A tuned mass system has a bulk mass acted upon by an excitation amplitude and a reaction mass coupled to the bulk mass. A resistance-to-motion controlled coupling mechanism associated with the reaction mass is configured to proportionally modulate independent of excitation force such that the relative phase of the bulk mass and the reaction mass is substantially constant throughout an extended range of excitation amplitude. The resistance-to-motion controlled coupling mechanism is a Variable Aperture Reciprocating Reed (VARR) Valve in one embodiment, and operates as a passive mechanism. In other embodiments, active resistance-to-motion controlled coupling mechanisms are employed.

A dynamic damper assembly may include a plurality of bodies arranged at predetermined intervals on an outer peripheral surface of a drive shaft, and an elastic body formed to surround each of the bodies and fixing each body to the drive shaft.

Provided is a damper with which the energy efficiency for attenuating input vibration corresponding to the unsprung resonance frequency and the sprung resonance frequency can be improved. Also provided is a method for manufacturing this damper. In this damper the electrical resonance frequency, as specified by the inductance of an electromagnetic motor and the capacitance of a capacitor, is set within ±20% of the unsprung resonance frequency, thereby enabling the input vibration corresponding to the sprung resonance frequency as well as the input vibration corresponding to the unsprung resonance frequency to be reduced.

A compound helicopter includes a fuselage including a fuselage airframe, a translational thrust system coupled to the fuselage airframe and a pylon assembly subject to vibration. The pylon assembly includes a transmission and a rotor system having a main rotor assembly. The compound helicopter also includes a main rotor vibration isolation system including a plurality of augmented liquid inertia vibration eliminator units each having an isolation frequency and each coupled between the fuselage airframe and the pylon assembly to reduce transmission of the pylon assembly vibration to the fuselage airframe at the isolation frequency. Each augmented liquid inertia vibration eliminator unit includes at least one active tuning element movable to tune the isolation frequency thereof.

A steering wheel damper may include a plate fastened to a hub of a steering wheel; one or more posts each having one side fixed to a surface of the plate and the other side extending perpendicular to the surface of the plate; a mass body spaced from the plate, attached to the other side of the post, supported by the posts, and having upper and lower portions configured as magnet bodies having different polarities; and an electromagnet made by winding a coil around a core fixed to the surface of the plate.

A dual-frequency vibration-reduction apparatus includes a beam having a longitudinal axis and a transverse axis perpendicular to the longitudinal axis. An attachment mechanism mechanically couples a portion of the beam to a structure. One or more masses are attached to the beam such that the apparatus vibrates bi-modally at a primary frequency and a secondary frequency for reducing vibrations of the structure at the primary frequency and the secondary frequency. A first mode may be a bending mode of the apparatus, while a second mode is a torsion mode. The vibration reduction apparatus may be tuned such that the primary frequency substantially matches a blade-pass frequency of a propeller-driven aircraft and the secondary frequency substantially matches a harmonic of the blade-pass frequency. The vibration reduction apparatus includes a mounting mechanism for mounting to any structure requiring low-frequency vibration attenuation.

A shock absorber assembly comprises a main tube disposed on a center axis between a first and a second end and defining a fluid chamber extending therebetween. A first piston is slidably disposed in the fluid chamber dividing the fluid chamber into a compression chamber and a rebound chamber. A piston rod attaches to the first piston for moving the first piston between a compression stroke and a rebound stroke. A hydraulic compression stop includes a second piston located in the compression chamber and attached to the piston rod. A tenon couples to the piston rod, located between the first piston and the second piston. The tenon includes a frequency dependent damping valve coupled to the first piston and an enclosure extending about the frequency dependent damping valve, coupled to the frequency dependent valve and the second piston, in fluid communication with the compression chamber.

Proposed is a rubber bush type vibration damping device for a vehicle, which solves the problem of vibration increase which may occur in the natural frequency of the vibration damping device by changing the shapes of an inner coupling part or an outer coupling part and by using difference in the lengths of rubber insulators due to the changing of the shapes thereof. The vibration damping device includes an inner coupling part, an outer coupling part, and a plurality of rubber insulators having have different natural frequency.

A damping force adjustable shock absorber includes a flow path (an oil passage of a piston) in which a flow of hydraulic fluid is generated due to a movement of a piston rod, and a damping force adjustment valve provided in the flow path and configured to be subjected to an adjustment of an opening/closing operation by a solenoid. A frequency adaptive mechanism is provided in the flow path in series with the damping force adjustment valve. The frequency adaptive mechanism is configured to reduce a damping force for a high-frequency vibration. The frequency adaptive mechanism includes a second valve mechanism (a compression-side damping force generation valve and an extension-side damping force generation valve) configured to apply a resistance force to a flow of the hydraulic fluid from an upstream-side chamber (an upper-portion chamber or a lower-portion chamber) to a downstream-side chamber (the lower-portion chamber or the upper-portion chamber).

A damper assembly includes a housing having a tubular shape defining a main chamber extending along a center axis. A piston is movable along the center axis and divides the main chamber into a compression chamber and a rebound chamber. The piston includes a piston body defining a frequency-adaptive orifice (FAO) passage providing fluid communication between the compression chamber and the rebound chamber. The piston includes an FAO valve assembly having an FAO cover member configured to block fluid flow therethrough in response to application of a low-frequency excitation, and allowing fluid flow through the FAO passage in response to application of a high-frequency excitation. The FAO valve assembly also includes a tappet configured to translate relative to the piston body to bias the FAO cover member to selectively cover the FAO passage in response to the application of the low-frequency excitation.