Analysis And Application Of Composite Transmission Theory Of MR Fluid And Shape Memory Alloy Under Thermal Effect

As new intelligent materials, mechanical properties of magnetorheological fluidand shape memory alloy can be continuously controlled by external drive source (likemagnetic field, temperature field and so on) and they have attracted great attention ofscholars at home and abroad for their distinctive mechanical properties. But most of thepresent researches are conducted with regard to material mechanical properties ofmagnetorheological fluid and application under the action of single physical field, andin application, it is the common problem that the silicone oil property ofmagnetorheological fluid will decline or disappear in high temperature condition andthere are fierce changes of materials’ properties under complex external environment.As a result, the magnetorheological effect of magnetorheological fluid in hightemperature condition declines, the change of shear stress is uncontrollable withdiscontinuous transmission problem or invalid transmission problem. To solve theseproblems and combines rheological property of magnetorheological fluid andtemperature sensing property of shape memory alloy, this paper carries out a furtherstudy about composite transmission theory and application of magnetorheological fluidand shape memory alloy under the influence of magnetic field and temperature field.And contents of relevant researches are described as follows:1) Analyze the material composition and material property of magnetorheologicalfluid, adopt digital holographic microscopy to measure microstructure ofmagnetorheological fluid in three-dimensional space, get the size of ferromagneticparticle, distribution and movement along magnetic induction line inmagnetorheological fluid as well as the whole real-time three-dimensional chain process,and analyze magnetic chain structure, chain speed, responsive time, accelerated speedand stress condition of magnetorheological fluid in magnetic field. Because of hugedifference caused by magnetorheological fluid under different temperature, analyzeviscosity-temperature characteristics of magnetorheological fluid and analyze theinfluence of temperature on viscosity of magnetorheological fluid, yield stress and shearstress.2) Analyze mechanical property of shape memory alloy, establish designphilosophy formula of shape memory alloy spring, conduct experimental measurementon temperature sensing and drive property of shape memory alloy and verify the design philosophy formula of shape memory alloy; establish the relation among output force ofshape memory alloy driver and temperature, material parameter and structure parametersubject to axial constraint under the influence of temperature.3) Combined with rheological property of magnetorheological fluid andtemperature sensing property of shape memory alloy, the paper puts forward acomposite transmission principle and method of magnetorheological fluid and shapememory alloy, designs a composite transmission device of magnetorheological fluid andshape memory alloy, which relies on magnetorheological fluid controlled by magneticfield to transmit torque in lower temperature. When temperature increases, the propertyof magnetorheological fluid decreases, shear stress becomes uncontrollable anddiscontinuous and spring-actuated friction disk of shape memory alloy is used to assisttransmitting power.4) According to theory of composite transmission, analyze property of shear stressof magnetorheological transmission device under the effect of applied magnetic field,and analyze viscoplastic shear flow of magnetorheological fluid between two cylinderswith the same axis and establish shear transmission power equation ofmagnetorheological fluid in cylinders.5) Establish design method of dual driver of partial acting-type shape memoryalloy, take push friction disk of partial acting-type driver as the auxiliary transmissiondevice of magnetorheological fluid transmission in high temperature, apply dual driverof partial acting-type shape memory alloy to the connection and separation of drivingmaster-slave friction disk and realize temperature sensing control of friction disk.Establish equation of transmission torque of composite transmission and realize thedigital control of temperature on auxiliary transmission device.6) According to transmission principle and transmission equation of compositetransmission device, the transmission part of magnetorheological fluid and auxiliarytransmission part of shape memory alloy drive friction disk have been respectivelydesigned and finally figure out selection method of two materials in design andcalculation formula of every key geometric parameter in composite transmission device;analyze and optimize the design of magnetic circuit in transmission device and analyzethe influence of working gap, arranged location of electromagnetic wire and coilwinding direction on magnetic line of force, intensity and distribution of workingmagnetic field.7) Establish an experimental scheme of composite transmission property, experiment on transmission property of composite transmission device ofmagnetorheological fluid and shape memory alloy, verify that composite transmissiondevice of magnetorheological fluid and shape memory alloy has higher stability andwork efficiency even in high temperature environment.