• Title/Summary/Keyword: Campbell Diagram

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Stress and Modal Analysis for the Rotor System of a Medical Centrifuge using Finite Element Method (유한요소법을 이용한 의료용 원심분리기 로터의 응력 및 고유치 해석)

  • Kim, Sung-Min;Yang, In-Chul;Kim, Do-Gyoon;Kim, Hak-Chul
    • Journal of the Korean Society for Precision Engineering
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    • v.24 no.6
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    • pp.78-85
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    • 2007
  • In this study, we performed finite element analysis for the design of a medical centrifuge and two-types of centrifuge were compared with each other. The types of centrifuge are 2-arm straight type and 3-arm type. Structural analysis was done with respect to the change of the rotational speed of the rotor of a centrifuge. When the rotor of centrifuge was rotated, the von Mises stress of 2-arm straight type-rotor was compared with the von Mises stress of 3-arm type. The margin of safety was estimated from the result. We found the critical speed of centrifuge from the campbell diagram by modal analysis.

A Study on Hovering Performance of Personal Air Vehicle According to Distance between Rotor Blade Axis via Computational Fluid Dynamics (전산유체역학을 통한 PAV의 로터 블레이드 축간거리에 따른 호버링 성능 변화 연구)

  • Yoon, Jaehyun;Noh, Wooseung;Doh, Jaehyeok
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.21 no.5
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    • pp.53-60
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    • 2022
  • In this study, the conceptual design and performance evaluation of a personal air vehicle (PAV) is presented, which is a potential futuristic individual transportation. The blade element theory (BET) is employed to compute a rotational velocity. A computational fluid dynamics (CFD) simulation is performed to investigate the difference in the thrust performance in the rotor axis distance of a quad-copter PAV in hovering. Modal analysis is performed to create a Campbell diagram to investigate critical speed. Consequently, a quad-copter PAV changes the aerodynamics thrust and critical velocity according to the rotor axis distance.

A Study on Shaft Dynamic Characteristic for G/T 250TON Double-Ended Car-Ferry (G/T 250톤 양방향 차도선 축계의 동특성에 관한 고찰)

  • Kang, Byoung-Mo;Oh, Young-Cheol;Bae, Dong-Gyun;Seo, Kwang-Cheol;Ko, Jae-Yong
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.21 no.1
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    • pp.83-90
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    • 2015
  • The car ferry operating between the mainland and the island plays an important role on transportation of goods and passengers. Therefore, the improvement of efficiency and safety as well as economic factor are importantly considered in the development process of car ferry. Double-ended car ferry is already popularized because of its economic feasibility and convenience for passenger in Europe and developed countries, and the demand is booming in domestic. In this paper, dynamic characteristics of propeller shaft and strength in double-ended car ferry are analyzed using campbell diagram and modal analysis. Based on the analysis of dynamic characteristics, resonant phenomenon and critical speed are stable when occurring the propeller shaft vibration due to forward and reverse propeller shaft working.

A Mode Sorting Method Using the MAC of a Rotor-bearing System (MAC을 이용한 회전축계 시스템의 모드정렬 방법)

  • Lim, Jonghyuk;Kim, Minsung;Lee, Kyuho;Park, Chuljun;Chung, Jintai
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.25 no.5
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    • pp.329-336
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    • 2015
  • This paper presents a sorting method of mode vectors and natural frequencies about a rotor-journal bearing system. The rotor is solved by the finite element method, the bearing stiffness and damping coefficient are solved by the finite difference method. At any rotation speed section through the eigenvalue analysis of the system, mode vectors and natural frequencies not sorted are confirmed via the Campbell diagram and the MAC(modal assurance criterion). To sort mode vectors and natural frequencies of the section, a mode sorting method is presented through a method of rearranging the MAC of the mode vectors. Finally, the mode vectors and the natural frequencies are sorted by using the presented method, these are verified through the MAC.

Evaluation of Blades Vibration Reliabilities of KGT-74 Small Gas Turbine (KGT-74소형 가스터빈 블레이드의 진동 신뢰성 평가)

  • 김영철;이동환;이안성
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.14 no.5
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    • pp.410-415
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    • 2004
  • To ensure a safe operation of the prototype KGT-74 kW small gas turbine, vibrational reliabilities of the compressor 1st, 2nd, and 3rd stages and turbine blades have been estimated and reviewed. FE analyses have been carried out to obtain the natural vibration characteristics of the blades, and impact modal testings have been performed on every each one of the blades to measure their 1st natural frequencies. Then, the Campbell diagram analyses have been carried out to judge the safety of the blades from resonant failures up to 6k harmonics. Results show that the compressor 1st stage blade is exposed to a potential resonant failure with 3k harmonic around a rated speed of 30,000 rpm but that the other compressor 2nd and 3rd stages and turbine blades are safe from resonant failures. Finally, 27,900 rpm is selected as the safe operation limit for the KGT-74 ㎾ gas turbine relative to the blade vibrations.

Structural Characteristics for the Hybrid Street-Lamp of a Small Wind Turbine and Photovoltaic Power System (풍력-태양광 복합 가로등 구조특성 연구)

  • Jeon, Hyun-Jun;Jang, Choon-Man
    • Journal of Hydrogen and New Energy
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    • v.24 no.6
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    • pp.566-572
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    • 2013
  • In the present study, structure analysis has been performed to understand the deflection and stress distribution for a hybrid street-lamp having a vertical-axis wind turbine and a photovoltaic panel. Modal analysis is also evaluated to avoid resonance gerenerated by sychronism between a turbine and a lamppost. To analyze deflection, stress and frequency, general analysis code(ANSYS-Mechanical 13) is employed in the present work. Throughout structure analysis in the hybrid street-lamp, maximum stress is observed at the connecting position between a turbine blade and a blade supporter. Campbell diagram which is combined the natural frequency of turbine blades and blade passing frequency is presented to analyze a system resonance. It is found that the resonance of the system having a rotating turbine blade and a lamppost can avoid by the optimal selection of geometric parameters of a wind turbine.

Development of the Multi-Gear Train Devices of Synchro System for the Guns of a Warship which Considered the Noise/Vibration (소음/진동을 고려한 함포용 Synchro System의 다단 기어 구동장치 개발)

  • Lee, Hyoung-Woo;Hur, Nam-Soo;Kim, In-Hwan;Lee, Dong-Hwan
    • Journal of Advanced Marine Engineering and Technology
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    • v.34 no.8
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    • pp.1057-1067
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    • 2010
  • Vibration and noise analysis as well as strength of gear teeth, gear profile design are considered in order to develop the multi-gear train devices of synchro system for the guns of a warship. A new approach to the critical speed calculation of practical industrial multi-mesh geared system is presented. A transfer matrix model based on Hibner's branch method is developed and the natural properties of the branched rotor system are calculated with using the ${\lambda}$-matrix formulation. A Campbell diagram, in which the excitation sources caused by the mass unbalance of the rotors and the transmitted errors of the gearing are considered, shows that, at theoperating speed, there are not the critical speed.