• Title/Summary/Keyword: Torsional Characteristics

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Digital Optimal Contorl of Servomotor System Considering Torsional Vibration Characteristics (비틀림 진동특성을 고려한 서어보모터계의 디지털 최적제어)

  • Jo, Seung-Ho
    • Journal of the Korean Society for Precision Engineering
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    • v.6 no.4
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    • pp.52-60
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    • 1989
  • In order to control the transient torsional vibration of rotational shaft system, the torsional stiffness of it has been taken into account in modelling the plant. In this paper the observer and controller has been designed in two ways. One is to consider the torsional stiffness and the other is to idealize the rotational shaft as rigid body. The third order observer considering torsional stiffness shows stable response on computer simulation. When the observer is designed on assumption of the rotational shaft being rigid body, the reduced order observer shows stable response whereas the full order observer shows unstable response.

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The Effect of Structural Factors on the Torsional Rigidity of Yarns

  • Park, Jung Whan
    • Fashion & Textile Research Journal
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    • v.2 no.5
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    • pp.437-442
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    • 2000
  • In this paper, in order to examine the torsional behaviour of twisted yarn closely, the torsional rigidity would be derived in terms of physical and mechanical characteristics of its constituent fibers and yarn structural parameters by energy-method. And the propriety of the theory will be discussed by comparing with experimental results. The torsional rigidity of yarn in both experimental and theoretical results decreases with surface helix angle increases. But the experimental values are more higher than those of the theoretical ones.

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Effects of coupled translational-torsional motion and eccentricity between centre of mass and centre of stiffness on wind-excited tall buildings

  • Thepmongkorn, S.;Kwok, K.C.S.
    • Wind and Structures
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    • v.5 no.1
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    • pp.61-80
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    • 2002
  • Wind tunnel aeroelastic model tests of the Commonwealth Advisory Aeronautical Research Council (CAARC) standard tall building were conducted using a three-degree-of-freedom base hinged aeroelastic(BHA) model. Experimental investigation into the effects of coupled translational-torsional motion, cross-wind/torsional frequency ratio and eccentricity between centre of mass and centre of stiffness on the wind-induced response characteristics and wind excitation mechanisms was carried out. The wind tunnel test results highlight the significant effects of coupled translational-torsional motion, and eccentricity between centre of mass and centre of stiffness, on both the normalised along-wind and cross-wind acceleration responses for reduced wind velocities ranging from 4 to 20. Coupled translational-torsional motion and eccentricity between centre of mass and centre of stiffness also have significant impacts on the amplitude-dependent effect caused by the vortex resonant process, and the transfer of vibrational energy between the along-wind and cross-wind directions. These resulted in either an increase or decrease of each response component, in particular at reduced wind velocities close to a critical value of 10. In addition, the contribution of vibrational energy from the torsional motion to the cross-wind response of the building model can be greatly amplified by the effect of resonance between the vortex shedding frequency and the torsional natural frequency of the building model.

Improvement of Dynamic Characteristics of Torsion on the Marine Propulsion Shafting System with Elastic Rubber Coupling (고무 탄성커플링을 갖는 선박 추진축계 비틀림의 동특성 개선)

  • Lee, D.C.
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.13 no.12
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    • pp.923-929
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    • 2003
  • As for the marine propulsion shafting system using 4 stroke diesel engine, it is common to apply a reduction gear box between diesel engine and shafting to increase propulsion efficiency, which requires inevitably a certain elastic coupling to avoid chattering and hammering inside of gear box. In this study, the optimum method of rectifying propulsion shafting system in case of 750 ton fishing vessel is theoretically studied in a view of dynamic characteristics of torsion. After the replacement of diesel engine and gear box, the torsional vibration get worse and so some countermeasures are needed. The elastic coupling is modified from a present rubber coupling of block type having relatively high torsional stiffness to a rubber coupling haying two serially connected elements. Torsional vibration damper was installed at crankshaft free end additionally and moment of inertia of flywheel was adjusted. The dynamic characteristics of shafting system was improved by these modification. The theoretical analysis of torsional vibration are compared to measurement results using two laser torsion meters during the sea trial.

Torsional and Warping Constants of I-shaped Plate Girders with a Sine Corrugated Web (Sine 파형 복부판을 갖는 I형 플레이트 거더의 비틂 및 뒴 상수)

  • Kim, Seungjun;Jeon, Jin Su;Won, Deok Hee;Kang, Young Jong
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.32 no.6A
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    • pp.347-354
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    • 2012
  • In this study, the equations of torsional and warping constants of a I-shaped plate girder with sine corrugated web are suggested. Because of geometric characteristics of the section, a I-shaped plate girder with corrugated web shows high out-of-plane stiffness, shear strength, and torsional stiffness. Torsional constant and warping constant definitely affect lateral-torsional buckling loads. Therefore, exact estimation of the sectional properties is quite important. But, it is difficult to estimate these properties by former methods. So, this study was focused on suggestion of the rational equations to calculate torsional and warping constants. In order to investigate the effects of geometric characteristics of sine-corrugated webs on torsional stiffness and warping torsional constant, finite element analyses for pure torsional behavior and warping torsional behavior of I-shaped plate girders were performed. By regression analyses of the analytical results, rational equations of the torsional constant and warping constant were suggested. Suggested equations for the properties were validated based on the analytical results of lateral-torsional buckling of simply supported I-shaped plate girder. By suggested equations, torsional and warping constants of I-shaped plate girders with a sine-corrugated web can be rationally estimated and more exact lateral-torsional buckling load can be simply calculated.

Vibration Characteristics of Piezoelectric Torsional Transducers (압전 비틀림 변환기의 진동특성 해석)

  • Kwon, Oh-Soo;Kim, Jin-O
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2000.06a
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    • pp.1280-1285
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    • 2000
  • The paper deals with a theoretical study on the vibrational characteristics of piezoelectric torsional transducers. The differential equations of piezoelectric torsional motion have been derived in terms of the circumferential displacement and the electric potential. Applying mechanical and electrical boundary conditions has yielded the characteristic equations of natural vibration in several transducer types. Numerical results have clarified the effect of the piezoelectric phenomenon on the mechanical resonance and the effect of the elastic block of a Langevin-type transducer on the natural frequency.

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Vibration Characteristics of Piezoelectric Torsional Transducers (압전 비틀림 변환기의 진동특성 해석)

  • 권오수;김진오
    • Journal of KSNVE
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    • v.10 no.6
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    • pp.955-962
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    • 2000
  • The paper deals with a theoretical study on the vibrational characteristics of piezoelectric torsional transducers. The differential equations of piezoelectric torsional motion have been derived in terms of the circumferential displacement and the electric potential. Applying mechanical and electrical boundary conditions has yielded the characteristic equations of natural vibration in several transducer types. Numerical results have clarified the effect of the piezoelectric phenomenon on the mechanical resonance and the effect of the elastic block of a Langevin-type transducer on the natural frequency.

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Computer Simulation of Powertrain Forced Torsional Vibration (차량주행시 동력전달계의 강제진동 해석)

  • 최은오;안병민;홍동표
    • Journal of KSNVE
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    • v.7 no.5
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    • pp.853-860
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    • 1997
  • For this study, the multi-degree of freedom analysis model of torsional vibration was developed. This model is combined with mass moment of inertia and torsional spring in two wheel drive and four wheel drive vehicle. We compared and analyzed torsional vibration characteristics by natural frequencies and mode shapes which are obtained by free vibration analysis of this model. And we studied torsional vibration contribution of driveline elements by performing the forced vibration analysis of engine excitation torque. The validity of this model is demonstrated by the field test. The reduction effect of the torsional vibration along the driveline design factor is presented by the analytical results.

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Fabrication and Evaluation of Piezoelectric Torsional Transducers (압전 비틀림 파동 변환기 제작 및 평가)

  • Kwon, Oh-Soo;Kim, Jin-Oh
    • Journal of the Korean Society for Nondestructive Testing
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    • v.21 no.4
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    • pp.434-438
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    • 2001
  • Piezoelectric torsional transducers have been fabricated to generate torsional waves in a rod. The principle of generating torsional wane is based on the use of the circumferential shear motion derived by axial voltage exerted on the piezoelectric disk poled in the circumferential direction. The natural frequency or the piezoelctric torsional dish has been reduced by fabricating Langevin-type torsional transducers. The natural frequecies of the fabricated transducers have been measured and have shown good agreement with the characteristics predicted by analysis.

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A Study on the Design of Propeller Shaft for Reduction of Torsional Vibration (비틀림짙동 저감을 위한 추진축 설계에 관한 연구)

  • 최은오;안병민;홍동표;정태진
    • Transactions of the Korean Society of Automotive Engineers
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    • v.7 no.7
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    • pp.221-228
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    • 1999
  • A full-time four wheel drive vehicle is driven literally full time by the front and the rear wheels. Front and rear drive shafts are rotated rapidly in the extremely torsional state, which can cause various vibration and noise problems. The purpose of this study is to reduce the vibration and the noise of the full -time four wheel drive vehicle. In this paper, both the causes and the methods for reduction of torsional vibration are suggested. For this study, the characteristics of the torsional vibration are analyzed by free and forced torsional vibration simulation. And this paper described the influence upon the torsional vibration with emphasis shafting system. The validity of simulation models is checked by the field test. The forced vibration simulation with the variations of shaft design factors are performed by the checked models. According to the simulation , the resonance region shifts and the torque fluctuation varies in the system,. Finally, the methods and the effects for the torsional vibration reduction in driveline are proposed.

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