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Ball Bearing Vibrations Amplitude Modeling and Test ComparisonsBearings generate disturbances that, when combined with structural gains of a momentum wheel, contribute to induced vibration in the wheel. The frequencies generated by a ball bearing are defined by the bearing's geometry and defects. The amplitudes at these frequencies are dependent upon the actual geometry variations from perfection; therefore, a geometrically perfect bearing will produce no amplitudes at the kinematic frequencies that the design generates. Because perfect geometry can only be approached, emitted vibrations do occur. The most significant vibration is at the spin frequency and can be balanced out in the build process. Other frequencies' amplitudes, however, cannot be balanced out.

Momentum wheels are usually the single largest source of vibrations in a spacecraft and can contribute to pointing inaccuracies if emitted vibrations ring the structure or are in the high-gain bandwidth of a sensitive pointing control loop. It is therefore important to be able to provide an a priori knowledge of possible amplitudes that are singular in source or are a result of interacting defects that do not reveal themselves in normal frequency prediction equations. This paper will describe the computer model that provides for the incorporation of bearing geometry errors and then develops an estimation of actual amplitudes and frequencies. Test results were correlated with the model. A momentum wheel was producing an unacceptable 74 Hz amplitude. The model was used to simulate geometry errors and proved successful in identifying a cause that was verified when the parts were inspected.
Document ID
19950020866
Acquisition Source
Johnson Space Center
Document Type
Conference Paper
Authors
Richard A Hightower, III
(Honeywell, Inc. United States)
Dave Bailey
(Honeywell, Inc. United States)
Date Acquired
September 6, 2013
Publication Date
May 1, 1995
Publication Information
Publication: 29th Aerospace Mechanisms Symposium
Publisher: National Aeronautics and Space Administration
Subject Category
Mechanical Engineering
Report/Patent Number
NASA-CP-3293
Meeting Information
Meeting: 29th Aerospace Mechanisms Symposium
Location: League City, TX
Country: US
Start Date: May 17, 1995
End Date: May 19, 1995
Sponsors: Lockheed Missiles and Space Company (United States), National Aeronautics and Space Administration
Accession Number
95N27286
Distribution Limits
Public
Copyright
Portions of document may include copyright protected material.
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