• Title/Summary/Keyword: Impact Vibration

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Estimation of Ground Vibrations Around a Pillar Due to Blast Loading and the Impact of Flyrocks (발파하중 및 비석의 충격에 의한 광주의 지반진동의 예측 연구)

  • Lee, Sang-Gon;Kang, Choo-Won;Chang, Ho-Min;Ryu, Pog-Hyun;Kim, Jang-Won;Song, Ha-Rim;Kim, Seung-Eun
    • Explosives and Blasting
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    • v.28 no.1
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    • pp.1-10
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    • 2010
  • In blasting for lighting, fatigue behaviors of pillars such as destruction and deformation may occur due to blasting vibration and flyrock, which may cause collapses of cavities. This study aims to identify dynamic behavior of pillars to maintain efficient safety of cavities in large drafts. when they collide with flyrocks under blasting for the excavation. For the purpose, we compared ground vibration around pillar when flyrock collided with the pillar and that when explosive blast happened for the excavation. we conducted fragmentation analysis of the flyrock and compared impact vibration obtained from empirical equation with ground vibration obtained from regression analysis of real vibration data. also we compared those with results analyzed from numerical analysis.

Dynamic Characteristic Analysis of MR Impact Damper for Vehicle System (차량용 MR충격댐퍼의 동특성 해석)

  • Song, Hyun-Jeong;Woo, Da-Vid;Choi, Seung-Bok
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.16 no.7 s.112
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    • pp.754-761
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    • 2006
  • This paper presents the dynamic characteristics of MR impact damper for vehicle collision system. Various types of mechanism have been proposed to reduce force transmitted to the vehicle chassis and finally to protect occupants from injury. In the case of head-on collision, the bumper makes main role of isolation material for collision attenuation. In this study, the proposed bumper system consists of MR impact damper and structures. The MR impact damper utilizes MR fluid which has reversible properties with applied magnetic field. The MR fluid operates under flow mode. The bellows is used for generation of fluid flow. A mathematical model of the MR impact damper is derived incorporating with Bingham model of the MR fluid. Field dependent damping force is investigated with time and frequency domain. The MR impact damper is then incorporated with vehicle crash system. The governing equation of motion of vehicle model is formulated considering occupant model. Dynamic characteristics of vehicle collision system investigated with computer simulation.

The Effect of Aerated Concrete containing Foam Glass Aggregate on the Floor Impact Sound Insulation (발포유리 혼합기포 콘크리트의 바닥충격음 차단성능 영향에 관한 연구)

  • Yun, Chang-Yeon;Jeong, Jeong-Ho;Kim, Myung-Jun
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.23 no.5
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    • pp.414-422
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    • 2013
  • As structure-borne sound, the floor impact sound is one of the serious noises in residential building. Most of heating system applied to the typical Korean residential building is floor heating system which is called ondol. The ondol usually consists of finishing material, mortar with heating coil, light-weight aerated concrete and reinforced concrete. This study focused on the isolation of heavy-weight impact sound and modification of mortar and light-weight aerated concrete. Specifically the glass foam aggregate was added on light-weight aerated concrete. Also, water-cement ratio and amount of cement on mortar were revised. The sound pressure level of heavy-weight impact was measured in reverberation chamber using both bang-machine and impact ball. The size of specimen was 1 m by 1 m. Substitution ratio of glass foam aggregate on light-weight aerated concrete shows relationship with heavy-weight impact sound pressure level. In addition, heavy-weight impact sound pressure level was decreased with increment of water-cement ratio and amount of cement on mortar.

Dynamic Characteristic Analysis of MR Impact Damper for Vehicle System (차량용 MR 충격댐퍼의 동특성 해석)

  • Song, Hyun-Jeong;Woo, David;Choi, Seung-Bok
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2006.05a
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    • pp.147-152
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    • 2006
  • This paper presents the dynamic characteristics of MR impact damper for vehicle collision system. Various types of mechanism have been proposed for reduce transmitted force to vehicle chassis and finally protect occupants from injury. In the case of frontal collision, the bumper make main role of isolation material for collision attenuation. In this study, proposed bumper system composed of MR impact damper and structures. The MR impact damper is to adopted MR fluid which has reversible properties with applied magnetic field. MR fluid operates under flow mode with Bingham flow and bellows is used for generation of fluid flow. Mathematical model of MR impact damper incorporated with MR fluid is established. Field dependent damping force is investigated with time and frequency domain. The MR impact damper is then incorporated with vehicle crash system. The governing equation of motion of vehicle model is formulated considering occupant model. Dynamic characteristics of vehicle collision system investigated with computer simulation.

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Piezoelectric Vibration Energy Harvester Using Indirect Impact (간접 충격을 이용한 압전 방식 진동형 에너지 하베스터)

  • Ju, Suna;Ji, Chang-Hyeon
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.66 no.10
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    • pp.1499-1507
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    • 2017
  • This paper presents an impact-based piezoelectric vibration energy harvester using a freely movable metal sphere and a piezoceramic fiber-based MFC (Macro Fiber Composite) as piezoelectric cantilever. The free motion of the metal sphere, which impacts both ends of the cavity in an aluminum housing, generates power across a cantilever-type MFC beam in response to low frequency vibration such as human-body-induced motion. Impacting force of the spherical proof mass is transformed into the vibration of the piezoelectric cantilever indirectly via the aluminum housing. A proof-of-concept energy harvesting device has been fabricated and tested. Effect of the indirect impact-based system has been tested and compared with the direct impact-based counterpart. Maximum peak-to-peak open circuit voltage of 39.8V and average power of $598.9{\mu}W$ have been obtained at 3g acceleration at 18Hz. Long-term reliability of the fabricated device has been verified by cyclic testing. For the improvement of output performance and reliability, various devices have been tested and compared. Using device fabricated with anodized aluminum housing, maximum peak-to-peak open-circuit voltage of 34.4V and average power of $372.8{\mu}W$ have been obtained at 3g excitation at 20Hz. In terms of reliability, housing with 0.5mm-thick steel plate and anodized aluminum gave improved results with reduced power reduction during initial phase of the cyclic testing.

Experimental Study on the Evaluation of Behavior for Floating Track System Using a Resilient Rubber Mat (고무방진매트가 적용된 플로팅궤도시스템의 거동분석을 위한 실험적 연구)

  • Lee, Siyong;Jeong, Incheol;Choi, Jungyoul;Park, Yonggul
    • Journal of the Korean Society for Railway
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    • v.17 no.4
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    • pp.281-288
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    • 2014
  • The objective of this study was to estimate the vibration reduction capacities of a floating track system using a resilient rubber mat, and to compare the results with the track support stiffness and track impact factor of a conventional slab track system by performing field tests using actual vehicles running along a service line. The theoretically designed track support stiffness and track impact factor were compared with the measured track support stiffness and track impact factor for each tested track. The calculated and measured track support stiffness of the floating track system were found to be similar, and the floating track system satisfied the design specifications of the track impact factor. The overall vibration level and track support stiffness of the floating track system were thereupon found to be significantly lower than those of the conventional slab track system. The experimental results thus showed that the vibration reduction effect of the floating track system is greater than that of the conventional slab track.

A Study on the Clutch Damper Design Technique (클러치 댐퍼 설계 기법 연구)

  • 안병민;장일도;최은오;홍동표;정태진
    • Journal of KSNVE
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    • v.7 no.6
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    • pp.1031-1037
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    • 1997
  • The main torsional vibration source of the driveline is the fluctuation of the engine torque. The gear rattle is generated by an impact in the backlash due to this torsional vibration. Optimization of the clutch torsional characteristic is one of the effective methods to reduce the idle gear rattle. Many researches have been reported on this problem but only few of them give sufficient consideration to the detail clutch modeling and clutch design parameters (stiffness, hysteresis torque, preload, first stage length). This paper pays attention to the gear impact mechanism and clutch design parameters to reduce the idle gear rattle with computer simulation.

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Measurements of the vibration responses of CLD structures varied in thickness of the damping layer (제진층의 두께변화에 따른 CLD 구조의 진동응답 측정)

  • Lee, Sin-Young;Yoo, Seung-Yup;Jeon, Jin-Yong;Kim, Seung-Joon;Park, Jun-Hong
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2007.11a
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    • pp.1463-1466
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    • 2007
  • Visco-elastic damping material for reducing heavy-weight floor impact noise and vibration in reinforced concrete structures was tested according to its thickness in the damping layer. The effect of damping material was compared with 20, 15, 10 and 5mm thickness. The wave propagation characteristics was measured for suggestion of an efficient method to reduce the floor impact noise. The method was proposed using the flexural wave propagation characteristics. The result showed that reduction of the thickness of damping layer made a slight difference; the natural frequency moved to higher frequency and the amplitude increased at low frequencies with 5mm thickness of damping material.

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Measurement of Dynamic Properties of Concrete Structures Using Beam Transfer Function Methods (보 전달함수법을 이용한 콘크리트 구조물의 동특성 측정)

  • Kim, Seung-Joon;Yoo, Seung-Yup;Jeong, Yeong;Jun, Jin-Yong;Park, Jun-Hong
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2006.11a
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    • pp.950-953
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    • 2006
  • The floor impact noise of concrete structures in apartments buildings is affected from the flexural wave propagation characteristics. Accordingly, the measurement of wave propagation characteristics is required for suggestion of efficient method to reduce the impact noise. The purpose of this article is to propose an experimental technique to measure dynamic properties of concrete structures. The method was proposed using the flexural wave propagation characteristics. Wave speeds, bending stiffness and their loss factors are estimated from which the vibration dissipation capabilities are investigated. Several different concrete beam structures were custom-built for measurement. The damping treatments using viscoelastic materials for reducing noise generation are also tested. The beam transfer function of the damped beam is predicted using the compressional damping model from which the mechanism of the vibration energy dissipation is investigated.

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Characteristics of Construction Machinery Noise and Vibration (건설기계류 소음·진동 특성)

  • Kang, Daejoon;Lee, W.S.;Lee, J.W.;Hong, J.K.
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.15 no.6 s.99
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    • pp.645-651
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    • 2005
  • The construction noise Is one of the main causes of environmental impact. The complaints about it have been increasing every year. In order to reduce construction machinery noise, the product noise labeling for construction machinery has been recommended since 1 February 1996 and In the near future the government will convert the recommended product noise labeling to the mandatory product noise labeling for high noise construction machinery. Therefore, we investigated the noise and vibration level of 302 construction machines in construction work sites. This paper presents the basic data that will be used for setting the standard of construction machinery noise and predicting the noise level near construction work sites in environmental Impact assessment.