A shock absorber includes a first passage provided in a piston and through which a working fluid moves from a chamber on an upstream side to a chamber on a downstream side in a cylinder due to movement of the piston, a first damping force generation mechanism provided in the first passage to generate a damping force, a second passage (141) provided in a piston rod (21), and a fixing member fixed to the piston rod (21) to form the second passage (141), and a second damping force generation mechanism provided in the second passage (141) to generate a damping force, in which a throttle member (161) provided in the second damping force generation mechanism, including a plurality of notch parts (171) at substantially regular intervals in a circumferential direction to form a throttle flow path (76) in the second passage due to the notch parts (171), and formed to have a flow path area of the throttle flow path (76) that is constant regardless of an attachment position thereof in the circumferential direction is further provided.

An active inertial damper system (100) and method for damping vibrations (V1,V2) in a structure (11). An inertial mass (2) is supported by a support frame (1) via spring means (3) to form a mass-spring system (2,3) having a resonance frequency (fn). A controller (6) is configured to control a force actuator (4) to adapt the driving force (Fd) as a function of measured vibrations (V1,V2). The controller (6) comprises a filter (H) determining a magnitude (M) of the driving force (Fd) as a function of frequency (f) for the measured vibrations (V1,V2) in the structure (11). The filter (H) is configured to provide an anti-resonance dip in the magnitude (M) of the driving force (Fd) at the resonance frequency (fn) of the mass-spring system (2,3) to suppress resonant behaviour of the mass-spring system (2,3) itself.

A damper unit for use in a vibration-reducing assembly for a steering wheel is disclosed. An elastomeric damper element is molded on an inner sleeve and includes a plurality of elastomeric ribs forming a radially outer engagement surface, and a plurality of elastomeric support studs, which are mutually spaced in a circumferential direction are flexible in all directions transverse to said axis. Methods for making a damper unit and a damper assembly are also disclosed.

Various implementations include a device for controlling vibration with piecewise-linear nonlinearity. The device includes a stiffness element, a mass, a stopper, and an actuator. The stiffness element is expandable and compressible along an axis. The mass is coupled to the stiffness element. The mass has a resting mass position along the axis. The actuator is coupled to the stopper. The actuator is configured to move the stopper along the axis to vary a gap size. The gap size is measured as a distance between the resting mass position and a resting stopper position.

The present disclosure discloses a Stewart vibration isolation platform with Macro Fiber Composite (MFC) plates. The vibration isolation platform includes: an upper load platform, a lower foundation platform, a controller, and a plurality of single-leg vibration isolation unit groups arranged between the upper load platform and the lower foundation platform. Each of the single-leg vibration isolation unit groups includes two single-leg vibration isolation units. The single-leg vibration isolation unit includes a first diaphragm spring and a second diaphragm spring. An MFC actuator and an MFC sensor are respectively arranged on two sides of the first diaphragm spring and the second diaphragm spring. The MFC actuators and the MFC sensors are all connected to the controller.

A method for determining, measuring and/or monitoring properties of a sensor system. In the method, a controlled change of at least one system parameter of the sensor system takes place in such a way that prior to the controlled change, the system parameter includes a first value and assumes at least one further value as a result of the controlled change. At least one characteristic variable of the sensor system and/or a change of the at least one characteristic variable of the sensor system is/are determined for the at least one further value of the system parameter. The determination, measuring and/or monitoring of properties of the sensor system take place based the at least one further value of the system parameter and the at least one characteristic variable determined in the second step and/or the change of the at least one characteristic variable.

Disclosed herein are hydraulic actuators and methods for the operation of actuators having variable relative pressure ratios. Further disclosed are methods for designing and/or operating a hydraulic actuator such that the actuator exhibits a variable relative pressure ratio. In certain embodiments, the relative pressure ratio of the hydraulic actuator may be dependent on one or more characteristics (such as, for example, frequency or rate of change) of an oscillating input to the hydraulic actuator.

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 variable stiffness spring assembly includes first and second members made of a first material and separated by a gap along at least a portion of their lengths, and one or more layers made of a second material disposed in the gap. The variable stiffness spring assembly can be incorporated into or take the form of a limb support assembly, such as a prosthetic foot. The second material disposed between the first and second members is rate-sensitive or speed-dependent, such that the material exhibits different properties when the user of the prosthetic foot is walking at high or fast walking speeds compared to low or slow walking speeds. The prosthetic foot can exhibit high damping and energy absorption, and therefore stability, at slow speeds, and high energy return at faster speeds.

A tilger for a rotating body includes an annular body movably coupled to a rotatable portion of the rotating body. The tilger includes a spring interposed between the first annular body and the rotatable portion. Rotation of the rotatable portion relative to the annular body is to compress and decompress the spring. The tilger includes a ring positioned on an outer surface of the annular body and configured to expand as a rotational speed of the ring increases to decrease a total inertia of the annular body and the ring applied to the spring.