Study And Design Of The Shape Memory Alloy And Magneto-rheological Fluid Composite Transmission Under Thermal Effect

With the driving of the vehicle, the engine will constantly converts chemicalenergy into mechanical energy and thermal energy. The size of the heat whichgenerated by the engine is transformed by the changes in road conditions and workingcondition, therefore, the excessive heat is dissipated by engine cooling system toensure the engine working in normal condition. In this paper, based on temperaturesusceptibility and drive characteristic of the shape memory alloy, it can be made intothe bias two way actuator; based on the characteristic that magnetic induced yieldstress is changed by the magneto-rheological fluid in which external magnetic filedstrength, it can be used as torque transmission medium; used the design method whichcombined both mechanical design and magnetic circle design, developed acomposite transmission device which composed of SMA and MRF, it can achieveintelligent start or stop depending on the temperature level, can be used intoheavy-duty truck fan clutch for adjust the engine heat conditions, have a smooth startand stop,no vibration, no wear and other excellent characteristics. Paper work fromthe follow aspect:1) The spring of SMA is an important part of the bias two way actuator. Based onthe properties of the shear modulus of elasticity of SMA and temperature, we create amathematical model of the SMA spring. At different temperatures, we can get therelationship of output power and displacement, which can reflect the characteristics ofSMA spring. According to the experiments, we can complete the design of the drive,which is used to control the start-stop of the intelligent device.2)Based on the Bingham constitutive model of MRF, we analysis thecharacteristics of the shear yield stress of MRF between two cylinders, then producingthe mathematical model of transmission torque. In order to complete the design of, werefer to the original data and the critical geometry, combining with mechanical designand application of the average magnetic method.3)Because of the uncertain relationship between the magnetic and structural ofthe device, we use to analyze its simplified model, then obtaining the relationshipbetween magnetic flux density of working gap and working gap width, trunking depth,winding arrangement methods,which provide the reference to improve the magneticcircuit.4)After the analysis of the ANSYS, we find that the arrangement of magnetic coil should be improved. So we chose the different winding arrangement methods,which can increase the effective axial length of MRF, reduce the maximum magneticflux density of driven outer cylinder wall and enhance the transmission performanceof the device. We use the optimal design method APDL to optimize structure size andachieve good results.5)We build transmission performance test bench to complete the experiment ofMRF transmission driven by SMA, which has been shown that the values of thetorque calculated by the model agree with experimental data.