A system for passive damping of mechanical vibrations generated by a vibrating structure supported by a support, including a transducer interposed between the vibrating structure and the support to transform mechanical energy of vibrations into electrical energy. The transducer includes a flextensional structure having a first axis perpendicular to a second axis, a stack of piezoelectric elements adapted to produce electrical energy when stressed, the stack stressed in compression by the flextensional structure along the first axis so that deformation of the structure modifies the compressive stress applied to the stack, two peripheral fasteners are secured to the flextensional structure, each fastener disposed along the second axis, a first fastener for securing the flextensional structure to the vibrating structure, a second fastener for securing the flextensional structure to the support, at least one fastener integrates an elastic suspension, a shunt connected to the piezoelectric stack to dissipate electrical energy.

A vehicle tire assembly having a plurality of flexible spoke portions that extend from an outer annular ring to and inner annular ring. Adjacent pairs of the flexible spoke portions define a plurality of gaps therebetween. A plurality of electro-active members, are disposed radially inward from the outer annular ring and radially outward of the inner ring. The plurality of electro-active members are configured such that in the absence of an electric current flowing therethrough, the plurality of electro-active members flex in response to flexing of the plurality of flexible spoke portions. In the presence of an electric current flowing through the plurality of electro-active members, the plurality of electro-active members become more rigid and less flexible adding corresponding stiffness to the plurality of flexible spoke portions.

The present application relates to self-adjusting damping vibration absorbers, in particular to a self-adjusting damping vibration absorber for while-drilling instruments and an adjusting method thereof. The self-adjusting damping vibration absorber includes a vibration monitor and controller tool and a vibration absorber body. The vibration monitor and controller tool is mounted inside the downhole while-drilling instrument, one end of the vibration absorber body is connected to the vibration monitor and controller tool through an insulating connector, the joint is provided with an insulating pad, the other end is connected to a sensor or circuit board tool that needs vibration damping, and the inside of the vibration absorber body is provided with a damping adjustment layer made of an electroactive polymer. By controlling the magnitude of an applied voltage, the damping adjustment can be realized, and the damping adjustment layer has the characteristics of high response speed and high control precision. The self-adjusting damping vibration absorber of the present application can adjust the vibration absorber damping according to the changes of the downhole vibration and temperature, so that the vibration absorber inherent frequency avoids or is far away from the vibration frequency of the downhole while-drilling instrument so as to avoid resonance, and thereby, the vibration absorber achieves the best vibration damping effect.

The present invention discloses an electromagnetic-piezoelectric composite vibration control device based on a synchronized switch damping technology, and relates to the technical field of vibration abatement. An upper rigid frame is arranged at the upper part of a lower rigid frame, an upper guiding component is installed inside the upper rigid frame, a lower guiding component is installed inside a lower rigid component, a guide rod is nested inside the upper guiding component and the lower guiding component, a load platform is fixed to the upper end of the guide rod, an upper idler wheel mechanism and a lower idler wheel mechanism are fixedly sleeved on the guide rod and are positioned between the upper guiding component and the lower guiding component respectively, an electromagnetic mechanism is fixedly sleeved outside the guide rod, an elastic component is sleeved outside the lower idler wheel mechanism, one end of each piezoelectric cantilever beam is fixed between the upper rigid frame and the lower rigid frame, the other end of each piezoelectric cantilever beam is arranged between the upper idler wheel mechanism and the lower idler wheel mechanism, and the piezoelectric cantilever beams and the electromagnetic mechanism are connected with a circuit system respectively. The device is simple in structure and reliable in performance, a voltage source does not need to be provided externally, and the device is of an adaptive characteristic.

A built-in piezoelectric type online dynamic balance actuator which includes two structurally identical left and right piezoelectric drive adjustment mechanisms at two sides of a housing. The piezoelectric drive adjustment mechanism includes a shaft having one end supported inside a housing chamber by bearing, a middle portion connected to an end cover by bearing, and the other end supported on bearing housing by bearing, a weight mass coupled to the shaft and positioned inside a tightening sleeve with one side connected to the bearing housing and another side connected to the end cover and the housing, and a stator fixedly connected to one side of the end cover, a mover pressed against a surface of the stator through a disk. Through a control center, the mass weights of the left and right piezoelectric drive adjustment mechanisms are fixed to a preset angle. As the main shaft rotates at a high speed, the two weight masses generate centrifugal force which combine to a balance vector to cancel the imbalance vector of the main shaft, improve the mass distribution of the main shaft and better fit the online dynamic balance requirements.

An example cantilever assembly includes a cantilever including an anchor configured to be coupled to a support, a tip, and an arm positioned between the anchor and the tip, a hollow conductive tube positioned at the tip of the cantilever, and a magnet suspended inside the hollow conductive tube with a first spring and a second spring. The first spring and the second spring are positioned at a first end and a second end of the hollow conductive tube respectively, and the magnet is positioned between the first spring and the second spring. The magnet is configured to move coaxially inside the hollow conductive tube as permitted by the first spring and the second spring, and the magnet suspended inside the hollow conductive tube operates as a tuned mass damper (TMD) to limit a resonant response of the cantilever assembly.

A built-in piezoelectric type online dynamic balance actuator which includes two structurally identical left and right piezoelectric drive adjustment mechanisms at two sides of a housing. The piezoelectric drive adjustment mechanism includes a shaft having one end supported inside a housing chamber by bearing, a middle portion connected to an end cover by bearing, and the other end supported on bearing housing by bearing, a weight mass coupled to the shaft and positioned inside a tightening sleeve with one side connected to the bearing housing and another side connected to the end cover and the housing, and a stator fixedly connected to one side of the end cover, a mover pressed against a surface of the stator through a disk. Through a control center, the mass weights of the left and right piezoelectric drive adjustment mechanisms are fixed to a preset angle. As the main shaft rotates at a high speed, the two weight masses generate centrifugal force which combine to a balance vector to cancel the imbalance vector of the main shaft, improve the mass distribution of the main shaft and better fit the online dynamic balance requirements.

An active damper is disclosed which includes: an elastic support body; a first wall section provided at the elastic support body and defines a first liquid chamber; a second wall section provided on an opposite side and defines a second liquid chamber; a partition wall section which separates the first liquid chamber from the second liquid chamber; an orifice in the partition wall section for communication between the first and second liquid chambers; and a damping unit to attenuate the vibrations transmitted from a vibrating source to the vibration-receiving part. The damping unit includes: a coil to generate a magnetic field according to a current supplied; magnetic members forming a closed magnetic circuit for the magnetic field; and a magneto-viscoelastic elastomer having a viscoelasticity changes depending on the magnetic field. At least one of the first and second wall sections, and the partition wall section has the damping unit.

A method and an apparatus for isolating a vibration of a positioning device are provided. The apparatus includes a base plate for the positioning device, at least one active bearing element for bearing the base plate on/at a foundation and at least one evaluation and control device. The apparatus includes at least one means for determining a foundation movement-dependent quantity, wherein the active bearing element is controllable by the at least one control and evaluation device on the basis of the foundation movement-dependent quantity.

A vibration control element includes a nanovoided polymer layer having a first damping coefficient and a first resonance frequency in a first state and a second damping coefficient and a second resonance frequency in a second state, where the first damping coefficient is different from the second damping coefficient and the first resonance frequency is different from the second resonance frequency.