Machine vibration often originates with rotating driveline components such as rotors, gears, bearings, and fans. Such vibration is the source of unwanted noise and can be destructive to the machine. The vibration ring is a mechanism that provides an indirect damping effect, and is rigid enough to be mounted within the driveline. The mechanical structure of the vibration ring responds to vibratory excitation by stressing an embedded piezoelectric material. The material generates an electric charge, which is dissipated though an electric circuit. The net result is a reduction of vibration energy.

A concept drawing (left) shows the three core elements of the Vibration Ring: the compression cage, piezoelectric material, and electric circuit. At right is a photograph of a prototype vibration ring.
The vibration ring is a unique, ring-shaped mechanism that indirectly provides a vibration damping effect by converting applied vibratory energy into electricity, and then into heat. The mechanism is self-contained, installed like an ordinary metal spacer, and requires no external wiring. Unlike traditional vibration damping elements (e.g., those made of rubber), the vibration ring is very stiff, and can be used in a mechanical driveline without disrupting the operation or position tolerances of the mechanical assembly. By including this damping element within the driveline, vibration is attenuated before it is able to manifest as noise elsewhere in the machine.

The vibration ring’s compression cage is a ring-shaped mechanical amplifier. Forces imparted at any position around its perimeter are transferred into the axial direction. This allows the use of piezoelectric and other anisotropic materials, which are optimized to convert vibration energy along one axis. The vibration ring attenuates vibration energy with very little deformation, making it appropriate for use within the driveline of a rotating machine.

The vibration ring effectively serves as an energy sink, which can be placed in close proximity to rotating vibration sources within a machine driveline. It is therefore able to reduce the total vibration transfer from the driveline to the rest of the machine.

This work was done by Vivake Asnani of Glenn Research Center.

Inquiries concerning rights for the commercial use of this invention should be addressed to NASA Glenn Research Center, Innovative Partnerships Office, Attn: Steven Fedor, Mail Stop 4–8, 21000 Brookpark Road, Cleveland, Ohio 44135. Refer to LEW-19132-1.


NASA Tech Briefs Magazine

This article first appeared in the September, 2014 issue of NASA Tech Briefs Magazine.

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