A vibration suppression unit for an aircraft comprising a vibration control frame adapted to be mounted to the aircraft and to rotate about a central axis, a first motor configured to rotate the vibration control frame about the central axis, a second motor configured to rotate a first and second center of mass about a first and second axis or rotation, a third motor configured to adjust a variable distance between the first and second centers of mass and the first and second axis of rotation, respectively, and a controller for receiving input signals and outputting command signals to the first, second and third motors.

A damper position-limiting device is provided, which is mounted in a tower to limit the swing amplitude of a damper installed in the tower. The damper position-limiting device includes at least one web and a position-limiting ring. The web is provided with a mounting hole and at least one stress relief hole. A first side wall of the web has a first specified length along a circumferential direction of the inner wall of the tower, and is connected to the inner wall of the tower. The position-limiting ring is positioned within the mounting hole and connected to the mounting hole and is configured to accommodate an impacting plate of the damper.

A directional vibration control apparatus, which includes a tunable vibration absorber (TVA) for a vibratory compactor machine is provided. The TVA includes a frame mounting structure that is configured to mechanically interface with a frame of the vibratory compactor to provide a fixed attachment of the TVA to the frame of the vibratory compactor, a TVA carrier that extends from the frame mounting structure into an interior portion of a drum of the vibratory compactor machine, a resilient element that includes a first portion that is fixedly attached relative to the TVA carrier and a second portion that includes a degree of freedom of movement relative to the TVA carrier, and a mass that is attached to the second portion of the resilient element and that includes the degree of freedom of movement relative to the TVA carrier.

A device for damping vibrations in a structure including a first (or inner) element rotatably mounted around a rotational axis and a second (or outer) element rotatably mounted around said rotational axis. A radius (R1) of a circle portion delimitating the first element with respect to the rotational axis, being smaller than a radius (r2) of a circle portion delimitating the second element with respect to the rotational axis.

A passive oscillation damper (8), in particular for a switch cabinet (2), includes a supporting structure (12) having a longitudinal direction (y) and a transverse direction (x) and with a central oscillating mass (14) mounted by means of spring elements (20, 22, 24, 26) so as to be able to oscillate in the longitudinal direction (y) and in the transverse direction (x). At least one peripheral oscillating mass (40, 42) is mounted on the central oscillating mass (14) so as to be slidable in the longitudinal direction (y) and to be movable relative to the central oscillating mass (14). At least one peripheral oscillating mass (44, 46) is mounted on the central oscillating mass (14) so as to be slidable in the transverse direction (x) and to be movable relative to central oscillating mass (14).

A mass damper for a refrigerant pipe is configured to insulate vibration and noise of the refrigerant pipe for the flow of a refrigerant circulating in a vehicle air conditioner system and a mass damper for a vehicle air conditioner system is configured to prevent an external circumferential surface of a casing from cracking due to thermal deformation.

A mass damper for a refrigerant pipe is configured to insulate vibration and noise of the refrigerant pipe for the flow of a refrigerant circulating in a vehicle air conditioner system and a mass damper for a vehicle air conditioner system is configured to prevent an external circumferential surface of a casing from cracking due to thermal deformation.

The invention discloses an active vibration or sound absorption method with virtual resonators exclusively using sensing electromagnetic coil's current and voltage. The invention includes an absorption actuator, a sensing module of coil's current and voltage, an absorption controller, and a driving module. The method controls the coil current's phase to be orthogonal to the actuator velocity's phase, to adjust the resonant frequency of the actuator, such that the signal to be absorbed causes a resonance in the actuator. In this way, a virtual resonator is formed. Moreover, one actuator can generate multiple virtual resonators simultaneously to absorb energy of multiple signals with different frequencies, and the resonant frequency and its damping ratio for each virtual resonator can be adjusted independently.

An arrangement reduces oscillation (vibration) of an oscillatory structure. The arrangement has a structure having at least one mode in at least one direction; and an oscillation-reducing device (vibration-reducing device). The oscillation-reducing devices has a housing formed by or provided on the structure, a cavity, and a body configured for making impact contacts with the housing and disposed in the cavity in such a manner that the body is configured to make impact contacts with the housing at least temporarily for as long as the structure is excited in the at least one mode in the at least on direction.

Apparatus and methods to reduce unwanted motion in precision instruments are described. An active vibration-isolation system may include a feedback loop that senses motion of an intermediate mass. In noisy environments, where the feedback loop would otherwise fail or provide inadequate isolation, feedforward control can be implemented to sense floor vibrations and reduce motion of the intermediate mass that would otherwise be induced by the floor vibrations. The feedforward control can reduce motion of the intermediate mass to a level that allows the feedback loop to operate satisfactorily.