Tunable vibration noise reducer with spherical element containing tracks
AssigneeNorthrop Grumman Corporation
InventorsJamil I. Lahham, Lloyd S. Sikes, Stephen J. Ryan
Life of this patent
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Abstract
A tunable mass coupled to a body subjected to forced vibrations that reduces the vibration amplitudes of the body in the forced vibration frequency band. The mass includes a container having a plurality of cavities with grooves in the lower surfaces and notched side walls. Each cavity is filled with spherical elements which are restrained by the grooves and notches. The tunable mass is constructed to respond in a spring like manner so that vibration frequencies of the mass are tunable to provide counter vibrations in the forced vibration frequency band. Vibration frequency amplitude reduction is provided by vibrations of the mass that are in phase opposition to the vibrations of the body.
Claims12
A method for reducing forced vibrations of a body within a vibration frequency band having a first band end and a second band end comprising the steps of:
- constructing a an auxiliary mass with a base plate, said base plate having a multiplicity of cavities, each cavity having a base, and side walls;
- forming grooves in said base and notches in said side walls;
- positioning spherical elements in said cavities in a manner to be constrained by said grooves and notches, said auxiliary mass with said cavities filled with said spherical elements being a mass that vibrates in response to applied external forces;
- and
- coupling said auxiliary mass to said body to form a composite structure such that said composite structure, when subjected to a forcing frequency, vibrates at frequencies within said vibration frequency band with vibration amplitudes that are lower than vibration amplitudes of said body without said coupling of said mass.
An apparatus for reducing forced vibrations of a body comprising:
- an auxiliary mass that vibrates in response to external forces having a plurality of cavities, each cavity having a base and side walls, said base having grooves and said side walls having notches therein, said auxiliary mass constructed and arranged for coupling to said body;
- spherical elements positioned in each of said cavities in a manner to be restrained by said grooves and said notches;
- whereby, when said auxiliary mass is coupled to said body, a composite structure is formed which, when subjected to external forces, vibrates with amplitudes that are lower than vibration amplitudes of said body without said auxiliary mass.
Dependencies are inferred from the claim text.