Analysis And Design Of Self-Power Magnetorheological Fluids Transmission Device

Magnetorheological fluids(MRF)are a new type of functional material with continuous and reversible changes in rheological properties under the action of an external magnetic field,and the magnetorheological effect of MRF is characterized by rapid response and easy control.As a new type of intelligent material with excellent mechanical properties and excellent thermal properties,Shape Memory Alloys(SMA)are commonly made into SMA springs for use in the field of mechanical engineering.Because MRF and SMA can change their material properties in response to changes in physical fields,they have a wide range of promising applications in the field of mechanical transmission.This paper addresses the high sensitivity of SMA to temperature and large recovery stresses by using the recovery force generated by SMA springs under the action of temperature to output frictional torque,thus enabling the master and slave shafts to be joined and a permanent magnet generator to power the MRF drive.This self-generating drive enables soft start of the device according to the temperature change of the device and the adaptive nature of this clutch at different speeds enables intelligent adjustment of the working gap magnetic field.The main work in full is as follows:(1)The composition of the MRF and its intrinsic model are described to provide a microscopic explanation of the MRF chain drive mechanism.Based on the Bingham intrinsic model of MRF,the variation of shear yield stress with shear strain rate is investigated for the same temperature,different MRF types and different shear strain rate conditions.(2)The special mechanical properties of SMA under temperature fields are described,the shape memory and superplasticity effects are explained in detail at the microscopic level,and the Brinson intrinsic model commonly used for their engineering applications is derived.The design of a SMA spring is based on a common coil spring,and the SMA coil spring recovery force variation law with temperature is derived.An electrothermal SMA spring structure and operating principle are presented.(3)The structure and working principle of the spontaneous electromagnetic rheological fluid transmission device are described,which mainly consists of a MRF device and a permanent magnet generating device;the derivation process of the transmission torque of MRF devices of different structures is introduced,based on which the SMA and disk MRF composite transmission device is designed to study the variation law of the magnetic field strength of the working gap with the coil current.A wedge-gap cartridge MRF device is designed,its magnetic field and flow field are analyzed,and the influence of the extrusion reinforcement effect produced by the wedge gap on the performance of the device is analyzed.(4)Based on the design data of the self-generating device,the excitation coil and rectifier circuit of the device are designed,and the key parameters of the permanent magnet generating device are calculated in conjunction with the permanent magnet generator mechanism and key structural dimensions.(5)The finite method is used to simulate the electromagnetic field of the transmission device designed in the paper,and analyze the disk composite transmission device to obtain the variation law of the magnetic field strength of the working gap with current;based on the multi-physics field analysis of the cartridge gap and wedge gap,to study the influence of the wedge gap on the transmission device,the simulation results show that the wedge gap can effectively increase the shear yield stress of the MRF,and can transmit a larger torque.The influence of the number and position of the coils on the magnetic field and temperature field of the MRF device was quantitatively analyzed.(6)The recovery force characteristics of SMA spiral springs were analyzed,and an experimental platform for the recovery force characteristics of SMA spiral springs was established and relevant experiments were carried out.The results show that the recovery force of SMA spiral springs increases with increasing temperature and decreases with decreasing temperature,and the trend of change between the theoretical and experimental values is basically the same.