Study Of High-frequency Dynamic Stiffness Of Double-isolation Rubber Mounts

With the development of social economy,the automobile industry is showing a prosperous scene.Meanwhile,the requirement for riding comfort is improving constantly.At present,most of the powertrain mounts used in electric vehicles are traditional rubber mounts.However,obvious vibration and noise problems occur at high speeds.In order to handle these problems,the double-isolation rubber mount is researched in this paper.The main works of the paper are:1)The hyperelastic and viscoelastic constitutive models of rubber material are studied.The MR-generalized Maxwell superposition model is selected as the constitutive model in this paper after comparing the characteristics of different models.The high-frequency dynamic shear test of rubber pieces is designed and carried out.The viscoelastic constitutive model parameters are identified according to the test results and used in Abaqus(a finite element analysis software).2)The calculation method of high-frequency dynamic stiffness of rubber mount is proposed.Taking a typical rubber mount as an example,the process of establishing the finite element model and the calculation method of high-frequency dynamic stiffness are introduced in detail.High-frequency dynamic test of this mount is performed,and the calculation method is verified by comparing the finite element calculation results with the test results.This paper introduces the phenomenon of "internal resonance" when the rubber mount is subjected to highfrequency excitation.And the factors affecting the dynamic stiffness of mounts are analyzed by simulation.3)The high-frequency dynamic stiffness of the double-isolation rubber mount is analyzed.The structure of double-isolation is introduced through a double-isolation rubber mount of torque strut type.The dynamic stiffness of the main spring,the bushing and the entire doubleisolation rubber mount are calculated.The result shows that the double-isolation rubber mount has better high-frequency vibration isolation performance.The high-frequency dynamic experiment of the double-isolation rubber mount is carried out.The influence of the additional mass and the loading area on the dynamic stiffness is analyzed through the experiment.The double-isolation rubber mounts of main spring-bushing type and double-bushings type are introduced,and their dynamic stiffness is calculated through finite element analysis.All different structural forms of double-isolation rubber mounts show smaller high-frequency dynamic stiffness.The additional mass causes a dynamic stiffness peak at a lower frequency which is similar to the "natural frequency" of the system.And this "natural frequency" peak determines the low-frequency vibration isolation performance of double-isolation rubber mounts to a large extent.The factors affecting the dynamic stiffness of double-isolation rubber mount are analyzed,including additional mass,material constitutive model parameters and preload.4)The equivalent mechanical model and mathematical model of double-isolation rubber mount are established.The equivalent mechanical model of single-stage rubber mount,the concepts of drive-point stiffness and cross-point stiffness are introduced.Based on the singlestage rubber mount,the equivalent mechanical model of double-isolation rubber mount is obtained,and the physical meaning of parameters in the model are explained.According to the mechanical model,the mathematical model of dynamic stiffness is derived.