Research On Modal Analysis Of Mounting System Of ATV Powertrain And Optimization Of Mounting Parameters

The powertrain is the main vibration source of the vehicle,and the vibration characteristics of its mounting system directly affect the NVH performance of the vehicle.The modal analysis of powertrain mount system and the optimization of mount parameters can improve the vibration isolation performance of the suspension system and reduce the possibility of coupled vibration.This paper takes the ATV powertrain suspension system as the research object,and the research mainly includes:(1)On the basis of analyzing the basic principle of mass line method,the inertial parameter identification test of the ATV powertrain was carried out.Apply 3D scanning technology to the measurement of excitation point and response point;A threedimensional model of the ATV powertrain was constructed by reverse modeling technology.Based on the 3D model,the position of the rubber suspension mounting point is obtained,and the inertia parameters of the ATV powertrain are calculated.By comparing the inertial parameters identified by the excitation points of different excitation quantities,at least 19 excitation points and 8 three-way response points can be obtained to identify stable inertial parameters.(2)Based on the super-elastic constitutive theory and viscoelastic constitutive theory of rubber materials,the static loading test and simulation calculation of rubber suspension were carried out.By comparing the load-displacement curves obtained by test and simulation,the accuracy of the rubber mount model was verified.The static stiffness and dynamic stiffness of the rubber suspension are calculated,which provides accurate stiffness values for subsequent modal analysis.By analyzing the change of rubber mount dynamic stiffness value with frequency,it is concluded that there is a positive correlation between rubber mount dynamic stiffness and loading load frequency.(3)On the basis of analyzing the vibration isolation theory,the influence of the value range of the natural frequency on the vibration isolation performance is studied.Based on the energy decoupling method,multibody dynamics software and finite element software,the model of ATV powertrain mounting system was established.Based on the above model,the rigid body mode frequency and decoupling rate of the ATV powertrain mount system were solved respectively.The results of the three methods are basically consistent,so the accuracy of the solution results is judged.Based on the energy decoupling method,a program for solving the rigid body mode frequency and decoupling rate of the four-point suspension system was independently developed.The modal characteristics of the ATV powertrain mount system are analyzed in detail,and it is concluded that the frequency distribution of rigid body mode is unreasonable,and the coupling of pitch mode,roll mode,longitudinal mode and vertical mode is serious.(4)Through the sensitivity analysis of the mounting position and mount stiffness parameters,the optimal value range of the mounting position and mount stiffness parameters was determined.Based on the GRSM algorithm,the rigid body mode frequency of the ATV powertrain mount system is between 8～30Hz and its rigid body mode decoupling rate is greater than or equal to the set value as the constraints,and the vertical mode decoupling rate and roll mode decoupling performance are the best optimization goals,and the appropriate mounting position and rubber mount dynamic stiffness value are optimized.The decoupling of lateral mode,vertical mode,roll mode and horizontal swing mode is realized through the optimization of suspension parameters,the decoupling rate of longitudinal mode and pitch mode is improved,and the vibration isolation performance of the mount is enhanced.In order to verify the feasibility of optimizing the rear suspension parameters,the forces of each suspension under the optimized front and rear brake conditions were compared.The displacement of each suspension of the optimized powertrain mount system under the braking condition was analyzed.The feasibility of the optimized suspension stiffness and mounting position is verified by data analysis.