Research On Design And Controllability Of Torsional Vibration Damper Based On Magnetorheological Grease

Crankshafts are one of the core component of engines,and its torsional vibration affects the service life of crankshafts.Therefore,it is necessary to use the crankshaft torsional vibration dampers to reduce the torsional vibration,and dissipate torsional vibration energy.The silicone oil shock absorbers are widely used in automotive diesel engines and marine diesel engines as a typical inelastic damping shock absorber.However,the damping coefficient of the current silicone oil torsional vibrator widely used is fixed and the key damping parameters of the device cannot be adjusted adaptively according to the real-time response requirements to achieve the best vibration control effect.Currently,the MR fluid materials are widely used in adaptive vibration reduction control due to their advantages,such as fast response speed,continuously adjustable,low energy consumption,etc,which can make up for the limitations of conventional silicon oil's fixed damping work.However,MR fluid materials are prone to sedimentation.And the requirements for sealing are more demanding.Therefore,this paper uses the MR grease which is not easy to settle to design the engine torsional vibration damper.The main contents include:(1)Modeling and simulation analysis of torsional vibration damping system:First of all,the crankshaft torsional vibration reduction system is theoretically analyzed and studied,overall modeling and simulation analysis of torsional vibration damping system through MATLAB/Simulink,and the influence of important parameters in the shock absorber on the torsional vibration control effect is analyzed,and simulation experiments are carried out under different working conditions.Experimental results show that,in the case of other parameters unchanged,the value of the damping coefficient of the torsional vibration damper increases,the reduction of torsional vibration is also accelerating,the value of its torsional vibration equilibrium point decreases accordingly,the further increase of the damping coefficient value will not make the value of the vibration equilibrium point continue to decrease,but will make the value of the vibration equilibrium point increase.In addition,through modeling simulation analysis of the solution formula of the amplitude amplification coefficient,it can be seen that:At different frequency ratios,the value of the damping coefficient continues to increase,and the value of the amplitude amplification coefficient changes differently.(2)Simulation analysis of electromagnetic field:The damping controllability of torsional shock absorbers mainly lies in the magnetic field.Therefore,Maxwell software is used to analyze the electromagnetic field of the pre-designed engine torsional vibration damper based on MR grease,the electromagnetic field is laid for the MR grease material existing in the gap between the torsional vibration damper shell and the inertia block.The numerical simulation results show that the magnetic field generated by the inner and outer double coils can better meet the coverage of the MR grease material between the shock absorber shell and the inertial mass,the article further analyzes the steady-state magnetic field under different current fields,get the relationship curve between the ampere turns and the magnetic field.(3)Structural design:The interaction between the inertia mass structure and the silicone oil of the traditional silicone oil shock absorber was compared,and the structural design of the overall structure of the engine torsional vibration damper and the wiring box structure based on MR grease.The suitable silicon oil model and MR grease were optimized and matched.The mechanical properties of the key parts of the designed MR grease torsional shock absorber were numerically analyzed,structure deformation under different working conditions is given to meet the technical requirements of complex working conditions.(4)Optimal control of whale optimization algorithm:The dynamic control model of the MR grease torsional vibration damping system is established,the traditional PID control method and the PID parameter tuning PID control method of WOA are respectively used to carry out numerical simulation of torsional vibration control effect.The simulation results show that the WOA tuning PID parameter control method can achieve good results,significant reduction in torsional vibration control amplitude and damping ratio.In addition,under the same number of iterations and limitations,the PID parameters control method of WOA converges rapidly.(5)Applicability evaluation of torsional vibration damper based on MR grease:In view of the parameters such as the amount of oil and thickness in the damping gap of torsional vibration damper can directly affect the vibration damping performance of the device.Therefore,in this paper,the designs of non-destructive testing scheme from the aspects of the quality of the welding seam of the device and the gap size parameters of the oil layer(grease layer)of the silicone oil cavity and the MR grease cavity,and the use of ultrasonic devices for practical measurement.The results show that the weld quality and the gap size of damping layer can be measured by ultrasonic scanning microscope,and the accuracy can meet the industrial testing requirements.