• Title/Summary/Keyword: Vibration isolation

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Vibration characteristic of rubber isolation plate-shell integrated concrete liquid-storage structure

  • Cheng, Xuansheng;Qi, Lei;Zhang, Shanglong;Mu, Yiting;Xia, Lingyu
    • Structural Engineering and Mechanics
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    • v.81 no.6
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    • pp.691-703
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    • 2022
  • To obtain the seismic response of lead-cored rubber, shape memory alloy (SMA)-rubber isolation Plate-shell Integrated Concrete Liquid-Storage Structure (PSICLSS), based on a PSICLSS in a water treatment plant, built a scale experimental model, and a shaking table test was conducted. Discussed the seismic responses of rubber isolation, SMA-rubber isolation PSICLSS. Combined with numerical model analysis, the vibration characteristics of rubber isolation PSICLSS are studied. The results showed that the acceleration, liquid sloshing height, hydrodynamic pressure of rubber and SMA-rubber isolation PSICLSS are amplified when the frequency of seismic excitation is close to the main frequency of the isolation PSICLSS. The earthquake causes a significant leakage of liquid, at the same time, the external liquid sloshing height is significantly higher than internal liquid sloshing height. Numerical analysis showed that the low-frequency acceleration excitation causes a more significant dynamic response of PSICLSS. The sinusoidal excitation with first-order sloshing frequency of internal liquid causes a more significant sloshing height of the internal liquid, but has little effect on the structural principal stresses. The sinusoidal excitation with first-order sloshing frequency of external liquid causes the most enormous structural principal stress, and a more significant external liquid sloshing height. In particular, the principal stress of PSICLSSS with long isolation period will be significantly enlarged. Therefore, the stiffness of the isolation layer should be properly adjusted in the design of rubber and SMA-rubber isolation PSICLSS.

Equivalent Stiffness Modeling of Isolators to Consider Wave Effects in Multi-dimensional Vibration Isolation Analysis, via Vibrational Power (진동파워를 이용한 다차원 진동절연계 해석시 절연요소의 파동효과를 고려한 등가강성화)

  • 최규상;이호정;김광준
    • Journal of KSNVE
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    • v.9 no.3
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    • pp.517-524
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    • 1999
  • Mathematical formulas for multi-dimensional isolation analysis via vibrational power transmission can be derived in a rather simple form when the wave effects of the isolators are completely neglected. With increase of frequency range of interest, however, the wave effects play a very important role and hence cannot be neglected. The formulas get involved accordingly. In this study, a method of equivalent stiffness modeling of the isolators to include the wave effects is proposed in such a way that not only the complexity of the mathematical expressions but also that of experiments of necessity can be reduced. This method is illustratively applied to a two-dimensional vibration isolation system with nonrigid source and base structures.

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Evaluation method of isolation performance for MIMO isolation table using singular value of transmissibility matrix (전달율 행렬의 특이치를 이용한 다입력/다출력 제진대계의 절연성능 평가법)

  • Sun, Jong-Oh;Kim, Kwang-Joon
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2012.04a
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    • pp.324-329
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    • 2012
  • Isolation tables are widely used for precision equipments and their isolation performances have been usually expressed and evaluated by transsmissibility. However, transmissibility is a concept for 1-degree of freedom(DOF) system. In practice, isolation tables are supproted by more than 4 springs. Each spring is subjected to vertical and horizontal ground vibrations, and also the table has more than 1-DOF. Therefore, isolation tables should be treated as multi-input/multi-output(MIMO) system of which isolation performance is expressed by transmissibility matrix. However, the matrix is too complicated to be an index for a system. In this paper, maximum singular value of transmissibility matrx is suggested as a simple performance index of a MIMO isolation system. Physical meaning of singular value is explained using a simple a 2-DOF isolation table. Furthermore, maximum singular values of passive, 3-DOF active and 6-DOF active isolation tables are obtained through experiments, and their meaning are explained and compared with each other.

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Vibration Transmissibility Analysis and Measurement of Automotive Clutch Spring Dampers (차량 클러치 스프링 댐퍼의 진동 전달률 해석 및 측정)

  • Jang, Jae-Duk;Kim, Gi-Woo;Kim, Won-Jin
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.23 no.10
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    • pp.902-908
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    • 2013
  • The input torque ripple induced by combustion engines is a significant source of NVH(noise, vibration and harshness) problem in automotive transmissions. Because this torque fluctuation is primarily transmitted to the input shaft of automotive powertrains(e.g., automatic transmissions) when the lock-up clutches are closed, a torsional damper with helical springs is generally inserted between engine and transmissions to isolate the input vibratory energy, which is essential for the passenger comfort. The torsional vibration isolator exhibits frequency ranges in which there is low vibration transmissibility. However, the isolation performance is currently evaluated through the static torsional spring characteristics. In this study, the transmissibility of torsional spring dampers, essential dynamic performance index for vibration isolator, is first experimentally evaluated.

Development and Application of Educational Equipment for Vibration Engineering (진동공학 교육장비 개발 및 적용)

  • Rim, Kyung-Hwa;Yang, Xun
    • The Journal of Korean Institute for Practical Engineering Education
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    • v.1 no.1
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    • pp.61-65
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    • 2009
  • Due to the less variety of experiment equipments for engineering education, the development of designated educational equipment is really in urgent need at most time. Especially for the in-depth engineering major subject, vibration engineering, there are almost no related educational equipments in Korea. Accordingly, in order to simulate the vibration phenomena occurred in the actual field, the development of educational equipment for vibration engineering theory and experiment education is required. This paper introduces four development educational equipments developed in graduated research works, which are critical speed test educational equipment, balancing machine educational equipment, isolation educational equipment using eddy current and active vibration isolation educational equipment. Through using them in experiment lesson, the utilization and practicality of educational equipment are verified. The proposed improvement for future development and application of educational equipment is shown in addition.

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Concept Design of Vibration Isolation System for Development of Optical Payload of Satellite (위성광학탑재체 개발을 위한 나노급 방진장치 개념 설계)

  • Lee, Sang-Hoon;Cho, Hyok-Jin;Seo, Hee-Jun;Kim, Young-Key;Moon, Guee-Won;Moon, Sang-Moo;Kim, Hong-Bea
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2005.05a
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    • pp.949-952
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    • 2005
  • According to the national space program in Korea, is satellites will be launch into space up to 2015. Especially, KARI is going to develope of its own a high resolution camera of less than 1m to be mounted on next Multipurpose Satellite. When performing testing of large spacecraft or hardware that will be launched into orbit, it is necessary to conduct a testing with space-simulated environment. To achieve this requirement, thermal vacuum chamber is generally used. KARI has been developed a very Large Thermal Vacuum Chamber(LTVC) from 2003 to accomodate future space program, such as KOMPSAT, COMS, and Launch vehicles. This new facility will be used to qualify the first self developed High Resolution Camera, which will be loaded on KOMPSAT-3. To perform an optical test for space camera, it is necessary to provide vibration free environment. Thus the vibration responses on the optical table due to external vibration should be minimized by using a special isolation system. In this paper, we propose the concept design of vibration isolation system for the development of the high resolution camera.

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A Study on the Property of the Floor Impact Isolation Material in Apartment House (공동주택 바닥충격음 완충재료의 물성 권장안)

  • 정갑철;양관섭
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2001.05a
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    • pp.59-64
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    • 2001
  • Recently, among those general contractors and construction material production companies in korea, this concept is lively obtained to reduce the floor impact sound. This attempt is continuously tried for developing the floor impact isolation material. However the assesment of the isolation performance is often ignored and even there seems no differences in comparison with the general the isolation performance of the floor impact. This is often occurred for their only respect with the material of the floor impact isolation performance. Therefore, this study analysed the expected problems for site application of currently applied the isolation material and its capacity which as the floor impact reducing material, and presented several major assesment items and checklist which should be inspected in advance of their development or site application.

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Evaluation of high performance isolation spring mount by attached masses (부가질량 효과에 따른 고효율 방진마운트의 진동저감 성능평가)

  • Ho, Kyoung-Chan;Lee, Byoung-Chul;Lee, Yong-Hyun;Lee, Young-Je;Kim, Min-Bae
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2007.11a
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    • pp.1247-1252
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    • 2007
  • The machine equipment of the building inside occurs the vibration. In order to reduce this vibration spring, rubber pad is used. But efficiency of this classical mount is restricted at specific frequency. Also maximum efficiency design is complicated. This paper proposes and examines a attached mass isolation system that is used to reduce transmitted vibrations from machines onto their floor support. With attached mass the low frequency performance is improved overall. The performance is showed in 2 degree of freedom model test. And the proposed isolator has been validated by dynamic test and good agreement between theoretical and experimental results has been obtained.

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The Study of Dynamic Characteristic of a Viscous Fluid Damper in Vibration Isolation (진동 방지용 점성 유체 댐퍼의 동특성 해석에 관한 연구)

  • 권오병;이강민;김유민;고철수
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2001.05a
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    • pp.1136-1140
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    • 2001
  • Viscous fluid damper is used for vibration isolation of piping system, presses, turbo-generator and other heavy industrial equipments, as well as seismic isolation of buildings structure. So dynamic characteristic of viscous fluid damper is very important. This paper presents the result of the study of dynamic characteristic of viscous fluid damper. And the force-displacement relation of the viscous damper is described by experimentally calibrated fractional derivative Maxwell Model. The proposed model is validated by dynamic testing and A good agreement between predicted and experimental results is obtained.

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Examination on Shock Vibration of Feed-Water Recirculation piping in Power Site (발전소 대형 수배관계의 충격성 이상 과도진동의 특성 고찰 사례)

  • Kim, Yeon-Whan;Yang, Gyeong-Hyeon;Bae, Si-Yeon;Yu, Jae-Myeong;Jo, Jong-Hyeon
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2011.10a
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    • pp.475-479
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    • 2011
  • Leak problem with large pressure drop occurrs non-periodic shock pulsation due to the deterioration of a isolation valve in feed-water recirculation piping system. This paper discusses on the shock vibration and noise occurred due to the effect of acoustical shock pulsations by degradation of the isolation valve in a power site.

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