Described and shown are passive variable stiffness devices, which are of compact design and configured to produce a restoring force that varies optimally with the isolator displacement when subjected to vibration-inducing loading.

A multidirectional adaptive re-centering torsion isolator is used for isolating buildings, tanks and bridges from earthquakes. The multidirectional adaptive re-centering torsion isolator includes a flat and/or articulated slider and four or more cylindrical energy dissipaters. The flat and/or articulated slider positioned on top of the column provides vertical load transmission, low friction and horizontal displacement capacity. The cylindrical energy dissipaters provide displacement, re-centering and damping in any of the horizontal directions.

A solar tracker system includes a torque tube, a solar panel assembly attached to the torque tube, a housing defining a chamber and a fluid passageway extending from the chamber, and an active lock connected to a seal configured to prevent a flow path of fluid while in a sealed state and allow the flow path of fluid in an unsealed state. The system further includes a controller in communication with the torque tube and the active lock. The controller is programmed to receive a command to place the solar panel assembly in a stowed position, instruct the torque tube to rotate the panel assembly to a stowed angle corresponding to the stowed position, monitor a current angle of the panel assembly, compare the current angle to the stowed angle, and instruct the seal to transition to the sealed state when the current angle is equal to the stowed angle.

Solar tracker systems include a torque tube, a column supporting the torque tube, a solar panel attached to the torque tube, and a damper assembly. The damper assembly includes an outer shell surrounding an inner shell. A piston is at least partially positioned within the inner shell and moveable relative thereto. An active lock of the damper assembly includes a housing positioned within the outer shell. The housing defines a cavity and a housing channel extending from the cavity to an outer fluid channel. A shaft extends into the cavity and a valve assembly is attached to the shaft. The shaft is rotatable within the cavity between an unsealed position in which the housing channel is in fluid communication with the cavity, and a sealed position in which the valve assembly is rotationally aligned with the housing channel and obstructs fluid communication between the cavity and the housing channel.

A power strut includes anisotropic damping device that provides different frictional torque on a rotatable member in response to rotation in opposite rotational directions. The anisotropic damping device includes a shell, the rotatable member, and a torsion spring. The shell includes a through hole, and the rotatable member extends through the through hole and is rotatably connected to the shell. The torsion spring is sleeved on the rotatable member and is in interference fit with the rotatable member, and the torsion spring is provided with a first leg fixedly connected to the shell. The rotatable member may include a shaft sleeve fixed to a rotating shaft, with the torsion spring in interference fit with the shaft sleeve.

Solar tracker systems include a torque tube, a column supporting the torque tube, a solar panel attached to the torque tube, and a damper assembly. The damper assembly includes an outer shell surrounding an inner shell. A piston is at least partially positioned within the inner shell and moveable relative thereto. An active lock of the damper assembly includes a housing positioned within the outer shell. The housing defines a cavity and a housing channel extending from the cavity to an outer fluid channel. A shaft extends into the cavity and a valve assembly is attached to the shaft. The shaft is rotatable within the cavity between an unsealed position in which the housing channel is in fluid communication with the cavity, and a sealed position in which the valve assembly is rotationally aligned with the housing channel and obstructs fluid communication between the cavity and the housing channel.

A suspension device includes a damper. The damper includes: a ball screw; a ball screw nut screwed with the ball screw; a bearing that rotatably supports a nut unit (nut assembly) provided with the ball screw nut; and a housing that houses the bearing inside. A part between the housing and the bearing in an axial direction is provided with an elastic body.

A suspension device includes a damper. The damper includes: an outer cylinder; a ball screw housed in the outer cylinder; a fastening member that supports the ball screw inserted therethrough and is attached to an end part of the outer cylinder; and a fixing member that is attached to an end part of the ball screw and fixes the ball screw to the fastening member. An insertion portion, where the ball screw is inserted into the fastening member, is provided with a fitting portion where the ball screw fits the fastening member, and the fitting portion has a spline fitting structure.

A linear actuator comprising a housing with first and second ends, and defining a central cavity extending axially therethrough; a tube having first and second portions, the first portion arranged to slide within the central cavity of the housing, and the second portion extending outwardly from the second end of the housing; a first elongated rotatable screw positioned axially within the central cavity and coaxial with the rube; a first nut mounted about the first elongated rotatable screw and configured to move axially as the first elongated rotatable screw rotates; a second elongated rotatable screw positioned axially within the central cavity; a second nut mounted about the second elongated rotatable screw and configured to move axially within the central cavity as the second elongated rotatable screw rotates; and a spring positioned around the second elongated rotatable screw between the second nut and the second end of the housing.

Described and shown are passive variable stiffness devices, which are of compact design and configured to produce a restoring force that varies optimally with the isolator displacement when subjected to vibration-inducing loading.