• Title/Summary/Keyword: Force-Deflection Characteristics

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The Dynamic Characteristics of Rotating Cantilever Pipe Conveying Fluid (회전하는 유체이송 외팔 파이프의 동특성 해석)

  • 윤한익;손인수
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.13 no.1
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    • pp.26-32
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    • 2003
  • The vibrational system of this study is consisted of a rotating cantilever pipe and the flow in the pipe. The equation of motion is derived by using Lagrange equation. The influences of the rotating angular velocity and the velocities of fluid flow in the pipe have been studied on the dynamic characteristics of a rotating cantilever pipe by numerical method. The tip-amplitude of axial vibration and maximum tip-deflection of axial direction of cantilever pipe are directly proportional to the velocity of fluid and rotating angular velocity of pipe In the steady state. respectively The bending tip-amplitude of cantilever pipe is inversely proportional to the velocity of fluid in the steady state. When the rotating angular velocity is 5 rad/s, the velocity of fluid increase with increasing the natural frequency of axial vibration at second mode and third mode, but the natural frequency axial direction of first mode is decreased. The natural frequency of lateral direction is decreased due to increase of the rotating angular velocity. It identifies that the Influence of velocity of fluid give much variation lower mode of vibration in lateral direction. And the Influence of velocity of fluid give much variation higher mode of vibration in axial direction.

Experimental Study of the Quantitative Characteristics of Fluidic Thrust Vectoring Nozzle for UAV (UAV용 추력편향 노즐의 정량적 특성에 관한 실험적 연구)

  • Park, Sang-Hoon;Lee, Yeol
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.42 no.9
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    • pp.723-730
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    • 2014
  • Experimental study for supersonic co-flowing fluidic thrust vectoring control utilizing the secondary flow is performed. The characteristics of the thrust vectoring of two dimensional supersonic flow (Mach 2.0) are studied by Schlieren flow visualization and highly-accurate multi-component force measurements using the load cells. It is observed that the thrust deflection angle initially decreases and increases again forming a V-shaped variation as the pressure of the secondary flow increases. Characteristics of the performance coefficients of the system are also studied, and the detailed operating conditions for higher performance of the technique are suggested.

Characteristics of Temperature Variation to the Piezoelectric Bimorph for Vortex Flowmeter (와류 유량센서용 압전 바이몰프의 온도변화에 따른 특성)

  • Lee, Guen-Taek;Kim, Hyung-Sun;Im, Jong-In
    • Korean Journal of Materials Research
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    • v.17 no.5
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    • pp.289-292
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    • 2007
  • Although piezoelectric bimorph that is using as the sensor in medical and industrial measurement has large displacement, it has problems including efficiency in generating force, energy convergence, and response. Its application is being limited based on the change in resonance frequency with temperature. In this study, to overcome the disadvantages, PZT piezoelectric ceramics was prepared and produced a parallel type piezoelectric bimorphs. In addition, by using the finite element method. the configuration of piezoelectric bimorph was designed and the displacement of the bimorph based on applied electric pressure and the wave pattern were measured. By analyzing the resonance characteristics of the bimorph in the temperature range of $-60{\sim}80^{\circ}C$, an attempt was made to study the operational characteristics and temperature reliability of vortex flowmeter sensor. As a result, the resonance frequency of the bimorph was gradually increased with the temperature from $-60{\sim}80^{\circ}C$. The deflection of the bimorph was found to strongly depend on both the applied electric field waveform and the environmental temperature.

Design and Control of a MR Shock Absorber for Electronic Control Suspension (전자제어 현가장치를 위한 MR 쇽 업소버의 설계 및 제어)

  • Sung, Kum-Gil;Choi, Seung-Bok
    • Journal of the Korean Society for Precision Engineering
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    • v.28 no.1
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    • pp.31-39
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    • 2011
  • This paper presents design and control of a quarter-vehicle magneto-rheological (MR) suspension system for ECS (electronic control suspension). In order to achieve this goal, MR shock absorber is designed and manufactured based on the optimized damping force levels and mechanical dimensions required for a commercial mid-sized passenger vehicle. After experimentally evaluating dynamic characteristics of the manufactured MR shock absorber, the quarter-vehicle MR suspension system consisting of sprung mass, spring, tire and the MR shock absorber is constructed in order to investigate the ride comfort and driving stability. After deriving the equations of the motion for the proposed quarter-vehicle MR suspension system, the skyhook controller is then implemented for the realization of quarter-vehicle MR suspension system. In order to present control performance of MR shock absorber for ECS, ride comfort and driving stability characteristics such as vertical acceleration of sprung mass and tire deflection are experimentally evaluated under various road conditions and presented in both time and frequency domain.

A Study on Flow Characteristics of Fountain-pen Nano-Lithography with Active Membrane Pumping (능동적 박막 펌핑에 의한 파운틴 펜 나노 리소그래피 유동 특성에 관한 연구)

  • Lee Jin-Hyoung;Lee Young-Kwan;Lee Sung-Kun;Lee Suk-Han;Kim Youn-Jea;Kim Hun-Mo
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.30 no.8 s.251
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    • pp.722-730
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    • 2006
  • In this study, the flow characteristics of a FPN (Fountain Pen Nano-Lithography) using active membrane pumping are investigated. The FPN has integrated chamber, micro channel, and high capacity reservoir for continuous ink feed. The most important aspect in this probe provided control of fluid injection using active membrane pumping in chamber. The flow rates in channel by capillary force are theoretically analyzed, including the control of the mass flow rates by the deflection of the membrane. The above results are compared with the numerical simulations that calculated by commercial code, FLUENT. The velocity of the fluid in micro channel shows linear behaviors. And the mass flows are proportional to the second order function of the pumping pressure that is imposed to the membrane.

A Study on LIT Girder Performance Improvement (LIT 거더 성능 개선에 대한 연구)

  • Kim, Sung;Park, Sungjin
    • Journal of Urban Science
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    • v.11 no.2
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    • pp.19-24
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    • 2022
  • Conventional RC beams for crossing small and medium-sized rivers do not have a cross-sectional area, so the floating debris is accumulated and disasters such as damage to bridges occur. To improve this, the PSC method was invented. However, this also had problems such as transverse curvature, increase in dead weight due to cross-sectional shape, and negative moment generated during serialization, so it was necessary to develop a new type of girder. Therefore, it was intended to propose a LIT(Leton Interaction Thrust) girder bridge that is safer and has better performance than the conventional PSC girder with improved section efficiency. Unlike existing girder bridges, the LIT girder has the feature that the change in the strands of the entire girder occurs only in the vertical direction when the first tension is applied because the tendon arrangement is symmetrical by applying the raised portion. In addition, slab continuation generates a secondary moment that is advantageous to the continuous point, effectively controlling the negative moment and preventing the corrosion of the tendon. The dimensions of the cross section were determined, and the arrangement of the strands was designed to conduct structural analysis and detailed analysis. As a result of the structural analysis, the stress of the girder showed results within the allowable compressive stress, and the deflection showed the result within the allowable deflection. showed results. In addition, a detailed analysis was performed to examine the stress distribution around the girder body and the anchorage area and the stress distribution of the embossed portion, and as a result, the stress of the girder body due to the tension force showed a stable level.

A Study on Low Velocity Impact Characteristics of DP 780 High Strength Steel Sheet with Thickness of 1.7 mm on the Free Boundary Condition Using Three-Dimensional Finite Element Analysis (3 차원 유한요소해석을 이용한 자유경계조건에서의 두께 1.7 mm DP780 고강도 강판의 저 속 충격 특성 분석)

  • Ahn, Dong-Gyu;Nam, Gyung-Heum;Seong, Dae-Yong;Yang, Dong-Yol;Lim, Ji-Ho
    • Journal of the Korean Society for Precision Engineering
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    • v.27 no.11
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    • pp.46-56
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    • 2010
  • The present research works investigated into the low velocity impact characteristics of DP 780 high strength steel sheet with 1.7 mm in thickness subjected to free boundary condition using three-dimensional finite element analysis. Finite element analysis was carried out via ABAQUS explicit code. Hyper-elastic model and the damping factor were introduced to improve an accuracy of the FE analysis. An appropriate FE model was obtained via the comparison of the results of the FE analyses and those of the impact tests. The influence of the impact energy and nose diameter of the impact head on the force-deflection curves, impact time, absorption characteristics of the impact energy, deformation behaviours, and stress-strain distributions was quantitatively examined using the results of FE analysis. The results of the FE analysis showed that the absorption rate of impact energy lies in the range of the 70.7-77.5 %. In addition, it was noted that the absorption rate of impact energy decreases when the impact energy increases and the nose diameter of the impact head decreases. The local deformation of the impacted region was rapidly increased when the impact energy was larger than 76.2 J and the nose diameter was 20 mm. A critical impact energy, which occur the instability of the DP780, was estimated using the relationship between the plastic strain and the impact energy. Finally, characteristics of the plastic energy dissipation and the strain energy density were discussed.

A Study on a Foxtail Electrostatic Microactuator with a High Resolution (고해상도의 Foxtail형 정전력 마이크로구동기에 대한 연구)

  • Kim Man-Geun;Kim Young-Yun;Jo Kyoung-Woo;Lee Jong-Hyun
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.06a
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    • pp.1198-1201
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    • 2005
  • A new foxtail actuator driven by V-shape beam deflection using electrostatic force has been designed, fabricated and characterized for nano-resolution manipulators. The proposed foxtail mechanism was implemented using a pair of electrostatic actuators and a pair of holding actuators, which was analyzed based on the electromechanically coupled motion of voltage - displacement relation. The proposed actuator was fabricated onto Silicon-on-Insulator (SOI) wafer and its stepping characteristics were measured by micro optical interferometer consisting of integrated micromirror and optical fiber. The fabricated foxtail microactuator was successfully operated from 1nm to 76nm, and the magnitude of step displacement was controllable up from 26nm/cycles to 53nm/cycle by changing the voltage.

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A Study on Dynamic Behaviors of Steel Plate Girder bridge with Applying External Post-Tensioning Method (외부 후긴장 공법 적용에 따른 무도상 판형교의 동적거동 분석)

  • Choi, Dong-Ho;Choi, Jung-Youl;Choi, Jun-Hyeok;Park, Yong-Gul
    • Journal of the Korean Society for Railway
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    • v.9 no.2 s.33
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    • pp.160-168
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    • 2006
  • The major objective of this study is to investigate the effects and application of external post-tensioning method far steel plate girder bridge. It analyzed the mechanical behaviors of steel plate girder bridge with applying external post-tensioning on the finite element analysis, field test and laboratory test fur the lateral dynamic characteristics. As a result, the reinforcement of steel plate girder bridge the external post-tensioning method are obviously effective for the lateral dynamic response which is non-reinforced. The analytical and experimental study are carried out to investigate the post-tension force decrease lateral acceleration and deflection on steel plate girder bridge for serviceability. And the external post-tensioning method reduce dynamic maximum displacement(about $10{\sim}24%$), the increase of dynamic safety is predicted by adopting external post-tensioning method. From the dynamic test results of the servicing steel plate girder bridge, it is investigated that the change degree of natural frequency is very low with applying the external post-tensioning method The servicing steel plate girder bridge with external post-tensioning has need of the reasonable reinforcement measures which could be reducing the effect of lateral dynamic behavior that degradation phenomenon of structure by an unusual response characteristic and a drop durability.

Self-Tuning Gain-Scheduled Skyhook Control for Semi-Active Suspension Systems: Implementation and Experiment (반능동 현가시스템용 자기동조 게인조절형 스카이훅 제어기의 구현 및 실험)

  • Hong, Kyung-Tae;Huh, Chang-Do;Hong, Keum-Shik
    • Journal of Institute of Control, Robotics and Systems
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    • v.8 no.3
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    • pp.199-207
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    • 2002
  • In this paper, a self-tuning gain-scheduled skyhook control for semi-active suspension systems is investigated. The dynamic characteristics of a continuously variable damper including electro-hydraulic pressure control valves is analyzed. A 2-d.o.f. time-varying quarter-car model that permits variations in sprung mass and suspension spring coefficient is considered. The self-tuning skyhook control algorithm proposed in this paper requires only the measurement of body acceleration. The absolute velocity of the sprung mass and the relative velocity of the suspension deflection are estimated by using integral filters. The skyhook gains are gain-scheduled in such a way that the body acceleration and the dynamic tire force are optimized. An ECU prototype is discussed. Experimental results using a 1/4-ear simulator are discussed. Also, a suspension ECU prototype targeting real implementation is provided.