• 제목/요약/키워드: mode shape ratio

검색결과 216건 처리시간 0.026초

Fluidelastic Instability Characteristics of Helical Steam Generator Tubes

  • Jo Jong Chull;Jhung Myung Jo;Kim Woong Sik;Choi Young Hwan;Kim Hho Jung
    • Nuclear Engineering and Technology
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    • 제36권4호
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    • pp.364-373
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    • 2004
  • This study investigates the fluidelastic instability characteristics of helical steam generator type tubes used in operating nuclear power plants. To obtain a natural frequency, corresponding mode shape, and participation factor, modal analyses using various conditions are performed for helical type tubes. Investigated are the effects of the number of turns, the number of supports, and the status of the inner fluid on the modal and fluidelastic instability characteristics of the tubes, which are expressed in terms of the natural frequency, the corresponding mode shape, and the stability ratio.

Skeletal Differences in Lower Body and Limbs in Relation to Ecological Traits in Anurans in South Korea

  • Park, Jun-Kyu;Kang, Tae Gyu;Lee, Ji-Eun;Kim, Ji-Eun;Kim, Younghyun;Do, Yuno
    • Proceedings of the National Institute of Ecology of the Republic of Korea
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    • 제3권1호
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    • pp.32-40
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    • 2022
  • The trade-off between morphology and physical function may vary according to ecological traits. Taking a quantitative approach, we attempted to analyze the differences in the skeletal shape of the lower body and limbs in relation to the ecological traits of four anuran species (Dryophytes japonicus, Glandirana rugosa, Pelophylax nigromaculatus, and Lithobates catesbeianus) occurring in South Korea. Body size, locomotor mode, microhabitat, trophic positions, and predator defense mechanisms were selected for the ecological traits of the anurans. The pelvis, ilium, and urostyle, which are associated with locomotor performance, were selected for the skeletal shape of the lower body. The ratio of limbs, which is related to locomotor mode and microhabitat, was confirmed by analyzing the skeletons of the forelimbs (radio-ulnar and humerus) and hindlimbs (femur and tibiofibular). Both landmark-based geometric morphometrics and traditional methods were used for skeletal shape comparison. The skeletal shape of the lower body was completely different among the four species, whereas the ratio of the limbs was only different in D. japonicus. The skeletal shape of the lower body may be related to body mass and predator defense mechanisms, whereas the ratio of the limbs was related to the locomotor mode and microhabitat. Quantifying these morphological differences among various species can help elucidate the mechanisms of behavioral and morphological changes in response to ecological effects.

층강성 손상비를 이용한 전단형 건물의 손상위치 추정에 관한 연구 (Study on The Damage Location Detection of Shear Building Structures Using The Degradation Ratio of Story Stiffness)

  • 유석형
    • 대한건축학회논문집:구조계
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    • 제34권2호
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    • pp.3-10
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    • 2018
  • Damage location and extent of structure could be detected by the inverse analysis on dynamic response properties such as frequencies and mode shapes. In practice the measured difference of natural frequencies represent the stiffness change reliably, however the measured mode shape is insensitive for stiffness change, but provides spatial information of damage. The damage detection index on shear building structures is formulated in this study. The damage detection index could be estimated from mode shape and srory stiffness of undamaged structure and frequency difference between undamaged and damaged structure. For the verification of the observed damage detection method, the numerical analysis of Matlab and MIDAS and shacking table test were performed. In results, the damage index of damaged story was estimated so higher than undamaged stories that indicates the damaged story apparently.

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

  • 황재승;김윤석;주석준
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2002년도 학술대회지
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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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혼합 모드(I/II) 하중에 의한 SA533B 압력용기강의 연성파괴 특성에 관한 연구 (Ductile Fracture Behaviour of SA 533B Pressure Vessel Steel Under Mixed Mode (I/II) Loading)

  • 오동준
    • 대한기계학회논문집A
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    • 제25권11호
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    • pp.1829-1834
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    • 2001
  • The aim of this study is to investigate the ductile fracture behavior under mixed mode (I/II) loading using SA533B pressure vessel steel. Anti-symmetric 4-point (AS4P) bonding tests were performed to obtain the J-R curves under two different mixed mode (I/II) loadings. In addition, the fractographic examination of fracture surfaces was carried out to compare with those of pure Mode I and Mode II. In conclusions, the J-R curves under Mixed Mode (I/II) loading were located between those of Mode I and Mode II loadings. When the mixture ratio of mixed mode (I/II) loading was high, the J-R currie of mixed mode (I/II) loading approached that of pure mode I loading after some amount of crack propagation. In contrast with the above fact, if the mixture ratio was low, the J-R curve looked after that of pure mode II loading. The fractographic evidences such as the shape of dimples under different loading conditions supported these conclusions.

Recent Topics on Injection and Combustion in High Speed Flow (Keynote)

  • Tomioka, Sadatake
    • 한국추진공학회:학술대회논문집
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    • 한국추진공학회 2009년도 제33회 추계학술대회논문집
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    • pp.3-8
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    • 2009
  • Wall flush mounted injector with various orifice shape and injection conditions, were examined to enhance jet penetration and mixing in supersonic cross flow, in view of application to air-breathing accelerator vehicle. Orifice shapes with high aspect ratio were found to preferable for better penetration in the cold flow, and in the reacting flow for scramjet-mode combustion conditions. However, the effectiveness of the high aspect ratio was diminished in the dual-mode combustion conditions. Supersonic injection was applied to the high aspect ratio orifice, and further increase in penetration was observed in the cold and reactive flow for scramjet-mode combustion conditions, however, mixing enhancement due to mixing layer / pseudo-shock wave system interaction was dominant in the dual-mode combustion conditions. Difficulty in attaining ignition in the case with the high aspect ratio orifice was encountered during the combustion tests.

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관막음된 증기발생기 전열관의 유체유발진동 특성 평가 (Estimation of Flow-induced Vibration Characteristics on Plugged Steam Generator Tube)

  • Cho, Bong-Ho;Ryu, Ki-Wahn;Park, Chi-Yong;Park, Su-Ki
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2002년도 추계학술대회논문초록집
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    • pp.390.1-390
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    • 2002
  • In this study, we investigate the plugging effect on the CE type steam generator tube. The natural frequency and mode shape will be changed due to decrease of the effective mass distribution along the tube. We compared the variation of stability ratio for plugged tube with that fur unplugged one. The natural frequency increased because of removing the cooling water inside the steam generator tube, but the stability ratio decreased inversely because of changing the vibrational mode shape. We also investigated the turbulent excitation effect.

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Free vibrations of a two-cable network inter-supported by cross-links extended to ground

  • Zhou, H.J.;Wu, Y.H.;Li, L.X.;Sun, L.M.;Xing, F.
    • Smart Structures and Systems
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    • 제23권6호
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    • pp.653-667
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    • 2019
  • Using cross-ties to connect cables together when forming a cable network is regarded as an efficient method of mitigating cable vibrations. Cross-ties have been extended and fixed on bridge decks or towers in some engineering applications. However, the dynamics of this kind of system need to be further studied, and the effects of extending cross-links to bridge decks/towers on the modal response of the system should be assessed in detail. In this paper, a system of two cables connected by an inter-supported cross-link with another lower cross-link extended to the ground is proposed and analyzed. The characteristic equation of the system is derived, and some limiting solutions in closed form of the system are derived. Roots of cable system with special configurations are also discussed, attention being given to the case when the two cables are identical. A predictable mode behavior was found when the stiffness of inter-connection cross-link and the cross-link extended to the ground were the same. The vector of mode energy distribution and the degree of mode localization index are proposed so as to distinguish global and local modes. The change of mode behaviors is further discussed in the case when the two cables are not identical. Effects of cross-link stiffness, cross-link location, mass-tension ratio, cable length ratio and frequency ratio on $1^{st}$ mode frequency and mode shape are addressed.

자중효과를 고려한 말뚝의 좌굴하중 (Buckling Loads of Piles with Allowance for Self-Weight)

  • 이준규;이광우;전영진;권오일;최용혁;최정식
    • 대한토목학회논문집
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    • 제43권2호
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    • pp.187-193
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    • 2023
  • 이 논문은 말뚝체의 자중을 고려한 말뚝의 좌굴거동에 관한 연구이다. 비균질 지반에 설치된 부분매립 말뚝의 좌굴을 지배하는 미분방정식과 경계조건을 유도하였다. Runge-Kutta법과 Regula-Falsi법을 결합한 수치해석법을 적용하여 말뚝의 좌굴하중과 좌굴형을 산정하였다. 계산된 좌굴하중의 수치해와 문헌값은 잘 일치하였고, 수치예를 통해 말뚝의 자중, 매립비, 세장비, 경계조건 및 지반의 반력형상비, 지반강성비가 말뚝의 좌굴특성에 미치는 영향을 분석하였다. 분석결과, 말뚝의 자중은 말뚝의 좌굴하중을 감소시켰으며 이러한 자중효과의 무시는 부분매립 말뚝의 좌굴하중을 과대평가할 수 있음을 확인하였다.

Vibration and mode shape analysis of sandwich panel with MWCNTs FG-reinforcement core

  • Tahouneh, Vahid
    • Steel and Composite Structures
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    • 제25권3호
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    • pp.347-360
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    • 2017
  • The goal of this study is to fill this apparent gap in the area about vibration analysis of multiwalled carbon nanotubes (MWCNTs) curved panels by providing 3-D vibration analysis results for functionally graded multiwalled carbon nanotubes (FG-MWCNTs) sandwich structure with power-law distribution of nanotube. The effective material properties of the FG-MWCNT structures are estimated using a modified Halpin-Tsai equation. Modified Halpin-Tsai equation was used to evaluate the Young's modulus of MWCNT/epoxy composite samples by the incorporation of an orientation as well as an exponential shape factor in the equation. The exponential shape factor modifies the Halpin-Tsai equation from expressing a straight line to a nonlinear one in the MWCNTs wt% range considered. Also, the mass density and Poisson's ratio of the MWCNT/phenolic composite are considered based on the rule of mixtures. Parametric studies are carried out to highlight the influence of MWCNT volume fraction in the thickness, different types of CNT distribution, boundary conditions and geometrical parameters on vibrational behavior of FG-MWCNT thick curved panels. Because of using two-dimensional generalized differential quadrature method, the present approach makes possible vibration analysis of cylindrical panels with two opposite axial edges simply supported and arbitrary boundary conditions including Free, Simply supported and Clamped at the curved edges. For an overall comprehension on 3-D vibration analysis of sandwich panel, some mode shape contour plots are reported in this research work.