Analysis And Design Of Magnetorheological Variable Area Transmission Device Driven By Shape Memory Alloy

In recent years,intelligent materials have been widely used in various fields.As new smart materials,magnetorheological fluid(MRF)and shape memory alloy(SMA)have attracted much attention of researchers at home and abroad due to their unique mechanical properties.In this paper,based on the rheological behavior of MRF under external magnetic field and the shape memory effect of SMA under temperature change,a variable area transmission method of MRF driven by SMA is proposed.The working area of MRF is changed by the temperature sensing property of SMA to realize the change of the transfer torque.Based on the theory of mechanical design and electromagnetic field simulation technology,the relevant transmission principle,transmission performance,design theory are studied.It provides a theoretical basis for the development of new intelligent transmission devices with simple structure,easy control,stable operation,safety and high efficiency.The main research work of this paper is as follows:(1)The composition,rheological mechanism and constitutive equation of magnetorheological fluid are introduced.The performance index and influencing factors of MR fluid are analyzed.The characteristics and constitutive equation of shape memory alloy are introduced.(2)Based on the Bingham model,the torque expressions of disk and cylinder magnetorheological transmission are established,and the composition and influencing factors of transfer torque are analyzed.According to the mechanical properties of shape memory alloy and the design theory of cylindrical spiral spring,the design theoretical formula of shape memory alloy spring is deduced,and the temperature sensing property of the spring is analyzed.(3)The working principle of magnetorheological variable area transmission device driven by SMA is described,and the transmission performance of disk-type and cylinder-type magnetorheological variable area transmission device is analyzed respectively.(4)According to the working characteristics of the magnetorheological variable area transmission device driven by SMA,and the requirements of the transmission torque,the key structural parameters of disk-type and cylinder-type magnetorheological transmission device with variable area are designed.(5)Based on the magnetic circuit design method,design the magnetic circuit of the disc and cylindrical magnetorheological variable area transmission devices respectively,and carry out finite element analysis at the same time.The influence of structure size and excitation coil arrangement on the magnetic circuit and magnetic induction intensity of the magnetorheological variable area transmission device is investigated.(6)The experiment verifies the corresponding relation between delivery stroke of SMA and temperature index.