Abstract: A magnetorheological material containing a carrier fluid, a particle component and a thixotropic additive to provide stability against particle settling. The thixotropic additive can be a hydrogen-bonding thixotropic agent, a polymer-modified metal oxide, or a mixture thereof. The utilization of a thixotropic additive creates a thixotropic network which is unusually effective at minimizing particle settling in a magnetorheological material.

Abstract: A magnetorheological material containing a particle component and a carrier fluid or mixture of carrier fluids having a change in viscosity per degree temperature (.DELTA..eta./.DELTA.T ratio) less than or equal to about 16.0 centipoise/.degree.C. over the temperature range of about 25.degree. C. to -40.degree. C. The magnetorheological material exhibits a substantial magnetorheological effect and excellent lubricating properties with a minimal variation in mechanical properties with respect to changes in temperature. The magnetorheological material is advantageous in that it provides for the design of devices that are smaller, more efficient and consume less power.

Abstract: A magnetorheological material containing a carrier fluid and a magnetically active particle. The particle has been modified so that the surface of the particle is substantially free of contamination products. The contamination products are removed from the surface of the particle by abrader processing, chemical treatment or a combination thereof. Magnetorheological materials prepared using the particles from which contamination products have been removed exhibit significantly enhanced magnetorheological effects.

Abstract: A semi-active device 20 is provided for damping motion between structures having multi-degrees of freedom. A magnetic field produced by a permanent magnet, a coil, or a combination thereof, change the rheological properties of an MR fluid 40 to effectively lock up the components and the structures to which they are attached to serve as a brake or damper of the associated compound motion. A system 21 employing the MR devices 20 includes a motion detection sensor 15 and a controller 19 to actuate the MR devices 20 when a predetermined motion threshold is exceeded.

Abstract: An electrorheological material comprising a carrier fluid and an atomically, polarizable particle component. The atomically polarizable particle component has a crystalline lattice structure which allows atoms to shift position with respect to each other in response to the application of an electric field. The electrorheological materials are subjected to an alternating current electric field at a frequency of at least 500 Hz. The materials exhibit substantial electrorheological activity over a broad temperature range.

Abstract: A sealless magnetorheological fluid device is disclosed in the form of an engine mount which comprises a baffle plate (58) and a solenoid type coil (40) wrapped within a housing (20). The baffle plate diverts the flow of fluid into a more intimate contact with the coil to influence the characteristics of the fluid. The mount also comprises a first chamber (94), an elastomeric element 90 bonded to an attachment collar (88) and housing (20). An elastomeric bladder (95) is bonded to a lower surface of the housing to define a second chamber (96). Orifices (98) in housing (92) operate with coil (40) to define a valve for controlling the flow of the MR fluid.

Abstract: A magnetorheological material containing a carrier fluid and an iron alloy particle component. The particle component can be either an iron-cobalt alloy or an iron-nickel alloy. The iron-cobalt alloy has an iron:cobalt ratio ranging from about 30:70 to 95:5 while the iron-nickel alloy has an iron:nickel ratio ranging from about 90:10 to 99:1. The iron alloy particle components are capable of imparting high yield stress capability to magnetorheological materials.

Abstract: An electrorheological material containing a carrier fluid and an ionic dye particle component which is an ionically charged compound based on or derived from a conjugated hydrocarbon compound. A preferred ionically charged compound contains at least one aromatic nucleus that has been sulfonated and/or carboxylated to form a negatively charged system which has, in turn, been offset with a positive ion. The electrorheological material is useful for creating aesthetic visual effects and responds quickly to an electric field.

Abstract: An electrorheological material comprising a carrier fluid and an atomically polarizable particle component. The atomically polarizable particle component has a crystalline lattice structure which allows atoms to shift position with respect to each other in response to the application of an electric field. The electrorheological materials are subjected to an alternating current electric field at a frequency of at least 500 Hz. The materials exhibit substantial electrorheological activity over a broad temperature range.

Abstract: This invention relates to sealless designs of magnetorheological fluid dampers. With these sealless designs a piston rod extends above and below a piston head within a cylindrical housing and has frustoconical elastomer elements attached to and between the rod and housing to allow translation of the piston head and rod. The piston head has a coil contained radially therein that produces magnetic flux in and around the piston. The advantages of utilizing an MR fluid according to the invention include magnetic fields which are easily produced by low voltage electromagnetic coils, damping effects which are velocity independent, and higher yield strength obtained by the MR fluid capable of generating greater damping forces.

Abstract: Magnetorheological (MR) fluid dampers are optimized. Dimensional relationships involved in the flow of magnetic flux are related to an operational parametric ratio of magnetic flux density in the fluid to the flux density in the steel. A magnetic valve is utilized to change the flow parameters of the MR fluid and, hence, the operational characteristics of the damper. Several embodiments depicting improved piston designs, including spool as well as toroidal configurations, are disclosed. In addition, both single and twin-tube housing designs are presented.

Abstract: An electrophoretic fluid torque transmission apparatus in which cooperable electrodes are connected respectively to drive and driven elements. An electrophoretic fluid capable of separating into particle-rich and particle-deficient phases by electrophoresis operates in surface contact with the electrodes. An electrically non-conductive material having raised surface areas and spaces between the surface areas is associated with one or more of the electrodes. When a voltage is applied between the electrodes in a first direction, the particle-rich phase of the fluid collects on one of the electrodes and also makes contact with the spaces and the raised surface areas of the material associated with the other electrode thereby engaging or locking the electrodes together and transmitting force between the elements.

Abstract: A transparent electrorheological fluid having a fluid component, a particle component, and an activator wherein the index of refraction mismatch between the fluid component and the particle component is less than about 0.02 and wherein the conductivity of the particle component is at least about three times greater than the conductivity of the fluid component and is in the range of from about 1.times.10.sup.-5 s/m to about 1.times.10.sup.-9 s/m.

Abstract: An apparatus and method for control of stiffness and damping in a flexible composite structure by the application of an electric field to an electrophoretic fluid forming part of the structure. The structure includes spaced, parallel, flexible layers of material which include confronting electrodes. The electrophoretic fluid is capable of separating into particle-rich and particle-deficient phases by electrophoresis and operates in surface contact with the layers. An electrically nonconductive material having raised surface areas and spaces between the surface areas is associated with one or more of the layers. When a voltage is applied between the layers in a first direction, the particle-rich phase of the fluid collects on one of the layers and also makes contact with the spaces and the raised surface areas of the material associated with the other layer thereby engaging or locking the layers together to increase the shear strength of the layers and thus the complex stiffness of the structure.

Abstract: An electrophoretic fluid torque transmission apparatus and method in which cooperable electrodes are connected respectively to drive and driven elements. An electrophoretic fluid capable of separating into particle-rich and particle-deficient phases by electrophoresis operates in surface contact with the electrodes. An electrically non-conductive material having raised surface areas and spaces between the surface areas is associated with one or more of the electrodes. When a voltage is applied between the electrodes in a first direction, the particle-rich phase of the fluid collects on one of the electrodes and also makes contact with the spaces and the raised surface areas of the material associated with the other electrode thereby engaging or locking the electrodes together and transmitting force between the elements.

Abstract: An electrorheological material containing a carrier fluid, an anionic surfactant particle component, and an activator. The non-abrasive anionic surfactant acts as both a particle component and a surfactant and the electrorheological material is miscible with water and will not mar the surface of objects utilized in an electrorheological device.

Abstract: An electrophoretic fluid damper in which cooperable electrodes are slidably disposed one within the other and are connected respectively to relatively movable members. An electrophoretic fluid capable of separating into particle-rich and particle-deficient phases by electrophoresis operates in surface contact with the electrodes. An electrically nonconductive material having raised surface areas and spaces between the surface areas is associated with one of the electrodes. When a voltage is applied between the electrodes in a first direction, the particle-rich phase of the fluid collects on one of the electrodes and also makes contact with the spaces and the raised surface areas of the material associated with the other electrode thereby engaging or locking the electrodes together and transmitting force between the members.

Abstract: An apparatus for controlling the transmission of torque between drive elements using an electroactive fluid which is sealed within an enclosed chamber. A housing defines the chamber and includes at least one end defining an opening. Spaced electrodes are provided in the chamber in contact with the fluid and are respectively connected to the drive elements. A controllable power source applies a variable electric field to the fluid such that force is transmitted between the electrodes by the fluid according to the strength of the field. A shaft connects one of the electrodes to one of the elements and extends through the opening. A ferrofluid seal assembly prevents leakage of the fluid from the chamber through the opening. The assembly defines with the shaft an annular space in communication with the fluid. A magnetic circuit is provided in the assembly by a permanent magnet for applying a concentrated magnetic field in one or more regions across the annular space.

Abstract: Controllable electrorheological fluid composite structure elements incorporate electrorheological fluids as a structural component between opposing fluid containment layers to form at least a portion of any variety of extended mechanical systems such as plates, panels, beams and bars or structures including these elements. The electrorheological fluid is operatively contained in a region between the containment layers and has complex shear and tensile modulus properties which vary with the electric field applied thereto. A variable power source is utilized to create an electric potential between the layers of the structure element to create the electric field. An alternative power source may include the use of a piezoelectric material layer. In order to maintain the insulation and spacing between the containment layers, a fabric or separating layer having an open mesh is provided which permits the transportation of electrorheological fluid in the region between the layers.

Abstract: An electrorheological fluid torque transmission and conversion system provides for variable control of torque in clutch and brake applications. Communication of mechanical energy between the drive elements is accomplished by magnetic coupling to eliminate the need for a dynamic fluid seal for interface of moving parts to the interior portion of the electrorheological fluid containment chamber. Permanent magnets are associated respectively with each of a first member and a second member which are magnetically coupled through a surface with low magnetic permeability such that the first member and second members rotate in unison. A variety of permanent arrangements may be utilized. Further, the drive element internal to the electrorheological fluid chamber may be both mechanically and electrically decoupled. A floating electrode may be capacitively coupled through the fluid to the power supply. Also provided are inner and outer conductive plates are provided for increased fluid surface contact area.