The present invention refers to a mass damper for reducing vibrations of a structure with a pendulum mass and a damping means, wherein the mass damper has at least three bearings with which the pendulum mass is movably supported on the structure such that it can execute pendulum movements and each of the bearings has at least one pendulum plate with a concave bearing surface and a sliding shoe arranged movably thereon with a convex counter surface. In accordance with the invention, the bearing surfaces and the associated counter surfaces are curved with a constant radius of curvature R and all bearings have a lowest possible friction between the counter surface and the bearing surface. The invention also extends to a structure with such a mass damper and a method for adjusting the natural frequency of a mass damper, in which the natural frequency of the pendulum mass can be adjusted independently of one another in both main directions by displacing and/or rotating the pendulum plates. The invention also extends to the damping means, which can be implemented with linear viscous passive damping, with square viscous passive damping or with controlled damping, in order to tune this damping together with the friction damping of the bearings to the optimum damping of the mass damper.

An active vibration isolation system for isolating a suspended platform from vibration input to the vibration isolation system base includes an exoskeleton, a rotary actuator, and a drive mechanism separate from the exoskeleton for providing force output from the rotary actuator to the suspended plant. The rotary actuator may include inner and outer rotors which rotate relative to each other. The rotary actuator may be free to translate relative to the vibration isolation system base and the suspended platform, and both the inner and outer rotors may be free to rotate relative to the exoskeleton.

This disclosure relates to an active inerter damper configured to be disposed on or in a building structure. The active inerter damper includes a base, a lead screw, a rotational mass block, a driving device and a controller. The lead screw is movably disposed above the base along an axial direction. The rotational mass block is engaged with the lead screw so as to be rotatable with respect to the base. The driving device is connected to the lead screw. The controller is electrically connected to the driving device, and the controller is configured to activate the driving device to move the lead screw along the axial direction so as to rotate the rotational mass block via the lead screw.

An impulse damper device, which is specifically provided for the construction or the dismantling of tall, slim constructions, in particular towers and preferably towers of wind turbines, in order to minimize or eliminate undesired vibration states, which often occur during the construction or taking apart and lead to large increases in the vibration amplitudes of the vibration system. The impulse tuned mass dampers are preferably provided for temporary mobile use, but, in principle, are also suitable for permanent use.

Inerters with friction disk assemblies, and aircraft hydraulic systems and aircraft including the same. An inerter comprises an inerter housing containing an inerter fluid, a threaded shaft extending within the inerter housing and fixed relative to the first terminal, and an inerter rod extending at least partially within the inerter housing and fixed relative to the second terminal. The inerter further includes a friction disk assembly that, together with the inerter fluid, is configured to damp a motion of the second terminal relative to the first terminal. The friction disk assembly includes a fixed portion and a rotating portion, and is configured such that rotation of the rotating portion generates a frictional torque that opposes the rotation of the rotating portion. In some examples, the inerter is a component of a hydraulic actuator, an aircraft hydraulic system including the hydraulic actuator, and/or an aircraft including the aircraft hydraulic system.

A system and method are provided for reducing vibrations and loads in one or more rotor blades on a rotor hub of a wind turbine when the rotor hub is in a locked or idling condition. A mass damper is attached at a fixed location on one or more of the rotor blades and is maintained on the rotor blades during the locked or idling condition of the rotor hub. The mass damper includes a movable mass component that is responsive to changes in the vibrations or oscillations induced in the rotor blades during the locked or idling condition of the rotor hub.

A system and method include with a mass damper for reducing vibrations in a structure or machine. The mass damper includes a frame that is movable linearly along a base, which includes a track gear. A flywheel is in geared engagement with the track gear so as to be rotationally driven as the frame moves linearly relative to the base. A rotation damper is mounted on the frame and is geared engagement with the flywheel, the rotation damper producing a counter-torque against rotation of the flywheel that is proportional to a rotational velocity of the flywheel. The rotation damper has an electrical characteristic that is automatically adjusted to change the counter-torque and tune the mass damper.

Systems, devices, and methods for active vibration control using circular force generators. In one aspect, a vehicle includes a vehicle frame, a cabin, an engine, and a number of vibration control devices mounted on the vehicle frame. Each vibration device includes a circular force generator comprising at least one mass and at least one motor configured to rotate the mass. The vibration control devices are configured to perform active vibration control to reduce noise and/or vibration within the cabin resulting from the engine deactivating a subset of cylinders in operation.

A kit for a helicopter is described, the helicopter comprising a fuselage and a rotor; the kit comprises at least one device adapted to dampen the vibrations transmitted from the rotor to the fuselage and to be interposed between the fuselage and the rotor; the device, in turn, comprises a first threaded element operatively connectable to the rotor and adapted to, in use, vibrate parallel to a first axis; a second threaded element operatively connectable to the fuselage and operatively connected to the first threaded element so as to, in use, rotationally vibrate about the first axis; and a plurality of threaded rollers, which are screwed on the first and second threaded elements; the rollers being rotatable about their respective second axes parallel to and separate from the first axis with respect to the first and second threaded elements; the rollers are also rotatable about the first axis with respect to the first threaded element and the second threaded element.

Rotational translation of an inertial mass rotor is used for providing damping of low frequency noise and vibration. An axial component is mounted so as to translate axial movement of an inertial linearly-displaceable member to rotational movement of an inertial mass rotor. The translation to rotational movement of the inertial mass rotor provides inertial amplification in the form of translational-rotational coupling. This enables the construction of a compact assembly, which allows light ultra-low frequency resonances to be concentrated, and which absorbs such low frequency noise energy.