Multi-objective Optimization Of Multi-mode Magnetorheological Mount Structure Based On Vehicle Vibration Control

With the development of the automobile industry and the improvement of people’s consumption level,cars have become a common travel tool for people,but the large number of cars have brought huge pressure to the natural environment.In response to the national energy-saving and emission-reduction policies,car’s lightweight has been emphasized and developed.However,while the car is lightweight,it also brings more vibration and noise problems to the car.The engine mount can not only improve the vibration and noise problems in the car,improve the comfort of the car,but also effectively protect the powertrain and prolong the service life of the engine.In order to adapt to the car’s lightweight technology,the mount with excellent performance has become an urgent need to improve the quality of car’s NVH.Semi-active hydraulic mount has good vibration isolation effect,and its structure is relatively simple and energy consumption is low.It has been applied in advanced passenger vehicles.It is of great significance to study the semi-active mount of powertrain for the improvement of vehicle NVH performance.As a new type of intelligent material,the viscosity of magnetorheological fluid(MRF)changes rapidly with the external magnetic field,which can realize the transfer of force or torque and the dissipation of vibration energy.Therefore,the magnetorheological(MR)mount with controllable performance,low energy consumption and fast response can be applied to automotive powertrain mounts.In terms of dynamic performance,the MR mount can not only better meet the requirements of powertrain vibration isolation,but also overcome the shortcomings of traditional mounts to achieve real broadband vibration isolation.The main content of this paper is as follows:(1)The structure design of MR mount,dynamic model and the current research status of mount and system optimization at home and abroad are described.Aiming at some of the problems existing in the current structural design and optimization methods,the main research content of this article is proposed.(2)The working principle of MRF and powertrain mount is described,and a mixed mode MR mount with squeeze mode and shear mode is designed and its structure and working principle are described.Furthermore,according to the fluid theory,the output damping force of the magnetorheological fluid in the damping channel in the squeezeshear mixing mode is deduced,and the squeeze-shear mixed mode magnetorheological mount’ dynamic model is established by ignoring the elastic restoring force of the rubber main spring and process the mount sample to test and verify it.(3)Based on ANSYS APDL magnetic circuit simulation analysis,the influences of the internal structural parameters and external excitation conditions on the magnetic induction intensity in the damping channel of the squeeze and shear mixed mode MR mount were studied.Further,according to the structural parameters of MR mount dynamic model to draw and output force of incentive conditions on the damping channels are studied.(4)Consider the squeeze and shear mixed mode of MR mount dynamic model,based on MATLAB/Simulink built 10 degrees of freedom vehicle dynamics model,the in-line four-cylinder engine vibration excitation and pavement impact incentive effect on the vibration of the vehicle are analyzed,and extract the seat slideway in a speed bump,moving at a constant speed,and the time-frequency characteristics of start-stop condition.(5)Aiming at the shortcoming that the optimization results of the mount system based on the vehicle model could not guide the structure design of the mount body,a collaborative simulation optimization platform was built by using ISIGHT,ANSYS/APDL and MATLAB/Simulink.Taking the time-frequency characteristics of the seat as the goal,the sensitivity analysis of the structure parameters of the magnetorheological mount is carried out.The time-domain and frequency-domain multiobjective optimization of the structure parameters are carried out.Through simulation and comparative analysis,the results show that the mount’s vibration isolation ability of optimization based on the vehicle model has a better vibration isolation effect.