Research On Constitutive Model Simulation And Nonlinear Dynamic Modeling Of Automobile Powertrain Rubber Mount

In recent years,the automobile industry of our country has developed rapidly.With the improvement of people’s living standards,vehicle NVH(Noise,Vibration,Harshness)performance has been put forward higher requirements by people.The powertrain system is one of the main sources of vibration and noise in vehicles.As a key component to isolate the excitation force transmission between the powertrain and the body,Powertrain mount components have a great impact on the NVH performance of the vehicle,so it is necessary to conduct in-depth research on it.This thesis takes a certain commercial vehicle powertrain rubber mount as the research object,starting with the hyperelastic and viscoelastic properties of rubber materials,analyzing and studying the mount characteristics and its dynamic modeling technology.The main research work includes following:Firstly,the hyperelastic constitutive theory of mount rubber materials is described,and the hyperelastic constitutive model of rubber materials is analyzed.According to the national standard,the uniaxial tensile test under different maximum strain levels of rubber materials was completed.The particle swarm algorithm was used to identify the parameters of five hyperelastic constitutive models,and the fitting results of different hyperelastic constitutive models to the experimental data were discussed,and the selection strategy of hyperelastic constitutive model based on uniaxial tensile test.After comparing with the recognition results of Abaqus software,it is found that the particle swarm algorithm can obtain more accurate constitutive model parameters.Secondly,the classical viscoelastic constitutive model and the fractional derivative-based viscoelastic constitutive model of rubber materials are analyzed respectively,and the fractional derivative order in the fractional derivative-based viscoelastic constitutive model is discussed in relation to the storage modulus,loss modulus,and the influence of loss factor.After the dynamic characteristic test of the rubber specimen was carried out,the test data of the rubber material dynamic modulus of the specimen under different frequencies and different maximum amplitudes were obtained.Then,particle swarm algorithm was used to identify the parameters of the six viscoelastic constitutive models and the identification results were discussed,eventually,the errors of the viscoelastic constitutive models and the experimental results were compared.Third,a finite element model of the front and rear mount of the powertrain was established in Abaqus,after static and dynamic tests were performed on the rear mount specimens,the static stiffness and the dynamic stiffness at different excitation frequencies under two amplitudes were obtained.By using the built finite element model to simulate and analyze the static stiffness of the front and rear mount under five different hyperelastic constitutive models of rubber materials,and compare the Z-direction simulation results of the rear mount with the experimental data,it is found that the Mooney-Rivlin model has the smallest error.At the same time,a finite element model considering hyperelastic and viscoelastic constitutive models was used to simulate and analyze the Z-direction dynamic stiffness of the rubber mount at different frequencies and different amplitudes,and we found that the simulation results are generally consistent with the experimental data.Finally,based on the above analysis,a non-linear dynamic model of rubber mount is established that takes into account the effects of elastic force,viscous force and friction force.Based on the parameter identification of the model,the numerical solution method of the built nonlinear dynamic model is studied and the model is solved.Through the impulse response test of the rear suspension,the model calculation results are verified,and the results show that they are in good agreement with the test data.It shows that the nonlinear dynamic model built in this thesis can better describe the dynamic characteristics of the rubber mount,and has certain engineering application value.