Research On Internal Vibration Control Of Vehicle Based On Transfer Path Analysis

After one hundred years of development,the car has become irreplaceable consumer product in people’s daily life.At the beginning of the car,people only used it as a means of transport to narrow the distance between people.However,with the advancement of science and technology and the popularization of automobiles,people are paying more and more attention to the ride comfort of automobiles.An expert once said: "whether the car driving is comfortable,NVH performance occupies the half ".For the analysis and control of NVH performance,how to quickly diagnose the cause of the problem and put forward effective improvement measures is crucial.Based on the cooperation project with an enterprise,aiming at a light bus produced by it,the total integrated vibration contribution of each transfer path to the response point is calculated by the combination of experiment and finite element simulation.By optimizing the stiffness of the rubber bushing at the main vibration transfer path,the internal vibration level is ultimately improved.Firstly,the analytical accuracy and model building period of three different TPA methods are compared.For the requirement of analytical accuracy,the research method of this paper is confirmed as traditional TPA.The basic principle of the traditional TPA method is introduced,and the importance of accurately obtaining structural load and structure FRF(Frequency Response Function)is clarified from the theoretical formula.The inverse matrix method is selected for identifying structural load and the application of SVD(singular value decomposition)in inverse matrix method is introduced detailedly.For the acquisition of structure FRF,the coherence function method and modal superposition method are respectively deduced in detail,which lays the foundation for the experiment and simulation of TPA.Secondly,the TPA model with 15 inputs and 6 outputs is established after properly simplifying the excitation source of the vehicle.The experimental outline is designed and then the road condition test and the indoor hammer test are carried out.By analyzing the working condition data,the problem condition of the sample car and the main vibration direction of the response points are confirmed.The total integrated vibration contribution of each transfer path to the response point is calculated by adopting a contribution analysis method which considers both amplitude and phase.The vibration transfer rate of the engine mount system is analyzed,the structural load and the characteristics of structural FRF of the passive side of the excitation source are compared,and the cause for the internal vibration of the vehicle is pointed out.Then,based on the idea of finite element,a complete vehicle finite element model,including body-in-white,frame,doors and window glasses,is built with HyperMesh.After calculating the modal,based on the modal superposition method,the structure FRF of each transfer path is calculated with Virtual.Lab,and then the total integrated vibration contribution of each transfer path to the response point is calculated,which is compared with the experimental TPA results to verify the correctness of the finite element model.Finally,the Adams software is used to establish the rigid model of the subsystems of the chassis,and the flexible body and frame are connected to form the rigid-flexible coupling dynamic model of the vehicle.Determine the optimal design variables,design the combined experiment and use the dynamic model to simulate to obtain the quadratic regression mathematical model between the response point vibration and the design variables.Considering the response point vibration and the energy decoupling rate of the mount system,the total integrated objective function is obtained.The optimal solution of each variable is obtained by using genetic algorithm with Matlab,and the improved effect is predicted by simulation.