A rubber composition for a torsional damper, comprising 10 to 200 parts by weight of carbon black having an iodine adsorption of 100 to 600 mg/g, a DBP oil absorption of 138 to 330 cm.sup.3/.sub.100 g and a nitrogen adsorption specific surface area of 100 to 530 m.sup.2/g, and 5 to 100 parts by weight of a liquid polyolefin oligomer having a number average molecular weight Mn of 3,000 to 4,000, based on 100 parts by weight of at least one of ethylene-propylene-non-conjugated diene terpolymer rubber, ethylene-butene-non-conjugated diene terpolymer rubber and ethylene-propylene copolymer rubber, wherein in the total amount of ethylene and propylene or butene, the content of propylene or butene is 35 to 55 wt. %.

Example embodiments provide mechanical dampers. The mechanical dampers may be applied to dissipate energy in a structure that arises for example from a dynamic load such as seismic activity, vehicle impact, vibration of the structure, wind forces, an explosion, etc. The damper comprises a pair of clamping plates. A shear plate is held between the clamping plates. The shear plate is movable in transverse directions relative to the clamping plates. The damper also comprises a conical wedge coupled between one of the clamping plates and the shear plate. The conical wedge comprises a female conical element and a male conical element that projects into a conical indentation of the female conical element.

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 plastic spring, a pump core, a lotion pump and a press-type packaging container. The plastic spring includes at least one spring unit. Each spring unit includes a first support member, a second support member, and at least two torsion arms. The at least two torsion arms are arranged between the first support member and the second support member, and both ends of each of the torsion arms are respectively connected with the first support member and the second support member. Each of the torsion arms includes at least one vertical section, and an end of each vertical section is connected with the first support member or the second support member.

Devices for superscattering a plate bending wave include a solid plate, and a circular array of spring-mass resonators positioned on a surface of the plate. All resonators in the circular array have a resonance frequency that can be matched to a frequency of a target flexural wave. The circular array has a diameter that can further be matched to the wavelength of the target flexural wave. Scattering efficiencies can exceed several multiples of the theoretical limit.

A bushing includes a cylindrical body and a flange extending from the cylindrical body. The cylindrical body has an inner face defining a bore. The flange includes an outer rim and a face extending radially between the bore and the outer rim. At least one groove is formed in the face. The at least one groove extends from a first end intersecting the bore to a second end adjacent the outer rim such that grease supplied to the bore of the bushing is able to flow through the at least one groove.

The disclosure relates to a torsional vibration damping assembly comprising a deflection mass carder capable of rotation about a rotational axis and deflection masses mounted following one another in a circumferential direction on the deflection mass carrier and deflectable from a basic relative position, wherein the radial position of the deflection masses with respect to the rotational axis changes on deflection from the basic relative position, with each deflection mass being mounted deflectably in both circumferential directions from the basic relative position by coupling formations on the deflection mass carrier, with a resiliently deformable stop formation being provided and assigned to each deflection mass to haft a deflection movement of the deflection mass once a stop deflection has been reached, with the resiliently deformable stop formation comprising a resilient stop material which is fixedly mounted with respect to the deflection mass carder, with the following ratio R being applicable in the assignment to each deflection mass: R=VE/E wherein VE is an effective stop material volume assigned to a deflection mass on reaching the stop deflection by deformation of the resilient stop material and E is an impact metric relative to the kinetic energy of a deflection mass on reaching the stop deflection, and wherein the following applies for the ratio R: 0.15×10−3 m2/ kg R<0.6×10−3 m2/kg.

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.

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.

A bushing includes a cylindrical body and a flange extending from the cylindrical body. The cylindrical body has an inner face defining a bore. The flange includes an outer rim and a face extending radially between the bore and the outer rim. At least one groove is formed in the face. The at least one groove extends from a first end intersecting the bore to a second end adjacent the outer rim such that grease supplied to the bore of the bushing is able to flow through the at least one groove.