Design And Test Of Powertrain Mount And Mounting Bracket

As a chassis component,powertrain mount has the functions of supporting powertrain,buffering,damping and noise reduction,which has an important impact on vehicle comfort.In this paper,the design method of mount and mounting bracket is studied based on the powertrain mounting system of a certain model.The main work is as follows:(1)The multi-body dynamic model of powertrain mounting system is established.The load applied on the centroid of powertrain under different working conditions is taken as input to calculate the load of mount.By means of iterative calculation,the nonlinear stiffness of the mount is adjusted to realize the displacement control design of the centroid of the powertrain,which provides the basis for the design of the mount and the mounting bracket.(2)Design of the force-displacement characteristic of the mount.The force-displacement characteristics of the three main stiffness directions of the left and right mount are designed by considering the displacement control of the centroid of the powertrain,the loads of the mounts under different working conditions as well as the target linear stiffness.According to the design goal,the type selection and structure design of the mount are completed.The left mount is compression type while the right mount is composite type.A design method is proposed to study the influence of different design parameters of bump block on its stiffness characteristics.(3)Structural design and optimization of mounting bracket.According to the layout space of the mounting system and the mounts’ structure,the mounting bracket structure are designed preliminarily.According to the requirements of static strength design,the multi-objective topology optimization of the mounting bracket is carried out.The secondary design of the bracket structure and size is carried out according to the optimization results and common design philosophy,and the design parameters are optimized to realize the reasonable distribution of material.Particularly,the von Mises stress of the left bracket decreased by 51.5% on the basis of previous analysis results,and the maximal principal stress of it decreased by 56.1%,so the overall strength has been greatly improved.After optimization,the mass of the left bracket and the right bracket decreased by 11.2% and 15.5%,respectively.(4)Performance analysis of mount and mounting bracket.The finite element model of the mount is established,and the force-displacement characteristics of the three main stiffness directions of the mount are predicted by simulating the static loading during the actual test of the mount.In this paper,a new method is proposed to decompose the load acting on the bracket into the static load transmitted by the main spring and the bump block,and analyze the static strength of the bracket.The first and second restrained modes of the mounting bracket are obtained by modal analysis.Combined with the road spectrum and material S-N curve,the fatigue durability analysis of the mounting brackets is completed,and the risk of fatigue failure is predicted.(5)Performance test of mount and mounting bracket.The force-displacement characteristics of the left and right mounts are tested.The deviation between test results and finite element analysis results is within ±15%.The validity of the finite element analysis method and the reliability of the mount performance are verified.The static strength and fatigue strength of the left and right bracket were tested respectively.The test results show that the two brackets meet the requirements of static strength and fatigue durability.