Design And Optimization Of Vibration Isolation Matching For XMQ6829 Bus Powertrain Mounting System

The vibration isolation performance of the bus powertrain mount system will be directly affect by matching of local dynamic stiffness and parameters,which determine the ride comfort performance.Aiming at the severe vibration and steering wheel jitter in idling vehicle of XMQ6829 bus,the vibration isolation of its mounting system is studied according to the relevant theories and methods.The main research contents are as follows:Focusing on the local dynamic stiffness of the powertrain mount system,the frame model of the vehicle is constructed by the finite element method,aiming at the insufficient transverse stiffness of the rear of the frame.A method of steel thickening and structural improvement on the rear girder of the frame is presented.The local structure of the mount system at the rear of the frame is redesigned,and the lateral stiffness of the frame is strengthened.The first six modal parameters are obtained by analyzing the vehicle mode.Based on the elastic center method,the impact center theory and the torque axis theory,the layout of the mounting elements is determined.The vibration model of powertrain mount system is used,and the diagonal decoupling of stiffness matrix is implemented.The stiffness and mounting position of the mounting element are matched,which natural frequency and modal vector of the mount system are solved and compared with the modal parameters of the whole vehicle.On this basis,the energy decoupling method is used to evaluate the merits and demerits of the parameters matching of the mount system.From the multi-objective optimization theory,an optimization model with the stiffness(discrete type)and position(continuous type)of mounting elements as design variables is proposed to maximize the decoupling rate.In the integrated environment of MATLAB and iSIGHT,the Adaptive simulated annealing algorithm is called to find the optimal parameters of the mount element,which meets the requirements of decoupling rate and natural frequency distribution of the mount system in various modes,and realizes the optimization of the isolation performance of the mount system.Based on the above research,the third generation XMQ6829 mounting system vibration isolation rate and vehicle acceleration test are carried out.The validity of the local dynamic stiffness enhancement and the rationality of parameter matching are verified.The vibration isolation performance of the mount system is improved.The problem of excessive vibration in the vehicle is solved and the comfort of the whole vehicle is improved.