Active Stiffness Control of Cable Vibration

To suppress cable vibrations, active stiffness control, which changes the tension as a positive use of parametric excitation, is studied. An optimal algorithm is obtained from energy analysis and verified by experiment on a scale model. Numerical investigation is then made on the control of a combined system of cable and single-degree- of-freedom structure; the degree-of-freedom of the latter is along the cable axis. It is found by numerical simulation that instability occurs when the mass ratio of cable to structure is large, or when the frequency ratio of structure to cable is close to 2.0.

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Study on Applicability of Equivalent Single Degree of Freedom Methods for Single Column Pier with Uniform Cross Section

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.255-260.1716 ◽

2011 ◽

Vol 255-260 ◽

pp. 1716-1720

Author(s):

Liang Chen

Keyword(s):

Cross Section ◽

Fundamental Mode ◽

Degree Of Freedom ◽

Mass Ratio ◽

Shape Functions ◽

Single Degree Of Freedom ◽

Single Degree ◽

Single Column ◽

Simplified Method ◽

Uniform Cross Section

Applicability of the simplified method based on equivalent single-degree-of-freedom (ESDOF) for single-column pier with uniform cross-section is investigated in this paper. The modal participating mass ratio of pier’s fundamental mode is taken as an index to evaluate the applicability of the simplified method. Based on the fundamental mode shape functions selected deliberately in the first step, equations to evaluate the modal participating mass ratio of pier fundamental mode is obtained. Using the proposed equations, it is convenient to evaluate applicability of the simplified method with the height of the pier and the ratio of the linear mass along the column to the dumped mass at the top of the pier. Finally, the index is verified in the different nonlinear range of piers.

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Vibration of Satellite Subsystem During Orbiter Lift-Off

International Journal of Space Structures ◽

10.1177/026635119300800302 ◽

1993 ◽

Vol 8 (3) ◽

pp. 167-176 ◽

Cited By ~ 1

Author(s):

Gina Lee-Glauser ◽

Goodarz Ahmadi

Keyword(s):

Response Spectra ◽

Degree Of Freedom ◽

Mass Ratio ◽

Acceleration Response ◽

Single Degree Of Freedom ◽

Lump Parameter Model ◽

Single Degree ◽

Acceleration Response Spectra ◽

Lift Off ◽

Sinusoidal Excitation

Vibrations of a satellite and one of its sensitive subsystems during orbiter lift-off are studied. A single degree-of-freedom representation of the subsystem and a five degree-of-freedom lump parameter model of the satellite are considered. Deflection and acceleration response spectra of the satellite and its subsystem subject to sinusoidal excitation and the STS - 41 lift-off accelerations are evaluated. The significance of the subsystem and primary satellite interaction is investigated. The effect of mass ratio and damping coeficient of the subsystem on the peak deflection and acceleration response spectra of the satellite and its subsystem are examined.

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On the Critical Speed of Continuous Shaft-Disk Systems

Journal of Vibration and Acoustics ◽

10.1115/1.3269154 ◽

1984 ◽

Vol 106 (1) ◽

pp. 59-61 ◽

Cited By ~ 19

Author(s):

H. Nevzat O¨zgu¨ven

Keyword(s):

Critical Speed ◽

Degree Of Freedom ◽

Mass Ratio ◽

Disk System ◽

Single Degree Of Freedom ◽

Single Degree

The critical speed of a shaft-disk system can be approximately determined from a single degree-of-freedom model. The errors in the critical speed predictions obtained from such a model are investigated. The percentage errors are plotted against disk to shaft mass ratio for different bearings and various disk locations.

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The Stabilization of a North-Seeking Platform Using a Dynamically Tuned Hooke’s Joint Gyroscope

Journal of Applied Mechanics ◽

10.1115/1.3153597 ◽

1980 ◽

Vol 47 (1) ◽

pp. 167-171 ◽

Cited By ~ 3

Author(s):

J. S. Burdess ◽

C. H. J. Fox

Keyword(s):

Dynamic Response ◽

Degree Of Freedom ◽

Combined System ◽

Single Degree Of Freedom ◽

Single Degree ◽

Mass Unbalance ◽

Hooke’S Joint ◽

The Ideal

The paper shows that the ideally tuned Hooke’s joint gyroscope is capable of operating as a gyrocompass. The dynamic response of the compass is examined in detail and its accuracy as a north-seeking device is assessed. It it shown that small amounts of mistuning will result in gross errors. The need for precision tuning is eliminated by supporting the gyroscope on a single-degree-of-freedom platform. It is shown that if the platform is driven via feedback of the gyrorotor displacement in azimuth then the response of the combined system is essentially that of the ideal gyroscope. The overall system is insensitive to misturning errors and will automatically align the gyrospin axis with true north irrespective of any initial offset. The effects of damping, mass unbalance, and platform misalignment are assessed.

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