40results about How to "Enhance the magnetorheological effect" patented technology

The invention relates to the field of intelligent magnetic materials and in particular relates to a graphene @Fe3O4 compound water base magnetorheological fluid and a preparation method thereof, solving the problems that existing magnetorheological fluids are easy to settle and the stability and magnetorheological effects of the magnetorheological fluids are difficult to optimize at the same time. The preparation method comprises the following steps: preparing a Fe3O4 water base magnetic fluid with FeCl2.4H2O and FeCl3.6H2O; sequentially adding concentrated sulfuric acid, potassium permanganate and hydrogen peroxide to natural flake graphite and sodium nitrate to prepare graphite oxide; and then carrying out ultrasonic dispersion on home-made graphite oxide to prepare graphene oxide, finally adding a surfactant, the Fe3O4 water base magnetic fluid and a reducing agent to graphene oxide, washing the solution with deionized water until the solution is neutral, and then dispersing graphene @Fe3O4 compound magnetic particles in the deionized water to undergo ultrasonic dispersion, removing the precipitates and taking the supernatant, namely the stable graphene @Fe3O4 compound water base magnetorheological fluid, wherein the magnetic particles are graphene @Fe3O4 and account for 5-35wt% of the whole. The method has the advantages of good stability, low zero field viscosity, high shear strain and wide operating temperature range.

The magnetic rheologic liquid is composed of components: chelation type surfactant / carbonyl iron hull type magnetic compound particles, and silicone oil based compound assorted carrier liquid prepared from silicone oil and additive. The additive includes thixotropic agent, antioxidant, antiwear additive, and surfactant. The method for preparing the liquid includes steps: mixing round surfactant being added to silicone oil; next, adding antioxidant, thixotropic agent, and antiwear agent, then mixing them to obtain silicone oil based compound assorted carrier liquid; adding magnetic compound particles to the carrier liquid, and after procedures of mixing, ballmilling, and separating out friction balls, then sealing the liquid inside plastic bottle; stable silicone oil based magnetic rheologic liquid is obtained after series of procedure: placing the plastic bottle in magnetic field, taking out the liquid, and mixing etc. The liquid is applicable to damper, variator for cars etc.

The invention relates to a double-access foam metal magneto-rheological fluid damper, wherein magneto-rheological fluid foam metal is fully filled in the inner wall of a working cylinder; front and rear end covers are respectively fixed at two ends of the working cylinder; a piston is connected in the working cylinder in a matching manner; piston rods at two ends of the piston respectively extend out of the front end cover and the rear end cover; an excitation coil is wound between two shaft shoulders of the piston; the excitation coil is connected with an external control power supply through an electrification conductor wire passing through a central hole in the middle of one end of the piston; and the external control power supply is used for electrifying the excitation coil. According to the invention, by storing magneto-rheological fluid through foam metal, compared with the traditional magneto-rheological fluid damper, a sealing structure is not required; the structure is simple; furthermore, the amount of required magneto-rheological fluid is greatly reduced; the cost is greatly reduced; furthermore, abrasion of the traditional damper in a sealing clearance can also be reduced; the service life is prolonged; simultaneously, compared with porous sponge, foam metal has the great advantages of being high in intensity, abrasive resistant, adjustable in magnetic conductivity and the like; and an obvious magneto-rheological effect can also be generated; therefore, the double-access foam metal magneto-rheological fluid damper has good application prospect.

The invention provides a preparation method of magnetorheological elastomer with high heat resistance and good tensile property, comprising the steps of a, mixing well modified carbonyl iron powder, asilane coupling agent, and methyl vinyl silicone rubber; covering the surface of the carbonyl iron powder with a polymer layer composed of methyl vinyl silicone rubber and a silane coupling agent, adding ethylene propylene diene monomer rubber, a plasticizer and reinforcing particles, and mixing well to obtain mixed rubber; b, adding the mixed rubber in an open mill, adding an antiaging agent anda vulcanizing agent, performing open milling and rubber covering, injecting the obtained material into a mold, performing pre-structural treatment under a magnetic field, and vulcanizing on a plate vulcanizing press so as to obtain the magnetorheological elastomer with high heat resistance and good tensile property. The preparation method herein overcomes the technical difficulty in the preparation of magnetorheological elastomer by ethylene propylene diene monomer rubber, and excellent properties of the magnetorheological elastomer can be exerted.

Disclosed is a method and electromagnetic device for manufacturing an anisotropic magneto-rheological elastomer (MRE) with an improved magneto-rheological effect. The electromagnetic device includes upper and lower electromagnets, and a test piece located therebetween. The upper and lower electromagnets are configured to apply a magnetic field of variable strength, which may be controlled by current applied from a power controller, to the test piece in a desired direction or orientation. More specifically, the device is designed in such a manner that carbonyl iron powder (CIP) (magnetic-responsive particles) dispersed in a magneto-rheological elastomer using natural rubber as a matrix can be oriented in the application direction of the magnetic field. A MRE produced by the method and electromagnetic device of the invention prevents formation of bubbles within a test piece, thereby improving the arrangement / orientation of CIP with the matrix.

The invention relates to an universal gripper using a magneto-rheological plastic body. The universal gripper comprises a U-shaped supporting frame, a coil, a partitioning plate and a partitioning layer, wherein the coil is wound at the middle part of the supporting frame; the partitioning plate is arranged at the middle part of the supporting frame; the partitioning layer is formed among the partitioning plate, the coil and the U-shaped supporting frame; a charging battery and a current control circuit are placed in the partitioning layer; a rubber jacket is tightly coated outside; the high-performance magneto-rheological plastic body is filled between the U-shaped bracket and the rubber jacket. The universal gripper has the advantages that the gripping force can be adjusted; the shape of the gripper can be changed to enable the gripper to be better attached to the surface of an object; in addition, the whole structure is simple and the manufacturing cost is lower.

The invention discloses a phase change type magnetorheological material and a preparation method thereof. The phase change type magnetorheological material comprises the following materials in part by mass: 38.2-69.1 parts of base materials, 30-60 parts of magnetic particles and 0.9-1.8 parts of surfactant. The base materials comprise paraffin wax and albolene, and the mass ratio of the paraffin wax to the albolene is 1.5:1-1:1.5. The magnetic particles are carbonyl iron powder. The phase change type magnetorheological material has a high magneto-induced effect and high stability, has the physical property of non-solvent type magnetorheological elastomer at room temperature, is converted into a fluid state from a viscoplastic state at high temperature (about 50 DEG C) due to the phase change performance of the base materials, and has typical characteristics of magnetorheogical fluid, namely, the phase change type magnetorheological material can be freely converted from magnetorheogical fluid to magnetorheogical elastomer or from the magnetorheogical elastomer to the magnetorheogical fluid along temperature change.

The invention discloses an application of an ionic liquid serving as a magnetorheological fluid base solution, and also discloses magnetorheological fluid based on the ionic liquid, namely an ionic liquid-based magnetorheological fluid. The magnetorheological fluid comprises the base solution, a dispersed phase and addictives, wherein micro or submicro magnetic particles are used as the dispersed phase; the base solution is an ionic liquid and comprises the components in parts by weight: 8-39.5 parts of the base solution, 60-90 parts of the dispersed phase and 0.5-5 parts of the addictives. A method for preparing the magnetorheological fluid based on the ionic liquid comprises the following steps of: firstly, preparing magnetic particles; acquiring the ionic liquid and the maddictives in the mass proportion; adding the addictives into the ionic liquid, and stirring for dissolving in a mixed mode; finally, adding the magnetic particles, stirring and uniformly stirring in a mixed mode to finish the preparation of the magnetorheological fluid. The magnetorheological fluid is high in stability, wide in operating temperature and high in designability, has environment-friendly property, and is suitable for vacuum environment.

The invention belongs to the field of bridge vibration control in civil engineering, and particularly relates to a laminated magneto-rheological high damping elastomer single core support. The supportcomprises an upper steel disc, a lower steel disc, a laminated supporting mechanism and a lead core arranged at the upper steel plate, and an excitation mechanism arranged at the lower steel disc. The laminated supporting mechanism is cylindrical, and a round hole used for the lead core to penetrate is formed in the center of the laminated supporting mechanism. The laminated supporting mechanismis formed alternate vulcanization of the magneto-rheological elastomer and a steel plate. The excitation mechanism comprises an excitation coil, a reeling bracket and an iron core. The excitation coilis wound to the iron core by the reeling bracket. A round hole is formed in the middle of the iron core, and is used for positioning the lead core. The the lead core is fixed to the middle of the laminated supporting mechanism and the iron core, and therefore the positioning accuracy of the whole structure is guaranteed, and firmness of connection is improved. When shearing deformation of the support occurs, shearing deformation of the whole lead core occurs forced by the laminated supporting mechanism and the iron core, and therefore energy dissipation is achieved, and damping and rigidity of the support is improved overall.

The invention discloses a semi-active type high-static and low-dynamic vibration isolator with a magnetorheological elastomer. The semi-active type high-static and low-dynamic vibration isolator withthe magnetorheological elastomer comprises a base, a control system, a direct current adjustable power source and the magnetorheological elastomer. The base is of a cylinder-shaped steel structure, aweight sensor is mounted at the center position of the bottom of the base, a cylindrical iron core is arranged at the center position of the interior of the base, the magnetorheological elastomer is fixedly arranged in an annular groove of the iron core, and the iron core below the magnetorheological elastomer is wound with a coil. The two ends of the coil are connected with the current output endof the direct current adjustable power source through wires, and the control signal output end of the control system is connected with the signal input end of the direct current adjustable power source through wires. A buckling circular plate is mounted at the top of the magnetorheological elastomer, a platform is mounted at the top of the buckling circular plate, and the platform, the buckling circular plate and the magnetorheological elastomer are fixedly connected through bolts. The semi-active type high-static and low-dynamic vibration isolator with the magnetorheological elastomer has agood low-frequency vibration isolation effect and a simple and reliable structure, and can trace the changing of the loading weight, and the control method is simple.

The invention discloses a side-inclining preventing vehicle driving transverse stabilizer bar arranged on a vehicle suspension. The side-inclining preventing vehicle driving transverse stabilizer bar is characterized in that a magneto-rheological rotation damper is fixedly connected to the middle of a transverse stabilizer bar body so that the transverse stabilizer bar body can be divided into a left half torsion bar and a right half torsion bar; the magneto-rheological rotation damper comprises a magneto-rheological rotation damper stator, a magneto-rheological rotation damper rotor, an electromagnetic coil and a shell end cover; the left half torsion bar is used for driving the magneto-rheological rotation damper stator to rotate or the right half torsion bar is used for driving the magneto-rheological rotation damper rotor to rotate through the shell end cover so that the electromagnetic coil is powered on to enable reverse damping force to be produced in the magneto-rheological rotation damper while the magneto-rheological rotation damper stator and the magneto-rheological rotation damper rotor move relatively, and therefore a side-inclining preventing structure is formed. The side-inclining preventing vehicle driving transverse stabilizer bar can reduce the vehicle inclining degree when a vehicle swerves, and therefore the comfort, stability and safety of the vehicle are improved.

The invention discloses a complex curved surface component forming device and method on the basis of magnetorheological elastomers. The device comprises magnetic field generation device pole heads, aforming mold, pressure heads, the magnetorheological elastomers, a pipe blank and high-pressure liquid input channels. Through holes are axially and radially formed in the magnetorheological elastomers, the magnetorheological elastomers are arranged inside the pipe blank, the magnetorheological elastomers are attached to the inner wall of the pipe blank (6), the pipe blank is arranged in the forming mold, the two pressure heads are arranged at the two ends of each magnetorheological elastomer in a close pressing manner respectively, the high-pressure liquid input channels are formed in the twopressure heads, and the high-pressure liquid input channels align with and communicate with the radial through holes in the magnetorheological elastomers. The magnetorheological elastomers can be improved in magnetorheological effect because of the high content of magnetic particles, the modulus of the magnetorheological elastomers is increased, the deformation of a pipe is increased, and then the problems that a thin-wall component with a large reducing ratio and big section changes is difficult to control in formation, high in distributional difference of wall thickness, low in dimensionalaccuracy and the like are effectively solved.

The invention discloses an arc type magneto-rheology and friction transmission device for electromagnetic thermal memory alloy extrusion. A driving shaft, a driven shaft, a left end cover, an outer round barrel and a right end cover are included; the portion, located in a shell, of the driving shaft forms a transmission segment; armatures are arranged between the two ends of the transmission segment and the left end cover and the right end cover; the positions among the armatures, the transmission segment and the inner wall of the shell are filled with magneto-rheological liquid; the armaturesare provided with a plurality of guiding rods, and the guiding rods are sleeved with first shape memory alloy springs; the circumferential face of the transmission segment is provided with grooves, and push rods are arranged in the grooves; second shape memory alloy springs are further arranged in the grooves; an inner friction block is fixed to the outer end of each push rod, and an outer friction ring is arranged on the side wall of the shell; and a magnetic excitation coil is embedded in the inner wall of the shell. The arc type magneto-rheology and friction transmission device for electromagnetic thermal memory alloy extrusion can effectively improve the efficiency for the whole transmission device to transmit the torque, and guarantees the stability of the torque transmitted by the whole transmission device; and meanwhile, the cost of the whole transmission device can be lowered.

The invention discloses magnetorheological gel and a preparation method thereof. The magnetorheological gel comprises magnetic particles, a carrier liquid and a polar solvent or a magnetic fluid whichis incompatible with the carrier liquid; and the magnetorheological gel is composed of the following components in percentages by volume: 10-40% of the magnetic particles, 60-90% of the carrier liquid, and 0.1-10% of the polar solvent or the magnetic fluid. The magnetorheological gel disclosed by the invention has excellent sedimentation stability and a remarkable magnetorheological effect; and the preparation method is simple and has low costs.

The invention discloses a temperature-controlled circular variable wedge-shaped magnetorheological fluid clutch. The temperature-controlled circular variable wedge-shaped magnetorheological fluid clutch comprises a driving shaft, a clutch shell, a driven shaft, a magnet exciting coil and a magnetorheological fluid; a coil groove is formed in the outer side of the clutch shell; the magnet excitingcoil is mounted in the coil groove; a plurality of isolating baffle plates are arranged around a circle of the outer side of a transmission section; a first returning spring is arranged on the outer side of each isolating baffle plate; the gap among the isolating baffle plates and the inner wall of an outer shell are filled with the magnetorheological fluid; a centrifugal plate is arranged on theinner side of each isolating baffle plate; a filtering hole is also formed in each isolating baffle plate; a filtering film is mounted in the filtering hole; two electric brush sliding rings are alsoarranged on the driving shaft in a sleeving manner; one end of the magnet exciting coil is connected with one electric brush sliding ring after passing through a shape memory alloy temperature controlswitch; and the other end is directly connected with the other electric brush sliding ring. According to the temperature-controlled circular variable wedge-shaped magnetorheological fluid clutch, themaximum value of the torque which can be transferred is greater; the transferring efficiency is higher; the energy consumption is lower; and the stability of a transmission process can be ensured.

The invention discloses a magneto-rheological transmission device extruding bearing bushes based on coil heating induced shape memory alloys. The magneto-rheological transmission device comprises a driving shaft, a driven shell and a driven shaft, a coil groove is formed in the middle of a transmission section, and a magnet exciting coil is arranged in the coil groove. A plurality of bearing bushes are arranged on the two sides of an outer flow guide disc correspondingly, a containing groove is formed in the position, on the transmission section, of each bearing bush, and ejector blocks andshape memory alloy springs are arranged in the containing grooves. A first liquid guide channel is arranged between the coil groove and each containing groove, and second liquid guide channels are arranged on the inner sides of the coil groove and the containing grooves. The containing grooves, a coil containing cavity, the first liquid guide channels, the second liquid guide channels, third liquid guide channels and fourth liquid guide channels are filled with liquid gallium-based alloys. According to the magneto-rheological transmission device extruding the bearing bushes based on the coil heating induced shape memory alloys, the influence of coil heating on the performance of the magneto-rheological transmission device is reduced, the transmission performance of the transmission device under the high-temperature working condition is enhanced, and therefore the reliability and stability of the transmission device are improved.

The invention discloses a preparation method of a highly magneto-rheological silicone rubber-based magneto-rheological elastomer and belongs to the field of magneto-rheological materials. The preparation method comprises the following steps: dissolving ferric citrate and ferric nitride in water; compounding and drying with graphite oxide and calcining the same; then compounding and ball-milling with carboxyl ferric powder and mixing with liquid silicone rubber; shearing and ultrasonically treating the mixture to prepare conductive liquid silicone rubber; then electrifying the silicone rubber to generate a magnetic field; distributing the carboxyl ferric powder and ferric oxide powder complying with the magnetic field; and finally, leaving the mixture to stand and cure to obtain a highly rheological elastomer. According to the highly magneto-rheological silicone rubber-based magneto-rheological elastomer prepared by the preparation method disclosed by the invention, the magneto-rheological effect is enhanced greatly by improving distribution of inner magnetic particles, and the tensile strength and the rebound resilience of silicone rubber are enhanced greatly by preparing the uniformly distributed silicone rubber-based magneto-rheological elastomer. The preparation process is safe and green and free of pollution.

The invention aims to provide a step-shaped magnetorheological damper. The step-shaped magnetorheological damper comprises a working cylinder, a piston rod, a piston body of an electromagnetic piston,magnetorheological fluid, a permanent magnet positioning ring, a permanent magnet ring and a coil, wherein the piston body is in a step shaft shape. The step-shaped magnetorheological damper can solve the problems of small damping force and the like in the prior art, meanwhile, the volume of the magnetorheological fluid for working is reduced, the magnetorheological damping force is greatly improved, and the step-shaped magnetorheological damper has the advantages that the required magnetorheological fluid dosage is small, and the magnetorheological effect is remarkable.

The invention discloses a magneto-rheological elastomer capable of accurately controlling axial distribution of magnetic particles and a preparation method thereof. The method comprises the steps that: firstly, according to the magneto-rheological effect change requirement of a target magneto-rheological elastomer in a certain axial direction, the target magneto-rheological elastomer is divided into a plurality of sections of magneto-rheological effect monomers according to a certain division sequence, the magneto-rheological effect monomers are prefabricated, and each section of the magneto-rheological effect monomers has the mass fraction occupied by a specific magnetic particle; and stacking the prefabricated magneto-rheological effect monomers in a final shaping mold consistent with the three-dimensional model in shape in sequence, and heating, pressurizing and forming the combined body to obtain the target magneto-rheological elastomer. According to the magneto-rheological elastomer prepared by the invention, the content of the magnetic particles in each magneto-rheological effect monomer is accurately controlled, so that the magneto-rheological effect generated by the magneto-rheological effect monomer generates gradient distribution in the axial direction, and the requirement of serving as a medium for forming a complex curved surface metal component by pressure is met.

The invention aims to provide a series extrusion type magnetorheological damper. The series extrusion type magnetorheological damper comprises a working cylinder, a piston rod, a piston body of an electromagnetic piston, magnetorheological fluid, a permanent magnet positioning ring, a permanent magnet ring and a coil, wherein a plurality of annular grooves are formed in the left end surface and the right end surface of the piston body at intervals in the radial direction. According to the series extrusion type magnetorheological damper, the problems that existing damping force is small and thelike can be solved, meanwhile, the volume of the magnetorheological fluid for working is reduced, the magnetorheological damping force is greatly improved, and the series extrusion type magnetorheological damper has the advantages that the required magnetorheological fluid is small in dosage and the magnetorheological effect is remarkable.

The invention discloses a novel sealing device for a large-mining-height hydraulic support stand column cylinder opening. The novel sealing device comprises an outer cylinder body, a middle cylinder body and a piston rod. The middle cylinder body is assembled in the outer cylinder body in a sliding manner, and the piston rod is assembled in the middle cylinder body in a sliding manner. A first upper sealing assembly is arranged at the upper portion of the inner wall of the outer cylinder body, a second upper sealing assembly is arranged at the upper portion of the inner wall of the middle cylinder body, and the first upper sealing assembly and the second upper sealing assembly are of the same structure. The first upper sealing assembly comprises a guide sleeve and a blocking sleeve, wherein the guide sleeve is located below the blocking sleeve. A wide-ring-shaped groove is formed in the outer wall of the guide sleeve, an electromagnet is assembled in the wide-ring-shaped groove, and the electromagnet is connected with an external power source. A sealing groove is formed in the inner wall of the guide sleeve, and a Y-shaped sealing ring, a second O-shaped sealing ring and a third blocking ring are embedded in the sealing groove. The Y-shaped sealing ring is made of polyurethane base magnetic current elastomers, and the second O-shaped sealing ring is made of nitrile rubber basemagnetic current elastomers. By means of the novel sealing device, the elastic modulus and rigidity of the two kinds of sealing rings can be changed, the system sealing performance is improved, and the effective support performance of a work face is improved.

The magnetic rheologic liquid is composed of components: chelation type surfactant / carbonyl iron hull type magnetic compound particles, and silicone oil based compound assorted carrier liquid prepared from silicone oil and additive. The additive includes thixotropic agent, antioxidant, antiwear additive, and surfactant. The method for preparing the liquid includes steps: mixing round surfactant being added to silicone oil; next, adding antioxidant, thixotropic agent, and antiwear agent, then mixing them to obtain silicone oil based compound assorted carrier liquid; adding magnetic compound particles to the carrier liquid, and after procedures of mixing, ballmilling, and separating out friction balls, then sealing the liquid inside plastic bottle; stable silicone oil based magnetic rheologic liquid is obtained after series of procedure: placing the plastic bottle in magnetic field, taking out the liquid, and mixing etc. The liquid is applicable to damper, variator for cars etc.

The invention aims to provide an embedded extrusion type magnetorheological shock absorber which comprises a working cylinder, a piston rod, a piston body, magnetorheological fluid, permanent magnet positioning rings, permanent magnet rings I and permanent magnet rings II, wherein the left end face and right end face of the piston body are provided with an annular convex portion respectively. By adopting the embedded extrusion type magnetorheological shock absorber provided by the invention, the existing problems such as relatively small damping force and the like can be solved, simultaneously, the volume of the magnetorheological fluid for work is reduced, and the magnetorheological damping force is greatly improved. The magnetorheological shock absorber has the advantages of less required amount of the magnetorheological fluid and significant magnetorheological effect.

The invention relates to suspended particles for water-based magnetorheological fluids and a manufacturing method thereof. The magnetic particle wrapped by hydrophilic polymer, the surface of the magnetic metal is coated with an inorganic oxide layer, which is characterized in that: the inorganic oxide layer is coated with a hydrophilic polymer layer with an alkoxy silicon at the end. Its preparation method, according to the ratio of substances, 100 parts of magnetic metal composite particles coated with inorganic oxides on the surface, 0.1 to 5.0 parts of alkoxy metal compound, and a hydrophilic polymer with an alkoxy silicon at the end 0.05 to 5.0 parts are fully dispersed in 50-10000 parts of N,N-dimethylformamide solvent, while stirring, add lye dropwise to adjust the pH value of the system, use magnetic separation and water washing to purify and collect the solid, and dry After obtaining the product. The invention has good oxidation resistance and excellent soft magnetic properties, and its preparation method is convenient and easy.

The invention discloses a preparation method of a magnetorheological elastomer for controlling the radial distribution of magnetic particles. The preparation method comprises the following steps: (1)mixing the magnetic particles with auxiliary agents uniformly, adding the obtained mixture to a fluid-state rubber material, and performing stirring through a high speed mixer so as to achieve uniformdistribution of the magnetic particles in the rubber matrix; (2) stirring the mixture evenly, putting the mixture in a vacuum container, and performing vacuuming so as to remove air bubbles inside the mixture; and (3) pouring the mixture obtained in the step (2) into a cylindrical mold, sealing the mold, putting the sealed mold horizontally so as to make the mold rotate along the horizontal axisand achieve curing and rotation of the mixture at the same time, and adjusting the rotation speed of the mold and the change rule of the rotation speed so as to control the radial distribution of themagnetic particles in the rubber matrix. The method which is capable of achieving the distribution of the magnetic particles in the rubber matrix through control on the rotation speed of the mold hassimple operation, easy implementation and greatly-reduced cost.

The invention discloses a magneto-rheological elastomer capable of accurately controlling axial distribution of magnetic particles and a preparation method thereof. The method comprises the steps that: firstly, according to the magneto-rheological effect change requirement of a target magneto-rheological elastomer in a certain axial direction, the target magneto-rheological elastomer is divided into a plurality of sections of magneto-rheological effect monomers according to a certain division sequence, the magneto-rheological effect monomers are prefabricated, and each section of the magneto-rheological effect monomers has the mass fraction occupied by a specific magnetic particle; and stacking the prefabricated magneto-rheological effect monomers in a final shaping mold consistent with the three-dimensional model in shape in sequence, and heating, pressurizing and forming the combined body to obtain the target magneto-rheological elastomer. According to the magneto-rheological elastomer prepared by the invention, the content of the magnetic particles in each magneto-rheological effect monomer is accurately controlled, so that the magneto-rheological effect generated by the magneto-rheological effect monomer generates gradient distribution in the axial direction, and the requirement of serving as a medium for forming a complex curved surface metal component by pressure is met.

The invention discloses a hot extrusion variable volume percentage bearing bush type magnetorheological fluid brake. The hot extrusion variable volume percentage bearing bush type magnetorheological fluid brake comprises a brake shell, a brake shaft and a base; one part, in the brake shell, of the brake shaft is expanded to form a brake section; a magnet exciting coil and a magnetism isolating friction ring are arranged in a brake cylinder; an accommodating groove is formed in the brake section; a friction top block, a guide column and a shape memory alloy spring are arranged in the accommodating groove; a bearing bush is arranged on the external side of the brake section; a shaft hole is formed in the right end of the brake shaft; an oil guide hole is formed in the middle part of the brake section; the inner end of the oil guide hole communicates with the shaft hole; the middle part of the oil guide hole communicates with the accommodating groove; a filter is arranged at the outer endof the oil guide hole; the bearing bush is connected with the filter in a sliding fit manner; magnetorheological fluids are filled between the external wall of the bearing bush and the internal wallof the brake shell; and the shaft hole, the oil guide hole, a connecting hole and the accommodating groove are filled with silicone oil. The hot extrusion variable volume percentage bearing bush typemagnetorheological fluid brake has the advantages that the stability and reliability of the brake can be guaranteed in a high temperature environment, the braking performance can be guaranteed, and the braking effect can be improved.

The invention discloses a phase change type magnetorheological material and a preparation method thereof. The phase change type magnetorheological material comprises the following materials in part by mass: 38.2-69.1 parts of base materials, 30-60 parts of magnetic particles and 0.9-1.8 parts of surfactant. The base materials comprise paraffin wax and albolene, and the mass ratio of the paraffin wax to the albolene is 1.5:1-1:1.5. The magnetic particles are carbonyl iron powder. The phase change type magnetorheological material has a high magneto-induced effect and high stability, has the physical property of non-solvent type magnetorheological elastomer at room temperature, is converted into a fluid state from a viscoplastic state at high temperature (about 50 DEG C) due to the phase change performance of the base materials, and has typical characteristics of magnetorheogical fluid, namely, the phase change type magnetorheological material can be freely converted from magnetorheogical fluid to magnetorheogical elastomer or from the magnetorheogical elastomer to the magnetorheogical fluid along temperature change.

The invention provides a method for preparing a magnetorheological elastomer with high heat resistance and tensile properties, comprising the following steps: a. Mixing modified carbonyl iron powder, silane coupling agent and methyl vinyl in an internal mixer The silicone rubber is mixed evenly, so that the surface of carbonyl iron powder is coated with a polymer composed of methyl vinyl silicone rubber and silane coupling agent, and then EPDM rubber, plasticizer and reinforcing particles are added for full mixing. Refining to obtain the mixed rubber; b. Put the mixed rubber in the open mill, add anti-aging agent and vulcanizing agent to carry out the rolling and rolling, and then inject the obtained material into the mold, and carry out pre-structural treatment under the magnetic field , and then vulcanized on a flat vulcanizer to obtain a magnetorheological elastomer with high heat resistance and tensile properties. The preparation method of the invention can overcome the technical difficulties in preparing the magnetorheological elastomer by using the EPDM rubber, and exert its excellent performance.

The invention relates to the field of intelligent magnetic materials and in particular relates to a graphene @Fe3O4 compound water base magnetorheological fluid and a preparation method thereof, solving the problems that existing magnetorheological fluids are easy to settle and the stability and magnetorheological effects of the magnetorheological fluids are difficult to optimize at the same time. The preparation method comprises the following steps: preparing a Fe3O4 water base magnetic fluid with FeCl2.4H2O and FeCl3.6H2O; sequentially adding concentrated sulfuric acid, potassium permanganate and hydrogen peroxide to natural flake graphite and sodium nitrate to prepare graphite oxide; and then carrying out ultrasonic dispersion on home-made graphite oxide to prepare graphene oxide, finally adding a surfactant, the Fe3O4 water base magnetic fluid and a reducing agent to graphene oxide, washing the solution with deionized water until the solution is neutral, and then dispersing graphene @Fe3O4 compound magnetic particles in the deionized water to undergo ultrasonic dispersion, removing the precipitates and taking the supernatant, namely the stable graphene @Fe3O4 compound water base magnetorheological fluid, wherein the magnetic particles are graphene @Fe3O4 and account for 5-35wt% of the whole. The method has the advantages of good stability, low zero field viscosity, high shear strain and wide operating temperature range.