Viscoelastic damper assembly applicable both in air and submerged applications and with improved efficiency over prior art solutions for adding damping to an object or structure.

Impact protection for people and goods involved in athletics, transportation, industrial, and military activities comprises a hybrid crush zone shock absorber apparatus, systems, and methods of using the same. More specifically, the present invention reduces forces transmitted to a person or item exposed to impact. Primary applications are in protective articles such as helmets and body padding, surfaces which people or goods may impact, and shock isolation packaging. In addition to reduction in transmitted impact forces, our invention provides clear, irreversible visual indication of the state of readiness of the protective gear to which it is fitted.

A shaft assembly that includes a shaft, which has a wall with an interior surface, a universal joint member, which is coupled to an end of the shaft and a balance weight that is received in the shaft and fixedly coupled to the interior surface. The balance weight includes an ultraviolet light-curable or light-cured resin.

A temperature-independent rotation damper 100 is presented. A housing 108 and a piston 102, between which a viscous liquid is located in annular gaps 118, 120, rotate one around the other. When the temperature falls, the damping by the viscous liquid increases. This effect is countered by reducing the effective area which constitutes the braking action, or by enlarging the volume in the annular gaps 118, 120. As the drive, a material having a positive expansion coefficient is used, which material drives a piston 132. In this way, the damping of the rotation damper 100 is broadly practically independent of the temperature.

A head unit system for controlling an object includes a head unit device that include shear thickening fluid (STF) and a chamber configured to contain the STF. The chamber further includes a gate between a front channel and a back channel. The gate includes a set of bypass openings. The head unit device further includes a piston housed at least partially radially within the chamber. The gate is configured to control flow of the STF between the front channel and the back channel to control contraction of the chamber to provide the controlling of the object.

A cushion-like shaped body (1) having an elastic, gel-like filling (2) in a thin-walled outer layer (3) are frequently used as seals, cushions, vibration dampers or shape compensation materials. This shaped body (1) is to be able to withstand severe strains, distortions, compressions and flexural forces, both in the event of brief severe stress and in the event of prolonged stress. For this purpose, the cushion-like shaped body (1) has a filling (2) of a polyurethane having Shore 000 hardness less than or equal to 80 and a compression set less than or equal to 14%, and this filling (2) is present within a shell having an outer layer (3) of a soft silicone material having a layer thickness of 0.075 to 1 mm and a Shore A hardness between 3A and 45A. Such a shaped body (1) is able to return to its original form without lasting elongation after tensile strain at room temperature up to 250%. There is no formation of cracks, detachment phenomena, bubbles, folds or other lasting damage. The elongation does not cause visible detachment between filling (2) and outer layer (3).

A method for forming a shaft assembly includes: providing a shaft structure, the shaft structure comprising a shaft and a universal joint member that is coupled to an end of the shaft; inserting a weight member to the shaft structure to form an intermediate assembly, the weight member being formed at least partly from a liquid resin, the intermediate assembly having an initial rotational unbalance; rotating the intermediate assembly about a longitudinal axis of the shaft structure to re-distribute a least a portion of the weight member circumferentially about the shaft structure to at least partly attenuate the initial rotational unbalance; and curing the liquid resin while rotating the intermediate assembly to fix the re-distributed portion of the weight member to the shaft structure to thereby form a balance weight that at least partly attenuates the initial rotational unbalance. A shaft assembly is also provided.

Provided is an adjusting method for a resonance frequency of a vibration isolator, the vibration isolator including first to n-th elastic member groups and/or an n+1-th elastic member group, the first to n-th elastic member groups and/or the n+1-th elastic member group being located on an xy plane of an xyz coordinate system, and an xy coordinate system of the xyz coordinate system being a coordinate system obtained by, when a tensor of inertia I with respect to an XYZ coordinate system having an origin in a center of gravity of a vibration sensing side structure or a vibration source side structure is represented as I, rotating an XY coordinate system by =tan.sup.1(2I.sub.XY/(I.sub.XXI.sub.YY)) around a Z axis, the adjusting method including, when rigidity K.sub.i of the first to n-th elastic member groups is represented as

[00001]$\left[K_i\right]=\left[\begin{array}{ccc}{k}_{i.Math.\_.Math.\mathrm{xx}}& 0& 0\\ 0& k_{i.Math.\_.Math.\mathrm{yy}}& 0\\ 0& 0& k_{i.Math.\_.Math.\mathrm{zz}}\end{array}\right],$

rigidity K.sub.n+1 of the n+1-th elastic member group is represented as

[00002]$\left[K_{n+1}\right]=\left[\begin{array}{ccc}{k}_{n+1.Math.\_.Math.\mathrm{xx}}& 0& 0\\ 0& k_{n+1.Math.\_.Math.\mathrm{yy}}& 0\\ 0& 0& k_{n+1.Math.\_.Math.\mathrm{zz}}\end{array}\right],$

A damper (10) includes a housing (11) and a rotor (16) combined with the housing (11) so as to be capable of rotating relative to the housing (11). The damper (10) includes an attenuating medium (90) filled in a rotation area inside the housing (11) wherein the rotor (16) rotates, and added with viscoelasticity by a viscoelasticity treatment; and an enclosure portion (80) provided outside the rotation area of the rotor (16), and communicating with the rotation area.

An isolator configured to isolate a payload from unwanted vibrations and shocks. The isolator includes a housing having a first end and a second end opposite the first end, a primary chamber defined in the housing, a backpressure chamber defined in the housing, a conduit placing the primary chamber in fluid communication with the backpressure chamber, a backpressure membrane in the housing proximate the first end, an elastomer dome in the housing proximate the second end, and a shaft connected to the elastomer dome. The primary chamber and the backpressure chamber are between the backpressure membrane and the elastomer dome. The shaft is configured to be connected to the payload.