale parameters are depicted graphically on the resulted quantities. Numerical results show that the proposed model can capture the scale effects of microstructures.

• 지질공학
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• 제17권4호
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• pp.673-680
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• 2007

2007년 1월 20일 발생한 오대산지진과 관련된 지진원 상수(지진원기구, 진원깊이, 규모, 지진원 특성 등)를 지진모멘트텐서 방법을 이용하여 분석하였다. 3개의 지각속도 모델에 의한 각각의 지각반응을 분석을 위한 그린함수로 이용하였다. 분석된 6개의 지진모멘트텐서 성분을 조합한 결과 오대산지진은 거의 북북동 방향의 주향을 가진 주향단층의 운동에 의해 발생된 것으로 해석된다. 진원깊이는 약 11 km의 값을 가지고 있으며 6개의 지진모멘트 성분을 분석한 결과 CLVD 성분이 약 7%의 값을 가지고 있어 순수 단층면위의 미끄러짐 현상에 의해 발생된 것으로 해석되었다. 지진원기구의 주향이 오대산 단층의 주향과 일치하고 있고, 또한 진앙도 오대산 단층의 지표 연장선과 밀접한 관계를 보여주고 있으므로 오대산 단층이 지진유발 단층인 것으로 해석된다.

• Computers and Concrete
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• 제19권6호
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• pp.701-710
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• 2017

In this study, the thermoelastic beam in modified couple stress theory due to laser source and heat flux is investigated. The beam are heated by a non-Guassian laser pulse and heat flux. The Euler Bernoulli beam theory and the Laplace transform technique are applied to solve the basic equations for coupled thermoelasticity. The simply-supported and isothermal boundary conditions are assumed for both ends of the beam. A general algorithm of the inverse Laplace transform is developed. The analytical results have been numerically analyzed with the help of MATLAB software. The numerically computed results for lateral deflection, thermal moment and axial stress due to laser source and heat flux have been presented graphically. Some comparisons have been shown in figures to estimate the effects of couple stress on the physical quantities. A particular case of interest is also derived. The study of laser-pulse find many applications in the field of biomedical, imaging processing, material processing and medicine with regard to diagnostics and therapy.

• Steel and Composite Structures
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• 제1권2호
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• pp.187-200
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• 2001

Most of the portal frames are designed these days by the application of plastic analysis, with the normal assumption being made that the column bases are pinned. However, the couple produced by the compression action of the inner column flange and the tension in the holding down bolts will inevitably generate some moment resistance and rotational stiffness. Full-scale portal frame tests conducted during a previous research program had suggested that this moment can be as much as 20% of the moment of resistance of the column. The size of this moment of resistance is particularly important for the design of the tensile capacity of the holding down bolts and also the bearing resistance of the foundation. The present research program is aiming at defining this moment of resistance in simple design terms so that it could be included in the design of the frame. The investigation also included the study of the semi-rigid behaviour of the column base/foundation, which, to a certain extent, affects the overall loading capacity and stiffness of the portal frames. A series of column bases with various details were tested and were used to calibrate a finite element model which is able to simulate the action of the holding down bolts, the effect of the concrete foundation and the deformation of the base plate.

• Interaction and multiscale mechanics
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• 제5권4호
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• pp.385-397
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• 2012

In this paper the dynamic stiffness matrix method was used for the free vibration analysis of axially moving micro beam with constant velocity. The extended Hamilton's principle was employed to derive the governing differential equation of the problem using the modified couple stress theory. The dynamic stiffness matrix of the moving micro beam was evaluated using appropriate expressions of the shear force and bending moment according to the Euler-Bernoulli beam theory. The effects of the beam size and axial velocity on the dynamic characteristic of the moving beam were investigated. The natural frequencies and critical velocity of the axially moving micro beam were also computed for two different end conditions.

• 대한치과교정학회지
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• 제50권5호
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• pp.356-359
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• 2020

Forces and moments delivered by a straight wire connecting two orthodontic brackets are statically indeterminate and cannot be estimated using the classical equations of static equilibrium. To identify the mechanics of such two-bracket systems, Burstone and Koenig used the principles of linear beam theory to estimate the resulting force systems. In the original publication, however, it remains unclear how the force systems were calculated because no reference or computational details on the underlying principles have been provided. Using the moment carry-over principle and the relative angulation of the brackets, a formula was derived to calculate the relative moments of the two brackets. Because of the moment equilibrium, the vertical forces that exist as a force-couple on the two brackets can also be calculated. The accuracy of the proposed approach can be validated using previously published empirical data.

• 한국강구조학회 논문집
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• 제24권5호
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• pp.521-534
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• 2012

본 연구에서는 합성보의 특징을 활용하고, 일부 고강도강 적용이 가능한 단면을 개발하여 이에 대한 기초연구를 실시하였다. 본 논문은 그 첫 번째로 단위부재인 합성보의 휨성능을 실험을 통해 평가하였다. 실험결과를 통해 기존 합성보의 공칭강도 산정식 적용여부를 검토하였고, 각 구성부재를 주요변수로 하여 실험하였다. 실험결과 신형상 U형 합성보의 내력평가는 콘크리트 압축강도와 강재의 인장강도에 의한 우력모멘트로 소요모멘트에 저항하는 것으로 평가하는 것이 적합하며, 보 춤 및 강판 두께에 비례하여 내력이 안정적으로 증가하였으며, 연성거동을 하는 것으로 나타났다.

• 지질공학
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• 제2권2호
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• pp.155-165
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• 1992

본 연구는 한반도의 지진지체구조 특성에 부합되는 내진설계용 부지응답 스펙트럼 작성을 위한 유사지진 선정에 관한 연구이다. Seismic Moment Tensor를 이용 파형을 Inversion한 결과에 의하면 지진원 특성상, Kern Conty 지진(1952년 7월 21일, 리히터 규모 ML = 7.2)은 한반도 지진지체구조 특성에 부합되는 현실적으로 유사한 외국의 지진들 중의 하나로서, 선정된 Kern Conty 지진으로 부터 발생한 강지진동 자료를 전산처리하여 표준응답 스펙트럼과 일반적 특성을 비교하여 보는 일도 의미있는 일이라고 할 수 있다.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2001년도 종합학술발표회 논문집 Vol.11 No.1
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• pp.111-114
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• 2001

In this paper, the electromagnetic coupling problems are tackled on slots with nonzero thickness. The analysis is carried out by combination of the thin-wire concept and the Method of Moment(MoM) for the sake of improving computation efficiency. Under the conditions to be presented, slots can be replaced with wires that have effective radii. Also, the infinite summation-type Green's functions are calculated for the parallel-pale structure. A slot in an infinite ground is analyzed and its results are compared with the measurement in a literature. Furthermore, it is examined how the slots couple in parallel plates.