• 제목/요약/키워드: stiffness reduction

검색결과 834건 처리시간 0.025초

저탄성 베이스플레이트 패드 적용에 따른 포장궤도 노반에서의 전달하중 저감에 관한 연구 (A Study on Transferred Load Reduction on Paved Track Roadbed with Low Elastic Base Plate Pad)

  • 이일화;강윤석;이희업
    • 대한토목학회논문집
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    • 제28권3D호
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    • pp.399-405
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    • 2008
  • 포장궤도는 기존선의 유지보수 노력을 절감하기 위하여 개발되고 있다. 이 중 베이스플레이트 저탄성패드는 궤도 전체의 지지강성을 결정하는 구성품으로서 궤도의 응력-변위특성, 동적응답, 피로특성 등에 가장 큰 영향을 미친다. 따라서 저탄성패드의 적용은 궤도전체의 내구성과 안정성에 미치는 영향이 크다고 할 수 있다. 본 논문에서는 저탄성패드의 적용으로 인하여 획득되는 효과 중 노반에 전달되는 열차하중의 저감에 대한 연구를 수행하였다. 이를 위하여 패드스프링계수별 정적해석과 실물반복재하시험을 수행하고 그 결과를 비교 분석하여 저탄성패드의 하중 전달특성을 파악하였으며 전달하중 저감효과를 검토하였다.

자동차 엔진 크랭크축의 진동해석을 위한 자유도 저감법 개발에 관한 연구 (A Proposed Reduction Method for Vibatiton Analysis of Automobile Engine Crakshfts)

  • 최명진
    • 한국생산제조학회지
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    • 제5권2호
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    • pp.29-37
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    • 1996
  • High speed engines with high power are increasingly on demands and almost engines employ crankshafts Such problems as bending and torsional vibrations become the point at issue in crankshaft analysis and design. In this study to overcome the diffiiculty with the large amount of computation in finite element vibration analysis of a crankshaft, a reduction method based on influence coefficient and lumped parameter is presented. which reduces the computation amount effectively and can be used in vibrational analysis and design of any types of crankshafts Crank journal and pinparts are meodelled as elements with 6degrees of freedom per node. Crank web part is modelled using equivalent mass and stiffness matices . based up on lumped parameter and influence coefficient respectively to reduce total degrees of freedom considerablely. To confirm the scheme of the study the results are compared with the known data and they are coincident. Also a simple crankshaft is designed and manufactured for experiments. The calculated results using reduction method and the experimental results agree well The scheme of this study can be utilized in evaluation results agree well. The calculated result are compared with the known data and they are coincident. Also a simple crankshaft is designed and manufactured for experiments. The calculated results using reduction method and the experimental results agree well. The scheme of this study can be utilized in evaluation and development of high speed engine.

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항공기용 하니콤 트림판넬의 다채널 능동제어 (Multichannel Active Control of Honeycomb Trim Panels for Aircrafts)

  • 홍진숙
    • 한국소음진동공학회논문집
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    • 제16권12호
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    • pp.1252-1261
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    • 2006
  • This paper summarizes theoretical work on the multichannel decentralized feedback control of sound radiation from aircraft trim panels using piezoceramic actuators. The aircraft trim panels are generally honeycomb structures designed to meet the design requirement of low weight and high stiffness. They are resiliently-mounted to the fuselage for the passive reduction of noise transmission. It is motivated by the localization of reduction in vibration of single channel active trim panels. 12-channel decentralized feedback control systems are investigated in terms of the reduction of noise and vibration for three configurations of sensor actuator pairs. Local coupling of the closely-spaced sensor and actuator pairs was modeled using single degree of freedom systems. The multichannel control system is characterized using the state-space model. For the stability point of view, the relative stability or robustness is evaluated by comparing the real part of eigenvalues of the system matrix for the three configurations. The control performance is also evaluated and compared for the three configurations. It is found that the multichannel system can lead to the globalization of the reduction in vibration and radiated noise. It does not appear to yield a significant improvement in the vibration because of decreased gain margin. However, the reduction in the radiated noise is remarkably improved due to the variation of the vibration pattern with the actuation configurations.

Krylov subspace-based model order reduction for Campbell diagram analysis of large-scale rotordynamic systems

  • Han, Jeong Sam
    • Structural Engineering and Mechanics
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    • 제50권1호
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    • pp.19-36
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    • 2014
  • This paper focuses on a model order reduction (MOR) for large-scale rotordynamic systems by using finite element discretization. Typical rotor-bearing systems consist of a rotor, built-on parts, and a support system. These systems require careful consideration in their dynamic analysis modeling because they include unsymmetrical stiffness, localized nonproportional damping, and frequency-dependent gyroscopic effects. Because of this complex geometry, the finite element model under consideration may have a very large number of degrees of freedom. Thus, the repeated dynamic analyses used to investigate the critical speeds, stability, and unbalanced response are computationally very expensive to complete within a practical design cycle. In this study, we demonstrate that a Krylov subspace-based MOR via moment matching significantly speeds up the rotordynamic analyses needed to check the whirling frequencies and critical speeds of large rotor systems. This approach is very efficient, because it is possible to repeat the dynamic simulation with the help of a reduced system by changing the operating rotational speed, which can be preserved as a parameter in the process of model reduction. Two examples of rotordynamic systems show that the suggested MOR provides a significant reduction in computational cost for a Campbell diagram analysis, while maintaining accuracy comparable to that of the original systems.

플랩 블레이드를 이용한 조류 터빈의 부하 저감에 대한 연구 (Study on Load Reduction of a Tidal Steam Turbine Using a Flapped Blade)

  • 정다솜;고진환
    • Ocean and Polar Research
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    • 제42권4호
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    • pp.293-301
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    • 2020
  • Blades of tidal stream turbines have to sustain many different loads during operation in the underwater environment, so securing their structural safety is a key issue. In this study, we focused on periodic loads due to wave orbital motion and propose a load reduction method with a blade design. The flap of an airplane wing is a well-known structure designed to increase lift, and it can also change the load distribution on the wing through deflection. For this reason, we adopted a passive flap structure for the load reduction and investigated its effectiveness by an analytical method based on the blade element moment theory. Flap torsional stiffness required for the design of the passive flap can be obtained by calculating the flap moment based on the analytic method. Comparison between a flapped and a fixed blade showed the effect of the flap on load reduction in a high amplitude wave condition.

열차의 곡선주행능 해석에 관한 연구 (A Study on the Analysis of Curving Performance of Railway Vehicle)

  • 김도중;박삼진
    • 한국기계연구소 소보
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    • 통권14호
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    • pp.101-110
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    • 1985
  • Kyung-p-1 main line is characterized by its curves radii of which are considerably small. It is essential for running time reduction of train to improve capabilities of curve negotiation. This improvement can be achieved by designing a bogie with flexible suspension system. The effect of the improvement is mainly concerned in the primary yaw stiffness of bogie suspension. This paper gives a linear analysis for the motion of railway vehicle on curved track and gives also computer simulation results for Semaul Train. The results introduce a conclusion that the primary yaw stiffness of Semaul train is too rigid to be self-steering on Kyung-pu main line curves.

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가변속 왕복동형 압축기 본체의 동적 거동 해석 (Dynamic Behavior Analysis of a Reciprocating Compressor Body with Variable Rotating Speed)

  • 김태종
    • 한국소음진동공학회논문집
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    • 제11권8호
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    • pp.374-383
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    • 2001
  • A reciprocating compressor unit with variable rotating speed driven by BLDC motor is mounted Inside hermetic chamber on an internal suspension composed of 4 roil springs and a discharge pipe. A method for predicting the dynamic behavior of compressor body is required for a reduction of transmitted vibrations. The mechanical characteristics of spring and discharge pipe stiffness properties have been obtained from experimental tests and mass moment of inertia of the compressor body iron CAD. To confirm the vibration model for the compressor body, free vibration analyses are performed with theoretical and experimental methods. results for analytical investigations on the dynamic behavior of the compressor body and the transmitted forces to the hermetic chamber through the suspension elements are Presented.

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HLA를 장착한 직접 구동형 OHC 밸브 트레인 시스템의 마찰 특성 해석 (Analysis of Frictional Characteristics of Direct-Acting OHC Valve Train System Equipped with HLA)

  • 지유철;조명래;한동철;최재권
    • 한국자동차공학회논문집
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    • 제6권3호
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    • pp.78-87
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    • 1998
  • A dynamic model of direct-acting OHC valve train system has been used to determine the load conditions in the system. The modified equations for calculating the friction forces between cam and HLA, and at a camshaft bearing have been defined considering the lubrication conditions. Then, to understand the frictional characteristics in the system, a parameter study has been performed. As the results of the analysis, valve spring stiffness and preload have great effects on the friction in the system, but the effects of other parameters are negligible. So, how to design the valve train system with respect to the reduction of friction is to minimize the valve spring stiffness and preload in the limit of satisfying the dynamic constraints.

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복합재료를 이용한 경량 공작기계 구조물 제작에 관한 연구 (Manufacture of light-weight machine tool structures using composite materials)

  • 서정도;이대길;김학성;김종민;최진경
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2001년도 춘계학술대회논문집C
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    • pp.189-196
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    • 2001
  • Machine tools of high-speed and high-precision are required for various fields of industry such as semiconductor, automobile, mold fabrication and so on. Light-weight machine tool structure is essential for reduction of production time through rapid transportation. Also, high damping capacity of the structure is required to obtain precise products without vibration during manufacturing. Composite materials have high potential for machine tool structures due to its high specific stiffness and good damping characteristics. In this study, the design and the manufacture of a hybrid machine tool structure using composite materials was attempted and the damping capacity was investigated experimentally.

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공기 베어링 개념을 이용한 디스크 진동 저감 연구 (Disk Vibration Suppression with Air Bearing Concept)

  • 최의곤;임윤철
    • Tribology and Lubricants
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    • 제20권4호
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    • pp.197-203
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    • 2004
  • As the rotational speed and the track density are increased, the vibration of disk/spindle system becomes critical issue in order to reduce the track mis-registration. In this work, we propose a simple inclined air bearing (20${\times}$20 mm) system which is located very near to the rotating poly-carbonate disk, and investigate suppressing effect for the disk vibration mode (0,0) both experimentally and numerically. We find dynamic stiffness and damping coefficients of air bearing and then apply those values to the disk vibration analysis. Numerical results show about 10 percent difference comparing to the experimental results. Also we investigate the reduction of disk vibration and power consumption with two different kinds of inclined bearing for the normal disk drive system experimentally. We find inclined air bearing can reduce about 30 percents of the transverse disk vibration.