• Title/Summary/Keyword: finite element-transfer matrix method

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Forced Vibration Analysis of Lattice Type Structure by Transfer Stiffness Coefficient Method (전달강성계수법에 의한 격자형 구조물의 강제진동 해석)

  • 문덕홍;최명수
    • Journal of KSNVE
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    • v.8 no.5
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    • pp.949-956
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    • 1998
  • Complex and large lattice type structures are frequently used in design of bridge, tower, crane and aerospace structures. In general, in order to analyze these structures we have used the finite element method(FEM). This method is the most widely used and powerful method for structural analysis lately. However, it is necessary to use a large amount of computer memory and computational time because the FEM requires many degrees of freedom for solving dynamic problems exactly for these complex and large structures. For analyzing these structures on a personal computer, the authors developed the transfer stiffness coefficient method(TSCM). This method is based on the concept of the transfer of the nodal dynamic stiffness coefficient matrix which is related to force and displacement vector at each node. And we suggested TSCM for free vibration analysis of complex and large lattice type structures in the previous report. In this paper, we formulate forced vibration analysis algorithm for complex and large lattice type structures using extened TSCM. And we confirmed the validity of TSCM through computational results by the FEM and TSCM, and experimental results for lattice type structures with harmonic excitation.

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On triply coupled vibration of eccentrically loaded thin-walled beam using dynamic stiffness matrix method

  • Ghandi, Elham;Shiri, Babak
    • Structural Engineering and Mechanics
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    • v.62 no.6
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    • pp.759-769
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    • 2017
  • The effect of central axial load on natural frequencies of various thin-walled beams, are investigated by some researchers using different methods such as finite element, transfer matrix and dynamic stiffness matrix methods. However, there are situations that the load will be off centre. This type of loading is called eccentric load. The effect of the eccentricity of axial load on the natural frequencies of asymmetric thin-walled beams is a subject that has not been investigated so far. In this paper, the mentioned effect is studied using exact dynamic stiffness matrix method. Flexure and torsion of the aforesaid thin-walled beam is based on the Bernoulli-Euler and Vlasov theories, respectively. Therefore, the intended thin-walled beam has flexural rigidity, saint-venant torsional rigidity and warping rigidity. In this paper, the Hamilton‟s principle is used for deriving governing partial differential equations of motion and force boundary conditions. Throughout the process, the uniform distribution of mass in the member is accounted for exactly and thus necessitates the solution of a transcendental eigenvalue problem. This is accomplished using the Wittrick-Williams algorithm. Finally, in order to verify the accuracy of the presented theory, the numerical solutions are given and compared with the results that are available in the literature and finite element solutions using ABAQUS software.

Dynamic Behavior Analysis for HDD Spindle Motors with Rotor Eccentricity (HDD 스핀들 구동용 BLDC 전동기의 편심을 고려한 동적 거동 해석)

  • 김태종;김경태;황상문
    • Journal of KSNVE
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    • v.10 no.6
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    • pp.977-984
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    • 2000
  • Vibration of disk drive spindle is one of the major limiting factors in achieving higher track densities in hard disk drives. Vibration of a BLDC motor is a coupled phenomenon between mechanical characteristics and magnetic origins through the motor air-gap. In this paper, radial magnetic forces for symmetric and asymmetric BLDC motor are calculated with respect to the various rotor eccentricity using analytic method. Based on the results of the radial magnetic forces, transient whirl responses of the spindle motor are analyzed using finite element and transfer matrices. Results show that an asymmetric motor has a worse effects on unbalanced magnetic forces and vibration when mechanical and magnetic coupling exists.

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Finite Element Analysis on the Impactive Deformation of a Cu Particle in Cold Spraying Processing : Effect of Velocity (저온분사 공정에서 구리분말 충돌속도 변화에 따른 충돌변형 거동의 유한요소해석)

  • Cho, Kyu-Jin;Yoon, Seung-Chae;Kim, Hyoung-Seop
    • Journal of Powder Materials
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    • v.15 no.3
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    • pp.227-233
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    • 2008
  • Dynamic plastic deformation behavior of copper particles occurred during the cold spray processing was numerically analyzed using the finite element method. The study was to investigate the impact as well as the heat transfer phenomena, happened due to collision of the copper particle of $20{\mu}m$ in diameter with various initial velocities of $300{\sim}600m/s$ into the copper matrix. Effective strain, temperature and their distribution were investigated for adiabatic strain and the accompanying adiabatic shear localization at the particle/substrate interface.

Effects of initial imperfections on nonlinear behaviors of thin-walled members

  • Ohga, M.;Takaue, A.;Shigematsu, T.;Hara, T.
    • Structural Engineering and Mechanics
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    • v.11 no.5
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    • pp.519-534
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    • 2001
  • The effect of the initial imperfections on the nonlinear behaviors and ultimate strength of the thin-walled members subjected to the axial loads, obtained by the finite element stability analysis, are examined. As the initial imperfections, the bucking mode shapes of the members are adopted. The buckling mode shapes of the thin-walled members are obtained by the transfer matrix method. In the finite element stability analysis, isoparametric degenerated shell element is used, and the geometrical and material nonlinearity are considered based on the Green Lagrange strain definition and the Prandtl-Reuss stress-strain relation following the von Mises yield criterion. The U-, box- and I-section members subjected to the axial loads are adopted for numerical examples, and the effects of the initial imperfections on the nonlinear behaviors and ultimate strength of the members are examined.

Time Historical Response Analysis of Tree Structure by Transfer Stiffness Coefficient Method (전달강성계수법에 의한 분기형 구조물의 시긴이력응답해석)

  • 문덕홍;강현석;최명수
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 1998.04a
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    • pp.426-431
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    • 1998
  • This, paper describes formulation for time historical response analysis of vibration for tree structure. This method is derived from a combination of the transfer stiffness coefficient method and the Newmark-.betha. method. And This present method improves the computational accuracy of the transient vibration response analysis remarkably owing to several advantages of the transfer stiffness coefficient method. We regarded the structure as a lumped mass system here. The analysis algorithm for the time historical response was formulated for the tree structure. The validity of the present method compared with the transfer matrix method and the FEM(Finite Element Method) for transient vibration analysis is demonstrated through the numerical computations.

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Free Vibration Analysis of Lattice Type Structures by the Combination and Transfer of Stiffness Coefficient (강성계수의 조합 및 전달에 의한 격자형 구조물의 자유진동 해석)

  • 문덕홍;최명수;강화중;강현석
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 1997.04a
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    • pp.169-175
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    • 1997
  • Recently it is increased by degrees to produce complex and large lattice structures such as bridge, tower, crane, and space structures. In general, in order to analyse these structures we have used finite element method(FEM). In this method, however, it is necessary to use a large amount of computer memory and to take long computation time. For overcoming this problem, the Authors have developed the transfer dynamic stiffness coefficient method(TDSCM) which consists on the concept of the substructure synthesis method and transfer influence coefficient method. In this paper, the new free vibration analysis method for large type lattice structure is formulated by the TDSCM. And the results obtained by TDSCM are compared with those obtained by FEM, transfer matrix method and experiment. And it is confirmed for TDSCM to be the numerical high accuracy and high speed structure analysis method.

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An investigation on the vibrations of laminated shells under aeroacoustic loads using a WFE approach

  • Errico, Fabrizio;Franco, F.;Ichchou, M.;De Rosa, S.;Petrone, G.
    • Advances in aircraft and spacecraft science
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    • v.6 no.6
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    • pp.463-478
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    • 2019
  • The present work investigates the effect on the flow-induced vibrations of the lay-up sequence of composite laminated axisymmetric structures, using an hybrid approach based on a wave finite element and a transfer matrix method. The structural vibrations, under deterministic distributed pressure loads, diffuse acoustic field and turbulent boundary layer excitations, are analysed and compared. A multi-scale approach is used for the dynamic analysis of finite structures, using an elementary periodic subsystem. Different flow regimes and shell curvatures are analysed and the computational efficiency is also discussed.

Analytical Technique and Load Transfer Features on Pile Using Finite Difference Method (유한차분법을 이용한 말뚝의 하중전이특성 및 해석기법)

  • Han, Jung-Geun;Lee, Jae-Ho
    • Journal of the Korean Society of Environmental Restoration Technology
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    • v.9 no.5
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    • pp.10-21
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    • 2006
  • For analyze of the bearing capacity, skin friction and settlements of pile on axial compressive loading, both Load transfer tests of pile and pile loading test in field have application to commonly before pile installing. A bearing capacity of pile was affected by the characteristics of surrounding ground of pile. Especially, that is very different because of evaluation of settlement due to each soil conditions of ground depths. The ground characteristics using evaluation of bearing capacity of pile through load transfer analysis depends on N values of SPT, and then a bearing capacity of pile installed soft ground and refilled area may be difficult to rational evaluation. An evaluation of bearing capacity on pile applied axial compressive loading was effected by strength of ground installed pile, unconfined compressive strength at pile tip, pile diameter, rough of excavated surface, confining pressure and deformation modules of rock etc and these are commonly including the unreliability due to slime occurred excavation works. Load transfer characteristics considered ground conditions take charge of load transfer of large diameter pile was investigated through case study applied load transfer tests. To these, matrix analytical technique of load transfer using finite differential equation developed and compared with the results of pile load test.

Calculation of Transverse Vibration of Ship`s Propulsion Shaftings by the Finite Element Method (有限要素法에 의한 推進軸系의 광振動計算에 관한 硏究)

  • Jeon, Hio-Jung;Kim, Hi-Cheol
    • Journal of Advanced Marine Engineering and Technology
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    • v.3 no.1
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    • pp.2-18
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    • 1979
  • Due to increasing ship dimensions and installed propulsive power, resonance frequencies of the propeller shaft system tend to decrease and they can appear in some cases within the operating range of the shaft revolution. For calculation of transverse shaft vibrations, various methods have been proposed but as they are mainly for approximate calculation, no contented results are obtained. For fairly accurate estimation of resonance frequencies in the design stage, one can use transfer matrix method of the finite element method and former is rather prefered in ordinary cases. In this study, the finite element method which is utilized for calculation of the propulsion shaft alignment, is introduced to derive the vibration equation of the ship's propulsion shaftings. The digital computer program is developed to solve the above equation, and the details of preparing the input data are described. The method presented in the underlying report was applied to the shafting of ship which has a lignumvitae bearing to verify its reliability and the results of calculation and those of the measurements on rotating shaft show a good agreement. Calculating methods of exciting of forces and damping forces are also discussed for future work.

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