Dynamic damper for offshore structures

Claim 2

Means for controlling the oscillation of a marine structure induced by the action of waves on said structure comprising a structure positioned in a substantially fixed condition in a body of water and extending vertically through said water to the surface thereof and exposed to wave forces which induce said structure to oscillate, an auxiliary mass connected to said structure, means mounting said mass on said structure for movement relative to said structure when said structure is oscillated, and restraining means operatively connected to said mass to resist said movement of said mass relative to said structure, said mass and said restraining means being operatively arranged to absorb and dissipate energy from said structure as said structure is induced to oscillate to thereby reduce the amplitude of oscillation of said structure.

Claim 3

Apparatus in accordance with claim 1 in which said auxiliary mass is a pendulum mounted on said structure for swinging movement relative thereto when said structure is oscillated by said wave forces, and wherein said restraining means is a body of fluid arranged to resist the swinging movement of said pendulum.

Claim 4

Apparatus in accordance with claim 2 in which said pendulum is supported by a gimbal to permit said pendulum swing in a direction which is responsive to a varying direction of oscillation of said structure.

Claim 5

Apparatus in accordance with claim 2 including means for adjusting the effective length of said pendulum whereby the period of said pendulum may be adjusted to correspond to the period of said oscillation of said structure.

Claim 6

Means for damping vibrations of a marine structure induced by the action of the water waves comprising a structure positioned in a body of water and extending from a fixed seat at the bottom of said body of water to the surface thereof and subjected to wave forces which induce said structure to vibrate, a support means fixedly attached to said structure to vibrate therewith, a bearing means supported by sAid support means, a pendulum means connected to said bearing means for swinging movement relative to such structure and mounted to be swung by vibrations induced in said structure, restraining means interposed between said pendulum means and said structure to resist said swinging movement of said pendulum means relative to said structure, said pendulum and said restraining means being operatively arranged to absorb and dissipate energy from said structure as said structure is induced to vibrate.

Claim 7

Means for damping vibrations of a marine structure induced by the action of the water waves comprising a structure positioned in a body of water and extending from a fixed seat at the bottom of said body of water to the surface thereof and subjected to wave forces which induce said structure to vibrate, a support means fixedly attached to said structure to vibrate therewith, a bearing means supported by sAid support means, a pendulum means connected to said bearing means for swinging movement relative to such structure and mounted to be swung by vibrations induced in said structure, restraining means interposed between said pendulum means and said structure to resist said swinging movement of said pendulum means relative to said structure, said pendulum and said restraining means being operatively arranged to absorb and dissipate energy from said structure as said structure is induced to vibrate.

Claim 8

Apparatus in accordance with claim 4 comprising a plurality of said support means attached to said structure in spaced-apart relationship to each other, a respective said bearing means supported by each of said support means, and a respective said pendulum means connected to each of said bearing means.

Claim 9

Apparatus in accordance with claim 5 wherein said restraining means comprises a first plate means connected to said structure to be stationary relative thereto, a second plate means connected to said pendulum means for movement therewith and disposed in adjacent spaced-apart relationship to said first plate means, and a damping liquid placed between and in mutual contact with said first and said second plate means to provide a resisting medium which resists relative motion between said first and said second plate means.

Claim 10

Apparatus in accordance with claim 7 wherein said first plate means is connected to said support means and is formed as a portion of a sphere having a center coincident with the center of said swinging movement of said pendulum, and wherein said second plate means is formed as a portion of a sphere and is affixed to said pendulum in concentric relation-ship to said first plate means.

Claim 11

Means for controlling the vibrations of a marine structure induced by wave forces acting on said structure comprising a structure positioned in a body of water and anchored in a substantially fixed location and exposed to wave forces which induce said structure to vibrate, an auxiliary mass, means connecting said mass to said structure for movement relative to said structure when said structure vibrates, and restraining means operatively connected to said mass to resist said movement of said mass relative to said structure, said mass and said restraining means being operatively arranged to absorb and dissipate energy from said structure as said structure is induced to vibrate to thereby reduce the amplitude of vibration of said structure.

Claim 12

Means for controlling the vibrations of a marine structure induced by wave forces acting on said structure comprising a structure positioned in a body of water and anchored in a substantially fixed location and exposed to wave forces which induce said structure to vibrate, an auxiliary mass, means connecting said mass to said structure for movement relative to said structure when said structure vibrates, and restraining means operatively connected to said mass to resist said movement of said mass relative to said structure, said mass and said restraining means being operatively arranged to absorb and dissipate energy from said structure as said structure is induced to vibrate to thereby reduce the amplitude of vibration of said structure.

Claim 13

Apparatus in accordance with claim 9 in which said auxiliary mass is a pendulum mounted on said structure for swinging movement relative thereto when said structure is vibrated by said wave forces, and wherein said restraining means is a body of fluid arranged to resist said swinging movement of said pendulum.

Claim 14

Means for controlling the forced synchronous vibrations of a marine structure induced by the action of wave forces on said structure comprising a structure arranged to be placed in a body of water in a substantially fixed position in relation to the underwater bottom and exposed to wave forces which induce said structure to vibrate, an auxiliary mass, means connecting said mass to said structure and permitting movement of said mass relative to said structure when said structure vibrates, restraining means for resisting movement of said mass relative to said structure, said mass and said restraining means being operatively arranged to absorb and dissipate energy from said structure as said structure is induced to vibrate thereby to reduce the amplitude of vibration of said structure.

Claim 15

Means for controlling the forced synchronous vibrations of a marine structure induced by the action of wave forces on said structure comprising a structure arranged to be placed in a body of water in a substantially fixed position in relation to the underwater bottom and exposed to wave forces which induce said structure to vibrate, an auxiliary mass, means connecting said mass to said structure and permitting movement of said mass relative to said structure when said structure vibrates, restraining means for resisting movement of said mass relative to said structure, said mass and said restraining means being operatively arranged to absorb and dissipate energy from said structure as said structure is induced to vibrate thereby to reduce the amplitude of vibration of said structure.

Claim 16

In combination, a structure arranged to be positioned in a body of water in a relatively fixed position in relation to the underwater bottom and exposed to forces which will induce said structure to vibrate, an auxiliary mass mounted on said structure for movement relative to said structure when said structure vibrates, restraining means for resisting said movement of said mass relative to said structure, said mass and said restraining means being operative to absorb energy from said structure as said structure is induced to vibrate, said mass and said restraining means being proportioned and arranged to limit the amplitude of vibration of said structure within a predetermined limit.

Claim 17

In combination, a structure arranged to be positioned in a body of water in a relatively fixed position in relation to the underwater bottom and exposed to forces which will induce said structure to vibrate, an auxiliary mass mounted on said structure for movement relative to said structure when said structure vibrates, restraining means for resisting said movement of said mass relative to said structure, said mass and said restraining means being operative to absorb energy from said structure as said structure is induced to vibrate, said mass and said restraining means being proportioned and arranged to limit the amplitude of vibration of said structure within a predetermined limit.

Claim 18

A combination in accordance with claim 12 in which said auxiliary mass is a pendulum mounted on said structure for swinging movement relative thereto, and wherein said restraining means is a body of fluid arranged to resist said swinging movement.

Claim 19

In combination, a structure located in a body of water and maintained in a relatively fixed position in relation to the underwater bottom, said structure exposed to forces which induce said structure to vibrate, an auxiliary mass, means connecting said mass to said structure and constructed to permit movement of said mass relative to said structure as said structure vibrates, restraining means for resisting said movement of said mass relative to said structure, said mass and said restraining means being operatively arranged to absorb energy from said structure as said structure is induced to vibrate to thereby reduce the amplitude of the vibration induced in said structure.

Claim 20

In combination, a structure located in a body of water and maintained in a relatively fixed position in relation to the underwater bottom, said structure exposed to forces which induce said structure to vibrate, an auxiliary mass, means connecting said mass to said structure and constructed to permit movement of said mass relative to said structure as said structure vibrates, restraining means for resisting said movement of said mass relative to said structure, said mass and said restraining means being operatively arranged to absorb energy from said structure as said structure is induced to vibrate to thereby reduce the amplitude of the vibration induced in said structure.