• Title/Summary/Keyword: structural vibration

Search Result 4,086, Processing Time 0.027 seconds

Development of Active Control System for Structural Vibration Using a Hydraulic Actuator (유압식 Actuator를 이용한 구조물 진동의 능동제어시스템 개발)

  • S.J. Moon;T.Y. Chung
    • Journal of the Society of Naval Architects of Korea
    • /
    • v.32 no.1
    • /
    • pp.94-102
    • /
    • 1995
  • The active control system of structural vibration using a hydraulic actuator is developed. The developed system consists of three parts : a hydraulic unit, an actuator unit and a control unit. Structural vibration is sensored by the accelerometer attached to the structure and reduced by the optimally controlled motion of active mass giving anti-phase inertia force to the structure. It is experimentally confirmed that the vibration level of model structure is reduced to about 1/6 by the developed active control system.

  • PDF

A Study on the Vibratory Characteristics of the Stack in Fuel Cell Vehicle at Driving Condition (연료전지 차량 주행시 스택의 진동 특성 연구)

  • Ju, Hyung-Jun;Kim, Gi-Hoon;Park, Jae-Yong
    • Transactions of the Korean Society of Automotive Engineers
    • /
    • v.18 no.5
    • /
    • pp.50-55
    • /
    • 2010
  • In recent years, the development of fuel cell vehicles has further accelerated because of environmental problem and petroleum resources shortage. The fuel cell vehicles have the stack which converts fuel to electricity. The stack is usually mounted by bush to isolate the vibration of chassis and body. This paper analyzed the vibratory characteristics of stack and chassis, body system. The wheel forces of fuel cell vehicle are measured to estimate the road load data. And the paths of vibration from wheel to stack are analyzed by CAE. According to the test and CAE results, the improvement of stack vibration are evaluated.

Comparison of the Natural Period Obtained by Eigenvalue Analysis and Ambient Vibration Measurement in Bearing-Wall Type Apartment (고유치해석과 진동계측을 통한 벽식 공동주택의 고유주기 비교)

  • Yoon, Sung-Won;Jeong, Sug-Chang;Lim, In-Sik
    • Journal of Korean Association for Spatial Structures
    • /
    • v.6 no.3 s.21
    • /
    • pp.43-50
    • /
    • 2006
  • This paper is concerned with the natural periods of ambient vibration and eigenvalue analysis. Ambient vibration tests were conducted to four bearing-wall reinforced concrete buildings ranging from twelve to nineteen stories. The performance of modeling in eigenvalue analysis was investigated using consideration of rigidity out of the plane in the slab and the non-structural bearing wall. Measured natural period was also compared with the value by the KBC2005. Natural period of the short direction in eigenvalue analysis is well fitted with the measured one. In the other hand, Natural period of the long direction in eigenvalue analysis is slightly more overestimated than the measured one. Natural period of the long direction in eigenvalue analysis was found to be enhanced by considering the effect of the stiffness out of the plane of the slab and non-structural wall in the structural modeling.

  • PDF

Development of a Wireless Vibration Monitoring System for Structural Health Evaluation (구조안전성 평가를 위한 무선 진동 모니터링 시스템 개발)

  • Shim, Bo-Gun;Lee, Shi-Bok;Chae, Min-Sung
    • Transactions of the Korean Society for Noise and Vibration Engineering
    • /
    • v.20 no.2
    • /
    • pp.166-171
    • /
    • 2010
  • Wired monitoring systems have been used for damage detection and dynamic analysis of large structures(bridges, dams, plants, etc.). However, the real-world applications still remain limited, mainly due to time and cost issues inherent to wired systems. In recent years, an increasing number of researchers have adopted WSN(wireless sensor network) technologies to the field of SHM(structural health monitoring). Accurate time synchronization is most critical for the wireless approach to be feasible for SHM purpose, along with sufficient wireless bandwidth and highly precise measuring resolution. To satisfy technical criteria stated above, a wireless vibration monitoring system that uses high-precision MEMS(micro-electro-mechanical system) sensors and A/D convertor is discussed in detail. It was found experimentally that the level of time synchronization fell within $200\;{\mu}sec$.

A Study on Noise Reduction of a HDD by Structural moification of Cover (Cover의 구조변겨을 통한 HDD의 소음 저감에 관한 연구)

  • 이성진;유성우;홍순교;이장무
    • Journal of KSNVE
    • /
    • v.10 no.5
    • /
    • pp.859-864
    • /
    • 2000
  • An effective and new method of reducing the noise of a HDD by structural modification of cover was investigated in this study. The correlation between the noise characteristics of the HDD and the vibration characteristics of the cover, which is the main source of the HDD noise, is found from experiments. A theoretical analysis is performed to find the modification method of the cover, and this modification method is applied the real cover of the HDD. The modification reduces the vibration of the cover transferred from driving motor. The effect of the modification is verified through noise tests.

  • PDF

Experimental investigation of an active mass damper system with time delay control algorithm

  • Jang, Dong-Doo;Park, Jeongsu;Jung, Hyung-Jo
    • Smart Structures and Systems
    • /
    • v.15 no.3
    • /
    • pp.863-879
    • /
    • 2015
  • This paper experimentally investigates the effectiveness and applicability of the time delay control (TDC) algorithm, which is simple and robust to unknown system dynamics and disturbance, for an active mass damper (AMD) system to mitigate the excessive vibration of a building structure. To this end, the theoretical background including the mathematical formulation of the control system is first described; and then, a thorough experimental study using a shaking table system with a small-scale three-story building structural model is conducted. In the experimental tests, the performance of the proposed control system is examined by comparing its structural responses with those of the uncontrolled system in the free vibration and forced vibration cases. It is clearly verified from the test results that the TDC algorithm embedded AMD system can effectively reduce the structural response of the building structure.

Seismic and vibration mitigation for the A-type offshore template platform system

  • Lee, Hsien Hua
    • Structural Engineering and Mechanics
    • /
    • v.6 no.3
    • /
    • pp.347-362
    • /
    • 1998
  • In this study an improved design method for the traditional A-type(or V-type) offshore template platform system was proposed to mitigate the vibration induced by the marine environmental loadings and the strong ground motions of earthquakes. A newly developed material model was combined into the structural system and then a nonlinear dynamic analysis in the time domain was carried out. The analysis was focused on the displacement and rotation induced by the input wave forces and ground motions, and the mitigation effect for these responses was evaluated when the viscoelastic damping devices were applied. The wave forces exerted on the offshore structures are based on Stokes fifth-order wave theory and Morison equation for small body. A step by step integration method was modified and used in the nonlinear analysis. It was found that the new design approach enhanced with viscoelastic dampers was efficient on the vibration mitigation for the structural system subjected to both the wave motion and the strong ground motion.

Micro-vibration Control in Concrete Slabs (콘크리트 슬래브의 미진동 제어)

  • 노병철;변근주;양재성
    • Journal of the Earthquake Engineering Society of Korea
    • /
    • v.2 no.4
    • /
    • pp.63-72
    • /
    • 1998
  • This study is to develop a technique for micro-vibration analysis and control of concrete slabs to fulfil the vibration criteria for working environments. The proposed technique is for determining the unknown forces from accelerance of two concerned points and the micro-vibration analysis and control of concrete slabs are then validated by numerical model and structural tests. And it is recommended that the natural frequency of structures for micro-vibration control design should be above 25 Hz~30 Hz, and 1.5 times forcing frequency in case of 3~5% structural damping ratio of concrete structures.

  • PDF

Study on the Noise Reduction in the Rotary Compressor Using BLDC Motor (BLDC 모터를 적용한 로터리 컴프레서 소음 저감에 관한 연구)

  • Kim, Jin-Soo;Lim, Kyung-Nae;Ku, Se-Jin;Lee, Jang-Woo;Jeon, Si-Moon
    • Transactions of the Korean Society for Noise and Vibration Engineering
    • /
    • v.18 no.9
    • /
    • pp.920-929
    • /
    • 2008
  • The main noise and vibration source of the BLDC rotary compressor for air conditioner was analyzed by using the measurement of noise and vibration, noise contour, and experimental modal analysis. The source is presumed to the mechanical resonance excited by the electromagnetic attractive force of the BLDC motor. To reduce the excessive noise of the BLDC rotary compressor due to the mechanical resonance, air-gap enlargement and structural dynamic modification were applied in this paper. Its validations were conducted by the analysis of the electromagnetic attractive force which is generated by the BLDC motor and by the measurement of noise and vibration of the BLDC rotary compressor. By enlarging the length of air-gap and conducting the structural dynamic modification, the noise and vibration in the compressor was significantly improved by 4.5 dB(A) and 56 percent, respectively.

Acoustic Loads Test of the Upper Stage of KSLV-I (소형위성발사체 상단부의 음향하중시험)

  • Chun, Young-Doo;Park, Jong-Chan;Chung, Eui-Seung;Park, Jung-Joo;Cho, Kwang-Rae
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 2007.05a
    • /
    • pp.224-227
    • /
    • 2007
  • This paper introduces the results of acoustic loads test conducted on the upper stage assembly of KSLV-I, which is the first Korea space launch vehicle. A launch vehicle and its payloads are subjected to severe acoustic pressure loading when they lift off and ascent during the transonic periods. Acoustic loadings are spreaded out broad frequncy-spectrum up to 10,000Hz. Acoustic loads are a primary source of structural random vibration of the upper stage and payloads. Therefore, in order to verify the structural integrity of the upper stage assembly of KSLV-I and the survivability of its components under severe random vibration environment, acoustic loads test is conducted in the high intensity acoustic chamber with 142dB (overall SPL). The results show the structural design and component random vibration specifications well meet with the environmental requirements.

  • PDF