• Title/Summary/Keyword: Static analysis

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Crash Optimization of an Automobile Frontal Structure Using Equivalent Static Loads (등가정하중을 이용한 차량 전면구조물 충돌최적설계)

  • Lee, Youngmyung;Ahn, Jin-Seok;Park, Gyung-Jin
    • Transactions of the Korean Society of Automotive Engineers
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    • v.23 no.6
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    • pp.583-590
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    • 2015
  • Automobile crash optimization is nonlinear dynamic response structural optimization that uses highly nonlinear crash analysis in the time domain. The equivalent static loads (ESLs) method has been proposed to solve such problems. The ESLs are the static load sets generating the same displacement field as that of nonlinear dynamic analysis. Linear static response structural optimization is employed with the ESLs as multiple loading conditions. Nonlinear dynamic analysis and linear static structural optimization are repeated until the convergence criteria are satisfied. Nonlinear dynamic crash analysis for frontal analysis may not have boundary conditions, but boundary conditions are required in linear static response optimization. This study proposes a method to use the inertia relief method to overcome the mismatch. An optimization problem is formulated for the design of an automobile frontal structure and solved by the proposed method.

Local Nonlinear Static Analysis via Static Condensation (강성응축기법을 이용한 국부 비선형 정적 해석)

  • Shin, Han-Seop;Oh, Min-Han;Boo, Seung-Hwan
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.27 no.1
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    • pp.193-200
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    • 2021
  • In this study, an analysis technique using static condensation is proposed for an efficient local nonlinear static analysis. The static condensation method is a model reduction method based on the degrees of freedom, and the analysis model is divided into a target part and a condensed part to be omitted. In this study, the nonlinear and linear parts were designated to the target and the omitted parts, respectively, and both the stiffness matrix and load vector corresponding to the linear part were condensed into the nonlinear part. After model condensation, the reduced model comprising the stiffness matrix and the load vector for the nonlinear part is constructed, and only this reduced model was updated through the Newton-Raphson iteration for an efficient nonlinear analysis. Finally, the efficiency and reliability of the proposed analysis technique were presented by applying it to various numerical examples.

Static Stability Analysis for Gait Control of a Quardruped Walking Robot (사각보행로보트의 걸음새 제어를 위한 정적 안정도 해석)

  • 임준홍;서일홍;임미섭
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.38 no.12
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    • pp.1014-1021
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    • 1989
  • The problem of controlling static gaits for a quadruped walking robot is investigated. A theoretical approach to gait study is proposed in which the static stability margins for periodic gaits are expressed in terms of the kinematic gait formula. The effects fo the stride length on static stability are analyzed and the relations between static stability and initial body configurations are examined. It is shown that the moving velocity can be increased to some extent without affecting stability margins for a given initial body configuration. Computer simulations are performed to verify the analysis.

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Static Stiffness Tuning Method of Rotational Joint of Machining Center (머시닝센터 회전 결합부의 정강성 Tuning 기법)

  • Kim, Yang-Jin;Lee, Chan-Hong
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.19 no.6
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    • pp.797-803
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    • 2010
  • A method has been developed to tune the static stiffness at a rotation joint considering the whole machine tool system by interactive use of finite element method and experiment. This paper describes the procedure of this method and shows the results. The method uses the static experiment on measurement model which is set-up so that the effects of uncertain factors can be excluded. For FEM simulation, the rotation joint model is simplified using only spindle, bearing and spring. At the rotation joint, the damping coefficient is ignored, The spindle and bearing is connected by only spring. By static experiment, 500 N is forced to the front and behind portion of spindle and the deformation is measured by capacitive sensor. The deformation by FEM simulation is extracted with changing the static stiffness from the initial static stiffness considering only rotation joint. The tuning static stiffness is obtained by exploring the static stiffness directly trusting the deformation from the static experiment. Finally, the general tuning method of the static stiffness of machine tool joint is proposed using the force stream and the modal analysis of machine tool.

Development of Nonlinear Static Design Sensitivity Analysis Based ANSYS (ANSYS 비선형 정적설계민감도해석 외부모듈 개발)

  • Choi, Byung-Nam;Jung, Jae-Jun;Yoo, Jung-Hoon;Lee, Tae-Hee
    • Proceedings of the KSME Conference
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    • 2001.06c
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    • pp.543-547
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    • 2001
  • CAE has been settled down to an indispensable tool for the simulation of a mechanical system according to the development of computer-aided analysis rapidly. Particularly finite element programs have advanced to the one of most valuable things in the filed of CAE due to the remarkable progress in the implementation. But since this analysis tool mostly provides the result of the analysis, it cannot satisfy designers who are seeking for information to improve their designs. Therefore, design sensitivity analysis or optimization module has been incorporated into commercial FEA programs to satisfy the desire of designers since 1990s. Design sensitivity analysis is to compute the rate of change of response with respected to design variable. Design sensitivity analysis is classfied into static design sensitivity analysis, Eigenvalue design sensitivity analysis and dynamic design sensitivity analysis. In this research, it will be presented to nonlinear static design sensitivity analysis formulation and nonlinear static design sensitivity analysis external module based ANSYS have been developed and illustrated an example to verify the developed module.

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A hybrid 8-node hexahedral element for static and free vibration analysis

  • Darilmaz, Kutlu
    • Structural Engineering and Mechanics
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    • v.21 no.5
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    • pp.571-590
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    • 2005
  • An 8 node assumed stress hexahedral element with rotational degrees of freedom is proposed for static and free vibration analyses. The element formulation is based directly on an 8-node element. This direct formulation requires fewer computations than a similar element that is derived from an internal 20-node element in which the midside degrees of freedom are eliminated by expressing them in terms of displacements and rotations at corner nodes. The formulation is based on Hellinger-Reissner variational principle. Numerical examples are presented to show the validity and efficiency of the present element for static and free vibration analysis.

Nonlinear Dynamic Response Structural Optimization of an Automobile Frontal Structure Using Equivalent Static Loads (등가정하중법을 이용한 차량 전면 구조물의 비선형 동적 반응 구조최적설계)

  • Yoon, Shic;Jeong, Seong-Beom;Park, Gyung-Jin
    • Proceedings of the KSME Conference
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    • 2008.11a
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    • pp.1156-1161
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    • 2008
  • Nonlinear dynamic analysis is generally used in automobile crash analysis and structural optimization considering crashworthiness uses the results of nonlinear dynamic analysis. Automobile crash optimization has high nonlinearity and difficulty in calculating sensitivity. Recently the equivalent static load (ESL) method has been proposed in order to overcome these difficulties. The ESL is the static load set generating the same displacement field as the nonlinear dynamic displacement field at each time step in dynamic analysis. From various researches regarding the ESL method, it has been proved that the ESL method is fairly useful. The ESL method can mathematically optimize a crash optimization problem through nonlinear analysis and well developed static optimization. The ESL is applied to nonlinear dynamic structural optimization of the automobile frontal impact problem. An automobile bumper is optimized. The mass of the structure is minimized while some constraints are satisfied.

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Static equilibrium and linear vibration analysis of a high speed electric train system (고속 전철 시스템의 정적 평형 및 선형 진동 해석)

  • 김종인;유홍희;황요하
    • Proceedings of the KSR Conference
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    • 1998.11a
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    • pp.305-312
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    • 1998
  • A formulation to perform static equilibrium and linear vibration analysis is presented in this paper. The formulation employs minimum number of equations of motion which are derived by using a partial velocity matrix, The static equilibrium analysis is performed first, then the linear vibration analysis is performed at the static equilibrium position. By using the formulation presented in this paper, static equilibrium and linear vibration analysis of a high speed electric train system are performed. A single bogie system, a power vehicle, and a train system which consists of five vehicles are analyzed, respectively. Natural frequencies and a few lowest mode shapes of the three are identified in this paper.

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Development of a Static and Dynamic Analysis System for Motor-Integrated High-Speed Spindle Systems Using Timoshenko Theory and Finite Element Method (Timoshenko 이론과 유한요소법을 이용한 모터내장형 고속주축계의 정특성/동특성 해석시스템 개발)

  • 이용희;김석일;김태형;이재윤
    • Journal of the Korean Society for Precision Engineering
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    • v.15 no.8
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    • pp.11-16
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    • 1998
  • Recently, the motor-integrated spindle systems have been used to simplify the machine tool structure, to improve the motion flexibility of machine tool, and to perform the high-speed machining. In this study, a static and dynamic analysis system for motor-integrated high-speed spindle systems is developed based on Timoshenko theory, finite element method and windows programming techniques. Since the system has various analysis modules related to static deformation analysis, modal analysis, frequency response analysis, unbalance response analysis and so on, it is useful in performing systematically the design and evaluation processes of motor-integrated high-speed spindle systems under windows GUI environment.

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