Study On The Modeling And Optimization Of Powertrain Mounting Systems

The Modeling and Optimization of Powertrain Mounting Systems (PMS) is a key technology on Vehicle Noise, Vibration and Harshness (NVH) performance research. This thesis is focus on modeling for hydraulic engine mount (HEM) with multiple inertia tracks (MIT), dynamics analysis and robust design for PMS with uncertain parameters, topology optimization for rubber mount design and dynamics analysis for mechanical system with fractional derivative damping. The main research contents are list as follows:The linear and nonlinear Lumped Parameter (LP) models for different types of HEMs with MITs are proposed. A fluid-structure interaction (FSI) and Finite element analysis (FEA) method is presented to calculate the relation between the pressure difference of upper and lower chamber to the fluid volume flux. The least-squares parameter estimation is used to identify the linear and nonlinear resistances of the inertia track. The methods for the calculation of the dynamic stiffness and loss angle are presented using the nonlinear LP models. The formulae for estimating peak frequency of the loss angle for the HEMs with MIT s are derived from the linear LP models. The influences of the numbers, the sizes and the length of the inertia tracks on the HEMs dynamic properties which include dynamic stiffness, loss angle and peak frequency of the loss angle are analyzed with the proposed models.The uncertaintity of design parameters in the PMS is dicussed. Baseed on Monte Carlo method, sensitivity analysis, response surface method (RSM) and interval analysis, the PMS with uncertain paramenters is studied. Based on RSM formulae the PMS robust design is presented. Robust design is applied to the development of the HEM.Constitutive model of rubber materials and paramenters identification method for the constitutive model are dicussed. The multi-object topology optimization model for engine mount is presented, in which the different axis stiffness, fatigure life, volume or mass are considered. The topology optimization results are validated through the samples manufacturing, testrig experiment and nonlinear finite element analysis, and this methodology can be effectually applied for the design of rubber mount.The mathematical base of the fractional calculus is presented which include the main definition, properties and the computing method for the fractional derivatives. The mathematical model for the damper is expressed by five-parameters fractional derivative model. The generalized-a scheme are applied to solve the vibration differential equations with fractional derivative damping. A new solving strategy which can dissipate the high frequery response and keep the lower frequery respone is presented and applied to dynamic analysis for vibration system with fractional derivative damper. The analytical methods are the base for solving vehicle system dynamic response with fractional derivative damping.