• Title, Summary, Keyword: structural dynamic

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Structural Optimization of the Lower Parts in a Humanoid Considering Dynamic Characteristics (동적 특성을 고려한 휴머노이드 하체 부품의 구조최적설계)

  • Hong, Eul-Pyo;Lee, Il-Kwon;You, Bum-Jae;Kim, Chang-Hwan;Park, Gyung-Jin
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.32 no.10
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    • pp.882-889
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    • 2008
  • A humanoid is a robot with its overall appearance based on that of the human body. When the humanoid moves or walks, dynamic forces act on the body structure. Although the humanoid keeps the balance by using a precise control, the dynamic forces generate unexpected deformation or vibration and cause difficulties on the control. Generally, the structure of the humanoid is designed by the designer's experience and intuition. Then the structure can be excessively heavy or fragile. A humanoid design scenario for a systematic design is proposed to reduce the weight of the structure while sufficient strength is kept. Lower parts of the humanoid are selected to apply the proposed design scenario. Multi-body dynamics is employed to calculate the external dynamic forces on the parts and structural optimization is carried out to design the lower parts. Because structural optimization using dynamic forces directly is fairly difficult, linear dynamic response structural optimization using equivalent static loads is utilized. Topology and shape optimizations are adopted for two steps of initial and detailed designs, respectively. Various commercial software systems are used for analysis and optimization. Improved designs are obtained and the design results are discussed.

Effect of structure configurations and wind characteristics on the design of solar concentrator support structure under dynamic wind action

  • Kaabia, Bassem;Langlois, Sebastien;Maheux, Sebastien
    • Wind and Structures
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    • v.27 no.1
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    • pp.41-57
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    • 2018
  • Concentrated Solar Photovoltaic (CPV) is a promising alternative to conventional solar structures. These solar tracking structures need to be optimized to be competitive against other types of energy production. In particular, the selection of the structural parameters needs to be optimized with regards to the dynamic wind response. This study aims to evaluate the effect of the main structural parameters, as selected in the preliminary design phase, on the wind response and then on the weight of the steel support structure. A parametric study has been performed where parameters influencing dynamic wind response are varied. The study is performed using a semi-deterministic time-domain wind analysis method. Unsteady aerodynamic model is applied for the shape of the CPV structure collector at different configurations in conjunction with a consistent mass-spring-damper model with the corresponding degrees of freedom to describe the dynamic response of the system. It is shown that, unlike the static response analysis, the variation of the peak wind response with many structural parameters is highly nonlinear because of the dynamic wind action. A steel structural optimization process reveals that close attention to structural and site wind parameters could lead to optimal design of CPV steel support structure.

Structural Dynamic Optimization Using a Genetic Algorithm(GA) (유전자 알고리즘(GA)을 이용한 구조물의 동적해석 및 최적화)

  • 이영우;성활경
    • Journal of the Korean Society for Precision Engineering
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    • v.17 no.5
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    • pp.93-99
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    • 2000
  • In many dynamic structural optimization problems, the goal is to reduce the total weight of the structure without causing the resonance. Up to now, gradient informations(i.e., design sensitivity) have been used to achieve the goal. For some class of dynamic problems, especially coalescent eigenvalue Problems with multiobjective optimization, the design sensitivity analysis is too much complicated mathematically and numerically. Therefore, this article proposes a new technique fur structural dynamic modification using a mode modification method with Genetic Algorithm(GA). In GA formulation, fitness is defined based on penalty function approach. Design variables are iteratively improved by using genetic algorithm. Two numerical examples are shown, (ⅰ) a cantilevered plate, and (ⅱ) H-shaped structure. The results demonstrate that the proposed method is highly efficient.

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Study on a Method of Considering the Fluid Induced External Force in Structural Dynamic Analysis (구조동역학 해석 시 유체유동에 의한 외력을 고려하는 방법에 관한 연구)

  • Seo, Seok;Yoo, Hong-Hee
    • Proceedings of the KSME Conference
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    • pp.661-665
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    • 2000
  • A method of considering the fluid induced external force in structural dynamic analysis is presented in this study. The fluid induced pressure distribution around a structure in discrete number of orientation. and velocity is calculated by using a CFD code and tabulated as resultant forces and moments in a database. These forces and moments are interpolated and employed as external forces during the dynamic analysis of structure. The reliability and usefulness of the present method is validated by using a simple discrete system example through transient analysis. The flutter speed is obtained and compared to the analytical solution. Comparing to the method in which structural dynamic and fluid flow analyses are performed simultaneously, the present method is very efficient to save computational effort.

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Dynamic structural analysis due to dynamic motion of driving parts in low speed large diesel engine structures (저속 대형 디젤 엔진 구조물 구동부의 운동에 따른 동적 구조 해석)

  • Lee, J.H.;Jung, J.H.;Kim, J.H.
    • Proceedings of the KSME Conference
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    • pp.901-906
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    • 2001
  • Finite element method is used for the structural analysis of low speed large diesel engine structures, and the kinematic and mechanism analysis is performed to compute loads applied to the engine structures. A typical diesel engine is used as an example and static and dynamic structural analyses are demonstrated. Dynamic stress of engine is measured during the sea-trial operation of the ship.

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Vibration reduction of military vehicle frame with using structural dynamic characteristics analysis (구조 동특성 분석을 통한 군용 차량 프레임 진동 저감)

  • Lee, Sang-Jeong;Park, Jong-Beom;Park, No-Cheol;Lee, Jong-Hak;Kim, Han-Shang;Jeong, Eui-Bong
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.281-284
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    • 2014
  • Unlike ordinary vehicle chassis frame, chassis frame of military vehicle is long and that is operated in harsh driving environment in middle of war. Thus, because large dynamic loads is acting on the frame, it is important to secure the durability of the frame based on the structural dynamic characteristic analysis. The purpose of the study is that the chassis frame is optimized to secure durability of the chassis frame of the military vehicle according to the structural dynamic characteristic analysis. Also, structure optimization are performed using parametric optimization and topology optimization methods.

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Dynamic response analysis of closed loop control system for intelligent truss structures based on probability

  • Gao, W.;Chen, J.J.;Ma, H.B.;Ma, X.S.;Cui, M.T.
    • Structural Engineering and Mechanics
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    • v.15 no.2
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    • pp.239-248
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    • 2003
  • The dynamic response analysis of closed loop control system based on probability for the intelligent truss structures with random parameters is presented. The expressions of numerical characteristics of structural dynamic response of closed loop control system are derived by means of the mode superposition method, in which the randomness of physical parameters of structural materials, geometric dimensions of active bars and passive bars, applied loads and control forces are considered simultaneously. The influences of the randomness of them on structural dynamic response are inspected by several engineering examples and some significant conclusions are obtained.

Structural Optimization of Cantilever Beam in Conjunction with Dynamic Analysis

  • Zai, Behzad Ahmed;Park, M.K.;Lim, Seung-Chul;Lee, Joong-Won;Sindhu, Rashid Ali
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.397-401
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    • 2008
  • Knowledge of dynamic characteristics of structural elements often can make difference between success and failure in the design of structure due to resonance effect. In this paper an analytical model of a cantilever beam having midpoint load is considered for structural optimization. This involves creating the geometry which allows parametric study of all design variables. For that purpose optimization of cantilever beam is elaborated in order to find the optimum geometry which minimizes its volume eventually for minimum weight using ANSYS. But such geometry could be obtained by different combinations of width and height, so that it may have the same cross sectional area yet different dynamic behavior. So for optimum safe design, besides minimum volume it should have minimum vibration as well. In order to predict vibration different dynamic analyses are performed simultaneously to solve the eigenvalues problem assuming no damping initially through MATLAB simulations using state space form for modal analysis, which identifies the resonant frequencies and mode shapes belonging to the lowest three modes of vibration. And next by introducing damping effects tip displacement, bending stress and the vertical reaction force at the fixed end is evaluated under some dynamic load of varying frequency, and finally it is discussed how resonance can be avoided for particular design. Investigation of results clearly shows that only structural analysis is not enough to predict the optimum values of dimension for safe design. Potentially this technique will meet maintenance and cost goals of many organizations particularly for the application where dynamic loading is invertible and helps a lot ensuring that the proposed design will be safe for both static and dynamic conditions.

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Seismic Assessment and Performance of Nonstructural Components Affected by Structural Modeling

  • Hur, Jieun;Althoff, Eric;Sezen, Halil;Denning, Richard;Aldemir, Tunc
    • Nuclear Engineering and Technology
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    • v.49 no.2
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    • pp.387-394
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    • 2017
  • Seismic probabilistic risk assessment (SPRA) requires a large number of simulations to evaluate the seismic vulnerability of structural and nonstructural components in nuclear power plants. The effect of structural modeling and analysis assumptions on dynamic analysis of 3D and simplified 2D stick models of auxiliary buildings and the attached nonstructural components is investigated. Dynamic characteristics and seismic performance of building models are also evaluated, as well as the computational accuracy of the models. The presented results provide a better understanding of the dynamic behavior and seismic performance of auxiliary buildings. The results also help to quantify the impact of uncertainties associated with modeling and analysis of simplified numerical models of structural and nonstructural components subjected to seismic shaking on the predicted seismic failure probabilities of these systems.

A study on structural integrity and dynamic characteristic of inertial load test equipment for performance test of railway vehicle propulsion control system (철도차량 추진제어장치 성능시험을 위한 관성부하 시험설비의 구조안전성 및 동특성 평가 연구)

  • Jang, Hyung-Jin;Shin, Kwang-Bok;Lee, Sang-Hoon;Lee, Dae-Bong
    • Proceedings of the KSR Conference
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    • pp.1389-1394
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    • 2010
  • This paper describes the evaluation of structural integrity and dynamic characteristic of inertial load test equipments for performance test of railway vehicle propulsion control system. The propulsion control system of railway vehicle has to be confirmed of safety and reliability prior to it's application. Therefore, inertial load test equipments were designed through theoretical equation for performance test of propulsion control system. The structural analysis of inertial load test equipments was conducted using Ansys v11.0 and it's dynamic characteristic was evaluated the designed using Adams. The results showed that the structural integrity of inertial load test equipment was satisfied with a safety factor of 10.2. Also, the structural stability was proved by maximum dynamic displacement of 0.82mm.

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