Analysis And Design Of Automobile MR Shock Absorber

Magnetorheological (MR) fluids are suspensions of micron-sized, magnetizable particles in a carrier fluid such as synthetic oil and silicone oil, which are regarded as the intelligent materials that respond to an applied magnetic field with a change in their rheological properties. In the absence of an applied magnetic field, MR fluids exhibit Newtonian-fluid-like behavior. Upon application of a magnetic field, MR fluids can change from Newtonian fluids to Bingham plastic solids of high viscosity and low flow momently reversibly,which have a certain yield stress, and it increase with the magnetic field strength increasing.Base on the rheological properties of MR fluids, combined with the method of Machine design, the gap' flow state of of shock absorber is analysed,and design method and theory of MR shock absorber are established.The main research of the paper are as follows:(1) Constitute of MR fluids ,MR effect,the main performance and five kinds of MR fluids and performance are introduced.(2) Base on Navier-Stokes and Bingham mode, combined with the working principle of the MR shock absorber, MRF's flow in the shock absorber is analysed,and the flow eauqtion is derived, consequently,the relation between damping force and yield stress,channel's length, channel's gap is gained.(3) Base on damping force' requirement, the basic structural parameter and dimension are confirmed, and base on it, magnetic back track is designed, the length of piston is gained, meanwhile the relation of damping force,power and exciting current are gained respectively.(4) Utilize ANSYS software to carry out the imitation optimization analysis of magnetic back track and fluid analysis,and the relation of damping force versus gap,damping force versus length are imitated.(5) The experiment scheme of MR shock absorber is established.In this dissertation the innovations are summarized as follows:(1) Base on Bingham mode and blended working mode , combined with the working principle of the MR shock absorber, the MRF's viscoplastic flow eauqtion is derived, which reveals real flow state of MRF in damping channels. (2) Through analysis of data,the relation of single channel's pressure drop and yield stress is gained,which provides the method of exciting current controlling damping force.(3) The key dimensions of MR shock absorber are gained theoretically,and considering power loss aim at its magnetic back track structure design,which more truly gain the relation of damping force and exciting current, power respectively.