• Title/Summary/Keyword: natural resonance

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이동질량을 고려한 단순지지된 교량의 진동수 및 공진현상 분석 (The Effect of Moving Mass on Resonance Phenomenon and Natural Frequency of a Simply Supported Beam)

  • 민동주;정명락;박성민;김문영
    • 한국소음진동공학회논문집
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    • 제26권1호
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    • pp.27-38
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    • 2016
  • The purpose of this study is to investigate the influence of moving mass on the vibration characteristics and the dynamic response of the simply supported beam. The three types of the moving mass(moving load, unsprung mass, and sprung mass) are applied to the vehicle-bridge interaction analysis. The numerical analyses are then conducted to evaluate the effect of the mass, spring and damper properties of the moving mass on natural frequencies and dynamic responses of the simply supported beam. Particularly, in the case of the sprung mass, variations of the natural frequency of simply supported beam are explored depending on the position of the moving mass and the frequency ratio of the moving mass and the beam. Finally the parametric studies on the resonance phenomena are performed with changing mass, spring and damper parameters through the dynamic interaction analyses.

2,600 TEU Container Vessel 의 Fresh Water Tank 구조손상 사례 고찰 (Consideration of Structural Damage of Fresh Water Tank for 2,600 TEU Container Vessel)

  • 신성광;안형준;최의걸;고명섭;임효관
    • 대한조선학회 특별논문집
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    • 대한조선학회 2005년도 특별논문집
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    • pp.216-221
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    • 2005
  • Many tanks such as a fresh water tank, an aft peak tank and oil tanks are arranged in the engine room and aft part areas of the ship. By added mass effect of the fluid inside the tanks, the natural frequency will be changed according to filling height of the tank. For this reason, there is possibility of occurrence of excessive vibration by resonance between natural frequencies of local structure and excitation frequencies of the propeller or main engine. Therefore, calculation of natural frequencies is required for structure for many types of tank which are contacting with water or oil to consider added mass effect for anti-resonance design at design stage. In this study, a case of structure damage on the fresh water tank for 2600 TEU container vessel is introduced. In addition, natural frequency analysis and vibration measurement have been performed to investigate vibration characteristics for excessive vibration control.

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Resonance Phenomenon and Its Effects of Laser Texture Disk

  • Choa, Sung-Hoon;Wang, Geng
    • Journal of Mechanical Science and Technology
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    • 제14권7호
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    • pp.744-751
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    • 2000
  • To achieve lower flying height for high areal recording density, the laser zone texturing of the disk needs to be designed to reduce glide height. One problem of the laser bump design is that the regular laser bump pattern often produces glide resonance phenomenon, which leads to failure of the glide height test. However, it was found in this study that glide resonance is an intrinsic problem of the glide head used and resonance phenomenon depends on the type of the head slider, that is, the natural frequency of the slider body. Therefore, higher glide height or glide failure caused by glide resonance does not lead to head/media interface problem in the real drive operating conditions in which the data head is used. Pseudo-random bump pattern greatly reduces the glide resonance. Smaller bump pitch will also help to reduce the glide resonance. However, as bump spacing becomes smaller, glide height will be increased due to increased air pressure developed around the bumps. Lowering bump height is the most effect way to reduce glide avalanche.

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Structure Elucidation for New Sestertepene Alkaloids from the Sponge Sacotragus sp.

  • Rho, Jung-Rae;Shin, Jong-Heon;Lee, Hyi-Seung
    • 한국자기공명학회논문지
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    • 제7권1호
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    • pp.55-61
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    • 2003
  • Sarcotragins C(1) and D(2), two novel compounds, have been isolated from the sponge Sarcotragus sp. collected from Jaeju Island, Korea. The structures of these compounds have been determined to be linear sesterterpene alkaloids on the basis of combined 1D and 2D NMR experiments. The stereochemistry involved was established by comparison of the NMR data with those reported for a similar compound.

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입형펌프의 공진회피와 안전성 평가 (Resonance avoidance and Safety Evaluation of Vertical Pump)

  • 정우영;송진대
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2013년도 춘계학술대회 논문집
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    • pp.698-702
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    • 2013
  • This paper considers the vertical pumps resonance and soundness. Normally large vertical pump's rotating speed is low, so the low natural mode can make a resonance on the motor and motor stand assembly. The pump resonance makes a very high vibration and trouble on the pump systems. Thus to avoid pump resonance when the pump is on the resonance region, we give the added mass method and evaluate the structure soundness by computer simulation and test on the site. Furthermore we evaluate the modal sensitivity and expect running conditions by the using ISO10814.

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홀로그래피 간섭계를 이용한 복합적층판의 결함측정 (Nondestructive Inspection Method of Composite Laminated Plates by Holographic Interferometry)

  • 김석중;김재형;박현철
    • 대한기계학회논문집
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    • 제18권12호
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    • pp.3202-3218
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    • 1994
  • Mode shapes and natural frequencies of vibrating laminated composite plates are taken using real-time and time-average holographic interferometry. Debonds and delamination in the laminated plates are measured nondestructively. During holographic testing of composite plates, it has been found that the conditions for the local resonance in debonds are strongly dependent on the frequency of excitation. A membrane resonance model was proposed to describe this behavior. Relations between characteristic length according to the size, shape of debonds and membrane resonance frequency are presented. Several experiments were performed to verify the membrane resonance model. The agreements between the predicted excitation frequency and the observed resonance frequency are good. The experimental results show that higher stresses and strains due to local resonance lead to the debond detection.

중량바닥충격에 의한 소음 및 진동 특성 (Noise and Vibration Characteristics by Heavy-weight Floor Impact)

  • 서상호;송희수;전진용
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2003년도 추계학술대회논문집
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    • pp.919-922
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    • 2003
  • The correlation between noise and vibration by a heavy-weight floor impact was studied. The triggering technique was used for increasing the reliability and stability to measure the level of sound pressure, sound intensity and vibration acceleration. The simple finite element and rigid body analysis method were suggested to calculate the natural frequencies of the multi-layer floor system. The result show that the isolation material adapted to reduce the light-weight floor impact noise, causing the natural frequency lower, make resonance with dominant driving frequency, and increase the noise level very sharply. Therefore the noise level Peak in the region of low frequency, below 63Hz, would be related with the natural frequencies of the floor system.

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완충재 유무에 따른 표준중량충격원에 의한 콘크리트 바닥 구조의 소음 및 진동 특성 (Noise and Vibration Characteristics of Concrete Floor Structures Using Resilient Materials Driven by Standard Heavy Impact Source)

  • 송희수;전진용;서상호
    • 한국소음진동공학회논문집
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    • 제14권8호
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    • pp.661-667
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    • 2004
  • The characteristics of noise and vibration by a heavy impact source was studied. The triggering method was used for increasing the reliability and stability to measure the level of sound pressure. sound intensity and vibration acceleration. A simple finite element model and a rigid body analysis method were suggested to calculate the natural frequencies of the multi-layer floor system. The results show that the resilient materials decrease the natural frequency of the reinforced concrete slab, make a resonance with dominant driving frequency in the low frequency region, and increase the vibration and noise level. A simple finite element model and rigid body models was suggested to calculate the natural frequencies of the floor systems.

승강기의 종진동에 관한 연구 (A Study on the Longitudinal Vibration of Elevator)

  • 송달호;이유진;최영휴
    • 한국기계연구소 소보
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    • 통권19호
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    • pp.5-14
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    • 1989
  • Analytical and experimental studies are performed to identify the longitudinal vibration characteristics of elevator system such as the natural frequencies, and the magnification factor at resonance. In the analytical study, a computer program is developed to analyze the vibration characteristics of elevator with varing rope length of elevtor, stiffenss of thimble rod spring, and excitation frequency. The shorter rope length and the stiffer thimble rod spring make the natural frequencies of elevator higer. The resonance at the first natural frequency spreads over the entire travelling range, whereas, that at the second one ranges relatively short, region. The first natural frequencies of the Gald-Star Twin Building and the Korea Trading Center Building obtained by the experiment are overall in good agreement with the analysis result..

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액체 화물창내의 SLOSHING 고유주기 산정에 관한 연구 (Estimation of Sloshing Natural Periods in Liquid Cargo Tanks)

  • 신장용;최경식;강신영;김현수
    • 한국해양공학회지
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    • 제8권2호
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    • pp.93-104
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    • 1994
  • Recently in the design of super tankers or LNG carriers which transport a large amount of liquid in the cargo holds, the structural damage due to liquid sloshing becomes an important problem. The impact pressure from sloshing is most violent when the liquid motion of a partially filled tank is in resonance with the motion of a ship. In this paper the sloshing natural periods in liquid cargo tanks are estimated for partially filled tanks with various geometries. Especially the sloshing periods of baffled tanks which are often installed to reduce liquid motion and sloshing forces are calculated. A variational method is adopted to analyze the baffled tank of arbitrary filling depth of liquid. In this approach the liquid domain is divided into several subdomains in which the analytic solutions are potential energy are calculated from the velocity potentials in eachsubdomain. By minimizing the Hamilton's functional, the sloshing natural periods are estimated and the results are compared with experimental and numerical results.

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