Showing papers on "Active vibration control published in 1976"

Active vibration damper with electrodynamic sensor and drive units

Abstract: An electrodynamic sensor unit and a drive unit are attached to a member subject to vibration. The sensor unit provides a signal proportional to the vibration velocity, and this signal is utilized to govern the operation of the drive unit, which acts to reduce the vibration amplitude.

Complex vibration tester

Abstract: A mechanical complex vibration tester is provided which is capable of simultaneously applying a plurality of discrete frequencies to a workpiece positioned on a test surface of the device to simulate random vibration testing. The vibrations may be varied in amplitude and they may be applied in either the vertical or the horizontal direction. Means are provided for isolating the tester from its environment in order to simulate vibration testing in inertial space.

Suppression of Rotor-Bearing System Vibrations Through Flexible Bearing Support Damping

Abstract: A bearing damper, operating on the support flexure of a pivoted pad in a tilting-pad type gas-lubricated journal bearing, has been designed, built, and tested under externally applied random vibrations. A 36,000 rpm, 10 Kwe turbogenerator had previously been subjected to external random vibrations, and vibration response data had been recorded and analyzed for amplitude distribution and frequency content at a number of locations in the machine. Based upon data from that evaluation, a piston-type damper was designed and developed for each of the two flexibly-supported journal bearing pads (one in each of the two three-pad bearings). A modified turbogenerator, with dampers installed, has been retested under random vibration conditions. Root-mean-square vibration amplitudes were determined from the test data, and displacement power spectral density analyses have been performed. Results of these data reduction efforts have been compared with vibration tolerance limits and previously reported response characteristics of the unmodified machine. Results of the tests indicate significant reductions in vibration levels in the bearing gas-lubricant films, particularly in the rigidly mounted pads. The utility of the gas-lubricated damper for limiting rotor-bearing system vibrations in high-speed turbomachinery has thus been demonstrated.