• 제목/요약/키워드: Displacement matrix

검색결과 413건 처리시간 0.026초

정전기력을 이용한 미소기전 구동기의 고유치 변화 해석에 관한 연구 (Numerical Approach for Frequency-Shifting Analysis of Electrostatic Micro-Mechanial Actuator)

  • 이완술;권기찬;김봉규;조지현;윤성기
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2001년도 춘계학술대회논문집A
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    • pp.854-859
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    • 2001
  • An eigenvalue analysis of a tunable micro-mechanical actuator is presented. The actuator is modeled as a continuum structure. The eigenvalue modified by the tuning voltage is computed through the linearization of the relation between the electrostatic force and the displacement at the equilibrium. A staggered algorithm is employed to perform the coupled analysis of the electrostatic and elastic fields. The stiffness matrix of the actuator is modified at this equilibrium state. The displacement field is perturbed using an eigenmode profile of the actuator. The configuration change of the actuator due to perturbation modifies the electrostatic field and thus the electrostatic force. The equivalent stiffness matrix corresponding to the perturbation and the change in the electrostatic force is then added to stiffness matrix in order to explain natural frequency shifting. The numerical examples are presented and compared with the experiments in the literatures.

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Determination of collapse safety of shear wall-frame structures

  • Cengiz, Emel Yukselis;Saygun, Ahmet Isin
    • Structural Engineering and Mechanics
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    • 제27권2호
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    • pp.135-148
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    • 2007
  • A new finite shear wall element model and a method for calculation of 3D multi-storied only shear walled or shear walled - framed structures using finite shear wall elements assumed ideal elasto - plastic material are developed. The collapse load of the system subjected to factored constant gravity loads and proportionally increasing lateral loads is calculated with a method of load increments. The shape functions over the element are determined as a cubic variation along the story height and a linear variation in horizontal direction because of the rigid behavior of the floor slab. In case shear walls are chosen as only one element in every floor, correct solutions are obtained by using this developed element. Because of the rigid behavior of the floor slabs, the number of unknowns are reduced substantially. While in framed structures, classical plastic hinge hypothesis is used, in nodes of shear wall elements when vertical deformation parameter is exceeded ${\varepsilon}_e$, this node is accepted as a plastic node. While the system is calculated with matrix displacement method, for determination of collapse safety, plastic displacements and plastic deformations are taken as additional unknowns. Rows and columns are added to the system stiffness matrix for additional unknowns.

Research on Grid Side Power Factor of Unity Compensation Method for Matrix Converters

  • Xia, Yihui;Zhang, Xiaofeng;Ye, Zhihao;Qiao, Mingzhong
    • Journal of Power Electronics
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    • 제19권6호
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    • pp.1380-1392
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    • 2019
  • Input filters are very important to matrix converters (MCs). They are used to improve grid side current waveform quality and to reduce the input voltage distortion supplied to the grid side. Due to the effects of the input filter and the output power, the grid side power factor (PF) is not at unity when the input power factor angle is zero. In this paper, the displacement angle between the grid side phase current and the phase voltage affected by the input filter parameters and output power is analyzed. Based on this, a new grid side PF unity compensation method implemented in the indirect space vector pulse width modulation (ISVPWM) method is presented, which has a larger compensation angle than the traditional compensation method, showing a higher grid side PF at unity in a wide output power range. Simulation and experimental results verify that the analysis of the displacement angle between the grid side phase current and the phase voltage affected by the input filter and output power is right and that the proposed compensation method has a better grid side PF at unity.

Harmonic seismic waves response of 3D rigid surface foundation on layer soil

  • Messioud, Salah;Sbartai, Badredine;Dias, Daniel
    • Earthquakes and Structures
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    • 제16권1호
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    • pp.109-118
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    • 2019
  • This study, analyses the seismic response for a rigid massless square foundation resting on a viscoelastic soil layer limited by rigid bedrock. The foundation is subjected either to externally applied forces or to obliquely incident seismic body or surface harmonic seismic waves P, SV and SH. A 3-D frequency domain BEM formulation in conjunction with the thin layer method (TLM) is adapted here for the solution of elastodynamic problems and used for obtained the seismic response. The mathematical approach is based on the method of integral equations in the frequency domain using the formalism of Green's functions (Kausel and Peck 1982) for layered soil, the impedance functions are calculated by the compatibility condition. In this study, The key step is the characterization of the soil-foundation interaction with the input motion matrix. For each frequency the impedance matrix connects the applied forces to the resulting displacement, and the input motion matrix connects the displacement vector of the foundation to amplitudes of the free field motion. This approach has been applied to analyze the effect of soil-structure interaction on the seismic response of the foundation resting on a viscoelastic soil layer limited by rigid bedrock.

공기막 구조물의 형상해석 (Shape Finding Analysis of Pneumatic Structure)

  • 권택진;서삼열;이장복
    • 한국전산구조공학회:학술대회논문집
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    • 한국전산구조공학회 1994년도 봄 학술발표회 논문집
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    • pp.57-64
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    • 1994
  • The purpose of this paper is to find minimum surface shape of pneumatic structure using the finite element method. The pneumatic membrane structure is a kind of large deformation problem and very flexible composite material, which mean geomatric nonlinearity. It is not to resist for compression and resultant moment. As the displacement due to internal pressure is getting bigger, it should be considered the direction of forces. It becomes non-linear problem with the non-conservative force. The follower-force depends on the deformation and the direction of force is normal to each element. The solution process is obtained the new stiffness matrix (load correction matrix) depending on deformation through each iterated step. However, the stiffness matrix have not the symmetry and influence on the time of covergence. So in this paper Newton-Rhapson method for solving non-linear problem and for using symmetic matrix, the load direction is changed in each iterated step using the transformation matrix.

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불연속 금속복합체에서의 탄성거동에 관한 미세구조역학적 해석 (A Micromechanical Analysis on the Elastic Behavior in Discontinuous Metal Matrix Composites)

    • 한국생산제조학회지
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    • 제6권3호
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    • pp.58-64
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    • 1997
  • A micromechanics model to describe the elastic behavior of fiber or whisker reinforced metal matrix composites was developed and the stress concentrations between reinforcements were investigated using the modified shear lag model with the comparison of finite element analysis (FEA). The rationale is based on the replacement of the matrix between fiber ends with the fictitious fiber to maintain the compatibility of displacement and traction. It was found that the new model gives a good agreement with FEA results in the small fiber aspect ratio regime as well as that in the large fiber aspect ratio regime. By the calculation of the present model, stress concentration factor in the matrix and the composite elastic modulus were predicted accurately. Some important factors affecting stress concentrations, such as fiber volume fraction, fiber aspect ratio, end gap size, and modulus ratio, were also discussed.

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회전축요소의 전달행렬의 이용과 진동해석 (Using of Transfer Matrix for Shaft Element and Vibration Analysis)

  • 전오성
    • 한국소음진동공학회논문집
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    • 제12권2호
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    • pp.161-169
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    • 2002
  • Based on the analytic expression for the elasto-dynamic behavior of rotating shaft, the transfer matrix is formulated for the shaft element with uniform cross-section. Timoshenko beam theory is Introduced for modeling the behavior of shaft. Complex variables representing the displacement, slope, moment and shear force are used for deriving the transfer matrix between both ends of the shaft element. Simulation result obtained by applying the transfer matrix to a general rotor model is compared with the reference result and proved to be exact. Natural frequencies and the corresponding modes are analyzed with varying the bearing: stiffness. The generally used bearings are considered for discussions. and the bearing stiffness is shown to affect the vibration characteristics of rotor.

전달(傳達)매트릭스법(法)에 의(依)한 선체특설늑골(船體特設肋骨) 해석(解析) (The Stress Analysis of Web Frame by the Transfer Matrix Method)

  • 임상진;양영순
    • 대한조선학회지
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    • 제12권1호
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    • pp.31-36
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    • 1975
  • As the size of tanker increase, the analysis and strength prediction of the transverse web frames in a tanker have become important problems. Therefore, several papers dicussed the subject and various method of analysis have been presented. Most of these studies are based on the elastic framework analysis. Framework analysis is carried out by the matrix methods. The matrix methods used most frequently are the displacement method, force method and the transfer matrix method. In this paper, the analysis is carried out by the transfer matrix method. The program has been tested by IBM 1130 and the results of example show good agreements with those by the program of stress analysis, STRESS, which was developed in M.I.T.

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혼합유한요소모델을 이용한 두꺼운 복합적층판의 불규칙 진동해석(1)-이론적 고찰 (Random Vibration Analysis of Thick Composite Laminated Plate Using Mixed Finite Element Model (1))

  • 석근영;강주원
    • 한국공간정보시스템학회:학술대회논문집
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    • 한국공간정보시스템학회 2004년도 춘계 학술발표회 논문집 제1권1호(통권1호)
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    • pp.190-196
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    • 2004
  • Thick composite laminated plates is considered in 3D finite-element. To consider continuity of transverse stresses and displacement field, mixed finite-element has been developed by using layerwise theory and the minimum potential energy principle. Mixed finite-element has been enforced through the thick direction, Z, of a laminated plate by considering six degree-of-freedoms per node. Six degree-of-freedoms are three displacement components in the coordinate axes directions and three transverse stress components ${\sigma}_z,\;{\tau}_{xz},\;{\tau}_{yz}$. The model maintain the fundamental elasticity relations that are stress-strain relation and displacement-strain relation, because the transverse stress components invoked as nodal degrees of freedom by using the fundamental elasticity relationship between th components of stress and displacement. Random vibration analysis of the model is performed by computing consistent mass matrix and computing covariance in frequency domain technique.

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다층 층간분리된 적층 판의 유한요소 자유진동해석 (Finite Element Analysis for Free Vibration of Laminated Plates Containing Multi-Delamination)

  • Taehyo Park;Seokoh Ma
    • 한국전산구조공학회:학술대회논문집
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    • 한국전산구조공학회 2003년도 가을 학술발표회 논문집
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    • pp.37-44
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    • 2003
  • In this proposed work, computational, finite element model far multi-delaminated plates will be developed. In the current analysis procedures of multi-delaminated plates, different elements are used at delaminated and undelaminated region separately. In the undelaminated region, plate element based on Mindlin plate theory is used in order to obtain accurate results of out-of-plane displacement of thick plate. And for delaminated region, plate element based on Kirchhoff plate theory is considered. To satisfy the displacement continuity conditions, displacement vector based on Kirchhoff theory is transformed to displacement of transition element. Element mass and stiffness matrices of each region (delaminated, undelaminated and transition region) will be assembled for global matrix.

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