Research On Structural Optimization And Dynamic Performance Of Magneto-rheological Damper For All Terrain Vehicle

Because All-terrain Vehicle(ATV)is usually driven on uneven roads,the traditional suspension system cannot meet the vibration reduction requirements due to the fixed damper parameters.The semi-active suspension based on magnetorheological damper has attracted more and more attention in the field of vehicle vibration reduction owing to its advantages of adjustable parameters,low power consumption and fast response.The damping force,the dynamic range of the damping force and the response time of the magnetorheological damper directly determine the vibration suppression performance of the magnetorheological semi-active suspension system.Therefore,in this paper,to improve the performance of magnetorheological dampers,the following aspects are studied:(1)According to the requirements of ATV on magnetorheological damper,the structure and working mode of the magnetorheological damper are determined.Aiming at the magnetorheological fluid selected in this paper,the mathematical relationship between its yield stress and magnetic field strength is established based on the test data.On this basis,the main factors that affect the performance of the magnetorheological damper are analyzed.(2)The mechanism of magnetic flux density induced in the magnetorheological fluid flow gap was theoretically analyzed.Based on this,the mathematic model between piston structure parameters and magnetic field strength were established by combining the finite element method(FEM),design of experiments(DOE)and response surface methodology(RSM).The linear and quadratic response surface models related to the magnetic field strength was introduced and the accuracy of the models were verified by the R~2 value.The results show that the R~2 value of the quadratic response surface model reaches 0.9930,which can more precisely describe the response of the electromagnetic field in the magnetorheological fluid flow gap.(3)Taking the Coulomb damping force of the magnetorheological damper,the dynamic range of the damping force and the internal circuit time constant as the optimization objectives,the genetic algorithm is used for multi-objective optimization,and the performance of the damper before and after optimization are compared.Result shows that,the overall performance of the optimized magnetorheological damper is increased by 30.6%.In addition,for the purpose of reduce the time response of the magnetorheological damper,a piston with a grooved structure was designed to suppress the eddy current effect,and the grooved piston was simulated and analyzed by the finite element simulation software ANSYS.The simulation results show that the grooved piston can reduce the time response of magnetic induction in the magnetorheological fluid flow gap by 35.3%compared to the non-grooved piston.(4)According to the testing methods of the damping force and response time of the magnetorheological damper,the constructed test system is used to evaluate the performance of magnetorheological dampers with various piston configuration.The test results of the damping force show that,the maximum damping force of the damper is increased by 23.7%during compression and 31.6%during rebound compared with that before the optimization using the genetic algorithm.The dynamic range of damping force increase by a maximum of 151.2%.The test results of the response time show that,the response time of the damper with grooved piston is reduced by a maximum of 57.4%compared with damper with non-grooved piston.