• Title/Summary/Keyword: vibration performance

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Development of ETMD for Improving TMD Control Performance (TMD 제어성능 개선을 위한 ETMD 개발)

  • Jeon, Seung gon
    • Journal of the Earthquake Engineering Society of Korea
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    • v.26 no.4
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    • pp.157-164
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    • 2022
  • The TMD has a simpler structure than other vibration control devices and shows excellent control performance for the standardized vibration occurring in the structure. However, when the vibration cycle of the structure coincides with the vibration cycle of the TMD due to the sudden external loads, the off-tuning occurs, which threatens the structure while increasing the vibration width of the TMD. Therefore, Electromagnetic Tuned Mass Damper (ETMD) was developed as a semi-active TMD that prevents off-tuning while exhibiting excellent control performance like TMD. To verify the control performance of the developed ETMD, the bending behavior control performance evaluation experiment using a simple beam bridge was performed. The experimental method compared the mutual control power by experimenting with the existing TMD method and the developed ETMD under nine excitation frequency conditions. As a result, it was confirmed that the control effect of ETMD was about 4.85% higher than that of TMD at 3.02Hz, which generates the maximum displacement in the simple beam bridge. Also, the off-tuning occurred in some excitation conditions when using TMD, although the off-tuning did not occur when using ETMD. Therefore, the excellent control performance of the ETMD developed in this study was verified.

Analysis of Structural Stability and Optical Performance for Optical Equipment During In-flight Vibration (항공기 진동에 대한 광학 탑재 장비 구조 안정성 및 광학 성능 분석)

  • Jo, Mun Shin;Kim, Sang Won
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.41 no.9
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    • pp.897-904
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    • 2017
  • Optical equipment consists of various components, and a detector is mounted and operated on aircraft, tanks, and warships for target detection and classification. The structural stability and optical performance of aeronautical optical equipment operated at several kilometers of altitude are degraded owing to vibration generated in the aircraft. It is necessary to verify the structural stability and optical performance requirements of the equipment in vibration environment conditions during the design phase. In this study, vibration environment conditions were analyzed using a test standard and the measurements of the vibration generated in aircraft. The conditions were classified as endurance and operating vibration conditions for structural stability and optical performance verification, respectively. The structural stability was verified according to natural frequency analysis, response analysis for the endurance vibration condition, and static analysis. The optical performance was verified by applying the vibration response analysis results to the optical design/analysis program.

Vibration Control of Tower Structure under Wind Load (풍하중에 의한 타원형 구조물의 진동 제어)

  • Hwang Jae-Seung;Kim Yun-Seok;Joo Seok-Jun
    • Proceedings of the KSME Conference
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    • 2002.08a
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    • pp.427-430
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    • 2002
  • The present parer outlines the system identification and vibration control performance of air traffic control tower of Yangyang international airport with tuned mass damper(TMD). From the free vibration test, natural frequency, damping ratio and mode shape of tower are obtained and these values are compared with the values from numerical analysis. In the vibration control test to evaluate the vibration control performance, equivalent damping ratio increased by tuned mass damper are obtained in case the TMD is operated as passive mode. Damping ratio of tower evaluated from free vibration test is about $1.0{\%}$. It is very low value than damping ratio recommended in general code. Damping ratio of passive mode is about $5{\%}$. These equivalent damping ratio increased by TMD is enough to enhance the serviceability of tower structure under wind load.

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Eight-node field-consistent hexahedron element in dynamic problems

  • Rajendran, S.;Prathap, G.
    • Structural Engineering and Mechanics
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    • v.8 no.1
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    • pp.19-26
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    • 1999
  • Superior performance of field consistent eight-node hexahedron element in static bending problems has already been demonstrated in literature. In this paper, its performance in free vibration is investigated. Free vibration frequencies of typical test problems have been computed using this element. The results establish its superior performance in free vibration, particularly in thin plate application and near incompressibility regimes, demonstrating that shear locking, Poisson's stiffening and volumetric locking have been eliminated.

A Study on Active Vibration Isolation Using Electro-Magnetic Actuator (전자기력을 이용한 능동제진에 관한 연구)

  • 손태규;김규용;박영필
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.18 no.5
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    • pp.1169-1181
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    • 1994
  • Vibration isolation of mechanical systems, in general, is achieved through passive or active vibration isolators. Passive vibration isolator has an inherenrt performance limitation. Whereas, active vibration isolator provides significantly superior vibration-isolation performance at the cost of energy sources and sensors. Recently, in many cases, such as suspension system, precision machinery ... etc, active isolation system outweighs its limitation. Therefore, many studies, researches, and applications are carried out in this field. In this study, vibration-isolation characteristics of an active vibration control system using electromagnetic force actuator are investigated. Several control algorithms including optimal, feedforward are used for active vibration isolation. From the experimental results of each algorithm, effective control algorithms for this active vibration-isolation system are proposed.

Experimental Performance Evaluation of MR Damper for Integrated Isolation Mount (통합제진마운트용 MR 댐퍼의 실험적 성능 평가)

  • Seong, Min-Sang;Choi, Seung-Bok;Kim, Cheol-Ho;Lee, Hong-Ki;Baek, Jae-Ho;Han, Hyun-Hee
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2010.10a
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    • pp.65-70
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    • 2010
  • This paper presents experimental performance evaluation of a magnetorheological (MR) damper for integrated isolation mount for ultra-precision manufacturing system. The vibration sources of the ultra-precision manufacturing system can be classified as follows: the one is the environmental vibration from the floor and the other is the transient vibration occurred from stage moving. The transient vibration occurred from the stage moving has serious adverse effect to the process because the vibration scale is quite larger than other vibrations. Therefore in this research, a semi-active MR damper, which can control the transient vibration, is adopted. Also the stage needs to be isolated from tiny vibrations from the floor. For this purpose, a dry-frictionless MR damper is required. In order to achieve this goal, a novel type of MR damper is originally designed and manufactured in this work. Subsequently, the damping force characteristics of MR damper are evaluated by simulation and experiment. In addition, the vibration control performance of the MR damper associated with the stage mass is evaluated.

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Active Vibration Control of Smart Hull Structure in Underwater Using Micro-Fiber Composite Actuators (MFC 작동기를 이용한 수중 Hull 구조물의 능동 진동 제어)

  • Kwon, Oh-Cheol;Sohn, Jung-Woo;Choi, Seung-Bok
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2008.11a
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    • pp.466-471
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    • 2008
  • Structural vibration and noise are hot issues in underwater vehicles such as submarines for their survivability. Therefore, active vibration and noise control of submarine, which can be modeled as hull structure, have been conducted by the use of piezoelectric materials. Traditional piezoelectric materials are too brittle and not suitable to curved geometry such as hull structures. Therefore, advanced anisotropic piezoceramic actuator named as Macro-Fiber Composite (MFC), which can provide great flexibility, large induced strain and directional actuating force is adopted for this research. In this study, dynamic model of the smart hull structure is established and active vibration control performance of the smart hull structure is evaluated using optimally placed MFC. Actuating performance of MFC is evaluated by finite element analysis and dynamic modeling of the smart hull structure is derived by finite element method considering underwater condition. In order to suppress the vibration of hull structure, Linear-Quadratic-Gaussian (LQG) algorithm is adopted. After then active vibration control performance of the proposed smart hull structure is evaluated with computer simulation and experimental investigation in underwater. Structural vibration of the hull structure is decreased effectively by applying proper control voltages to the MFC actuators.

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Experimental Performance Evaluation of MR Damper for Integrated Isolation Mount (통합제진마운트용 MR 댐퍼의 실험적 성능 평가)

  • Seong, Min-Sang;Choi, Seung-Bok;Kim, Cheol-Ho;Lee, Hong-Ki;Baek, Jae-Ho;Han, Hyun-Hee;Woo, Je-Kwan
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.20 no.12
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    • pp.1161-1167
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    • 2010
  • This paper presents experimental performance evaluation of a magnetorheological(MR) damper for integrated isolation mount for ultra-precision manufacturing system. The vibration sources of the ultra-precision manufacturing system can be classified as follows: the one is the environmental vibration from the floor and the other is the transient vibration occurred from stage moving. The transient vibration occurred from the stage moving has serious adverse effect to the process because the vibration scale is quite larger than other vibrations. Therefore in this research, a semi-active MR damper, which can control the transient vibration, is adopted. Also the stage needs to be isolated from tiny vibrations from the floor. For this purpose, a dry-frictionless MR damper is required. In order to achieve this goal, a novel type of MR damper is originally designed and manufactured in this work. Subsequently, the damping force characteristics of MR damper are evaluated by simulation and experiment. In addition, the vibration control performance of the MR damper associated with the stage mass is evaluated.

Active Vibration Control of Underwater Hull Structure Using Macro-Fiber Composite Actuators (MFC 작동기를 이용한 수중 Hull 구조물의 능동 진동 제어)

  • Kwon, Oh-Cheol;Sohn, Jung-Woo;Choi, Seung-Bok
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.19 no.2
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    • pp.138-145
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    • 2009
  • Structural vibration and noise are hot issues in underwater vehicles such as submarines for their survivability. Therefore, active vibration and noise control of submarine, which can be modeled as hull structure, have been conducted by the use of piezoelectric materials. Traditional piezoelectric materials are too brittle and not suitable to curved geometry such as hull structures. Therefore, advanced anisotropic piezocomposite actuator named as Macro-Fiber Composite(MFC), which can provide great flexibility, large induced strain and directional actuating force is adopted for this research. In this study, dynamic model of the smart hull structure is established and active vibration control performance of the smart hull structure is evaluated using optimally placed MFC. Actuating performance of MFC is evaluated by finite element analysis and dynamic modeling of the smart hull structure is derived by finite element method considering underwater condition. In order to suppress the vibration of hull structure, Linear Quadratic Gaussian(LQG) algorithm is adopted. After then active vibration control performance of the proposed smart hull structure is evaluated with computer simulation and experimental investigation in underwater. Structural vibration of the hull structure is decreased effectively by applying proper control voltages to the MFC actuators.

The Development of an Automatic Dynamic Inspection System of a Balance Shaft Module (밸런스 샤프트 모듈 자동 동적검사 시스템 개발)

  • Seong, Eun-Je;Kang, Dae-Gyu;Jeong, Chan-Yong;Han, Chang-Soo;Kim, Myung-Soo
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2007.11a
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    • pp.1231-1236
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    • 2007
  • Balance Shaft Module is module parts that is installed to vehicles engine to reduce noise and vibration of vehicles engine. Balance Shaft Module's performance exerts important influence on performance of engine. Therefore, must be able to warrant quality and performance of Balance Shaft Module. Existing product found and revised error at continuous process of production, and estimated failure mode in Balance Shaft Module. Previous method hard to secure product that performance is excellent, and bring a lot of damages economically. Therefore, development of inspectin system for quality inspection of parts and performance test of assembly is essential in Balance Shaft Module. In this study, represented development process of automatic dynamic inspection system to test performance and detect breakdown of Balance Shaft Module that is producing in Dongbo.

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