• Title, Summary, Keyword: Structural Characteristic Analysis

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Structural Characteristic Analysis on the Hydrostatic Guide Way and Feeding System of a High-Precision Centerless Grinder for Machining Ferrules (페룰 가공용 초정밀 무심 연삭기의 유정압 안내면 및 이송계에 대한 구조 특성 해석)

  • Kim, Seok-Il;Park, Chun-Hong;Cho, Soon-Joo
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.28 no.7
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    • pp.896-903
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    • 2004
  • This paper proposes the structural characteristic analysis and evaluation on the hydrostatic guide way and feeding system of a high-precision centerless grinder for machining ferrules. In order to realize the required accuracy of ferrules with sub-micron order, the axial stiffness and motion accuracy of feeding system have to become higher level than those of existing centerless grinders. Under these points of view, the physical prototype of feeding system composed of steel bed, hydrostatic guide way and ballscrew feeding mechanism is designed and manufactured for trial. Experimental results show that the axial and vertical stiffnesses of the physical prototype are very low as compared with those design values. In this paper, to reveal the cause of these stiffness difference, the structural deformations on the virtual prototype of feeding system are analyzed based on the finite element method under experimental conditions. The simulated results illustrate that the deformation of front ballscrew support-bearing bracket is the main cause of reduction in the axial stiffness of feeding system, and the deflection of bed structure and the bending deformation of hydrostatic guide rails are the main causes of reduction in the vertical stiffness of feeding system.

FE Vibration Analysis and Structural Modification of Slim Type Optical Disk Drive (유한요소 해석을 통한 슬림형 광디스크 드라이브의 진동해석 및 구조 동특성 변경)

  • Kim, Kyung-Tae;Lim, Seung-Ho;Lee, Yong-Hyun;Park, No-Cheol;Park, Young-Pil;Lee, In-Hwan;Lee, Han-Baek;Cha, Ik-Joo
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.1284-1287
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    • 2007
  • Recently, the need for slim type optical disk drive(ODD) has increased with popularization of lightweight notebook. Because of its lightweight and small structure, slim type ODD has low structural stiffness and it is weak to high-speed disk vibration. In this paper, Finite Element(FE) Model of slim type ODD is constructed and verified by experimental modal analysis. Additionally, sensitivity analysis is performed about structural parameters. As a result of sensitivity analysis, improved characteristic is verified by experiments using a sample of new model.

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A Study of Noise Characteristics Induced by Slab Vibration for the Elevated Railway Station (선하역사의 슬래브 진동에 의한 소음방사 특성에 관한 연구)

  • Kim, Jin-Ho;Jang, Dongdoo;Ji, Yong-Soo
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.16 no.5
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    • pp.3557-3566
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    • 2015
  • In the case of elevated railway station in which railway is connected with superstructure of station, vibration and noise level is relatively higher than those of general structure type station due to structural characteristic which transmits vibration directly. Therefore, characteristic understanding of structural vibration and accompanying structure cause noise and establishment of reduction plan through the results are in need. Test and analysis are performed in this research to consider correlativity between structural vibration and accompanying structure cause noise when external forces are applied on standard slab and floating slab which is able to isolate vibration. By producing and loading on standard and floating slab, vibration and noise response are measured while simulation using numerical analysis, finite element method and SEA method is performed. The results about structural dynamic behavior of slab, correlativity between structural vibration and noise, reduction performance of floating slab is deduced through the analysis of tests.

Shape Optimization of the Lower Control Arm using the Characteristic Function and the Fatigue Analysis (특성함수와 피로해석을 이용한 로워컨트롤암의 형상최적설계)

  • Park Youngchul;Lee Donghwa
    • Transactions of the Korean Society of Automotive Engineers
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    • v.13 no.1
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    • pp.119-125
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    • 2005
  • The current automotive is seeking the improvement of performance, the prevention of environmental pollution and the saving of energy resources according to miniaturization and lightweight of the components. And the variance analysis on the basis of structure analysis and DOE is applied to the lower control am. We have proposed a statistical design model to evaluate the effect of structural modification by performing the practical multi-objective optimization considering weight, stress and fatigue lift. The lower control arm is performed the fatigue analysis using the load history of real road test. The design model is determined using the optimization of acquired load history with the fatigue characteristic. The characteristic function is made use of the optimization according to fatigue characteristics to consider constrained function in the optimization of DOE. The structure optimization of a lower control arm according to fatigue characteristics is performed. And the optimized design variable is D=47 m, T=36mm, W=12 mm. In the real engineering problem of considering many objective functions, the multi-objective optimization process using the mathematical programming and the characteristic function is derived an useful design solution.

Dynamic Characteristic Analyses of a Bearingless Helicopter Rotor Systems (무베어링 헬리콥터 로터 시스템의 동특성 해석)

  • Kee, Young-Jung;Yun, Chul-Yong;Kim, Seung-Ho
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.52-56
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    • 2011
  • Recently, KARI(Korea Aerospace Research Institute) has been developing a modern 11.5m diameter four bladed bearingless main rotor system, and this rotor system can be used for 7,000lb class helicopter. Flexbeam and torque tube can be considered as the key structural components, and large elastic twist of flexbeam induced by pitch control motion of torque tube can influence the nonlinear aeroelastic behavior. In this paper, the dynamic characteristic analysis results of bearingless rotor system were presented. In order to construct a input model and validate the analysis procedures, calculated results using the comprehensive helicopter analysis program CAMRAD II were compared with the measured natural frequencies and lag damping data from small-scale wind tunnel test. Next, the analysis model was extended to a full-scale model, and the dynamic analysis results were presented.

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Dynamic Characteristic Analyses of a Bearingless Helicopter Rotor System (무베어링 헬리콥터 로터 시스템의 동특성 해석)

  • Kee, Young-Jung;Yun, Chul-Yong;Kim, Doeg-Kwan;Kim, Seung-Ho
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.22 no.2
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    • pp.187-192
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    • 2012
  • Recently, KARI(Korea Aerospace Research Institute) has been developing a modern 11.5 m diameter four bladed bearingless main rotor system, and this rotor system can be used for 7,000 lb class helicopter. Flexbeam and torque tube can be considered as key structural components, and large elastic twist of flexbeam induced by pitch control motion of torque tube can influence the nonlinear aeroelastic behavior. In this paper, the dynamic characteristic analysis results of bearingless rotor system were presented. In order to construct a input model and validate the analysis procedures, calculated results using the comprehensive helicopter analysis program CAMRAD II were compared with the measured natural frequencies and lag damping data from small-scale wind tunnel test. Next, the analysis model was extended to a full-scale model, and the dynamic analysis results were presented.

Repair and Retrofit of Fatigue crack for Curved Girder Bridge (곡선 강교량 피로균열 보수.보강방안)

  • Park, Jin-Eun;Kyung, Kab-Soo;Kwon, Soon-Cheol;Lee, Hee-Hyun
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.50-55
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    • 2008
  • In order to investigate and estimate the cause of fatigue crack occurred to curved girder bridge that is used during 20 years, in this study, filed tests to obtain the characteristic of stress hysteresis were performed under the real traffic flows. From these test results, we analyzed the cause of fatigue crack for various fatigue crack patterns. Also, the characteristic of structural behavior for the curved girder bridge were examined from the FE analysis. In addition, to retrofit various fatigue cracks occurred in the bridge, FE analyses considering the characteristics of crack patterns were performed and retrofitting methods were suggested.

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Simplified computational methodology for analysis and studies on behaviour of incrementally launched continuous bridges

  • Sasmal, Saptarshi;Ramanjaneyulu, K.;Srinivas, V.;Gopalakrishnan, S.
    • Structural Engineering and Mechanics
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    • v.17 no.2
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    • pp.245-266
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    • 2004
  • Incremental launching method is one of the highly competitive techniques for construction of concrete bridges. It avoids costly and time consuming form work and centralizes all construction activities in a small casting yard, thus saving in cost and time against conventional bridge construction. From the quality point of view, it eliminates the uncertainty of monolithic behaviour by allowing high repetitiveness and industrial environment. But, from analysis and design point of view, the most characteristic aspect of incrementally launched bridges is that, it has to absorb the stresses associated with the temporary supports that are gradually taken on by the deck during its launch. So, it is necessary to analyse the structure for each step of launching which is a tedious and time consuming process. Effect of support settlements or temperature variation makes the problem more complex. By using transfer matrix method, this problem can be handled efficiently with minimal computational effort. This paper gives insight into method of analysis, formulation for optimization of the structural system, effect of support settlement and temperature gradient, during construction, on the stress state of incrementally launched bridges.

Probabilistic stability analysis of underground structure using stochastic finite element method

  • Na, Sang-Min;Moon, Hyun-Koo
    • 한국지구물리탐사학회:학술대회논문집
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    • pp.192-197
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    • 2003
  • It can be said that rock mass properties are characterized not by a mean value but by values with variation due to its characteristic uncertainty. This characteristic is one of the most important parts for the design of underground structures, but yet to be fully examined. Stochastic finite element method (SFEM) has been developed in order to take the randomness of structural systems into account. Using SFEM, the response variability of structural system can be obtained and it leads probabilistic stability of structure to be analyzed. In this study, displacements response variability of circular opening with hydrostatic stress field are analyzed in terms of rock mass properties having a certain mean and a standard deviation using the SFEM. The analyzed response variability shows that the necessity of probabilistic stability analysis of underground structures using reliable mean value and standard deviation of deformation modulus.

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Development of Probabilistic-Fuzzy Model for Seismic Hazard Analysis (지진예측을 위한 확률론적퍼지모형의 개발)

  • 홍갑표
    • Computational Structural Engineering
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    • v.4 no.3
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    • pp.107-115
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    • 1991
  • A probabilistic-Fuzzy model for seismic hazard analysis is developed. The proposed model is able to reproduce both the randomness and the imprecision in conjunction with earthquake occurrences. Results-of this research are (a) membership functions of both peak ground accelerations associated with a given probability of exceedance and probabilities of exceedance associated with a given peak ground acceleration, and (b) characteristic values of membership functions at each location of interest. The proposed probabilistic-fuzzy model for assessment of seismic hazard is successfully applied to the Wasatch Front Range in Utah in order to obtain the seismic maps for different annual probabilities of exceedance, different peak ground accelerations, and different time periods.

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