Multi-objective Optimization And Structural Design Of A Heavy Truck Powertrain Mount

With the gradual maturity of China’s auto market and the formulation of relatively complete policies by the country and the government,various auto companies have paid more attention to the NVH performance of automobiles.The engine is one of the main vibration sources during the driving process of fuel vehicles,especially in the starting stage of the car,so when the vibration source of the engine is transmitted to the body and other components,it is necessary to make the transmission rate as low as possible.At present,the study of engine vibration characteristics has become a very important research topic in vehicle development.After a lot of experiments,it is found that there are two contradictions in the process of developing and designing the suspension system.On the one hand,in order to make the power If the movement range of the assembly is small,the mounting system needs to have greater stiffness;on the other hand,in order to make the mounting system have good vibration isolation,it is required that the mounting stiffness should not be too large.The optimal design of the mounting system in this subject is to find a suitable solution between limiting the excessive displacement of the powertrain due to the force and better vibration isolation performance.The following work has been done:1.Use the parameters of the engine and transmission under different reference frames provided by the manufacturer to convert them into the parameters of the powertrain under the powertrain coordinate system.2.Use the View module in the ADAMS software to simulate the powertrain mounting system to obtain the modal values of the six degrees of freedom of the powertrain and the corresponding energy decoupling rate;analyze and evaluate the calculation according to the vibration isolation theory As a result,it is found that the original scheme does not conform to the vibration isolation theory and needs to be optimized.3.Using python software combined with decoupling theory and genetic algorithm to write a program to re-optimize the original scheme,in which the three-dimensional stiffness of all mounts is selected as the optimization variable,and the optimization objective is the decoupling rate of the mount system in six directions,The natural frequency of the mounting system,the interval difference between the frequencies,and the range of stiffness are used as constraints.After recalculation,the requirements of the enterprise are met.4.For the optimized mount stiffness,the curve design needs to be redesigned.After the stiffness curve is designed,it needs to be checked with the North American28 working conditions.The powertrain displacement and rotation angle are used as check factors.The load on the suspension provides relevant data for the check and optimal design of the bracket below.5.According to the structural characteristics,the initial front and rear mount models are redesigned,and the mount model conforming to the designed stiffness curve is designed based on the simulation analysis results of ABAQUS.The fatigue simulation analysis of the modified model is carried out,and the results show that it meets the requirements of the enterprise.6.The strength of the front and rear brackets of the suspension was checked,and it was found that the front suspension did not meet the conditions.The unsatisfactory front bracket was optimized and the strength was checked again.The calculation results showed that the strength requirements were met.During the research process of the project,some practical innovations in application have been obtained,as follows:Based on python software combined with multi-objective genetic algorithm,it points out a more accurate direction for the optimization of the mounting system.From the initial model of the suspension system to the optimization model,a series of calculation processes provide theoretical and manufacturing guidance for the subsequent design,modification and strength checking of the suspension structure.