Model Based Virtual Prototyping for Hydraulic Passive Engine Mount with an Emphasis on Inertia Track

This thesis presents modifications of the hydraulic engine mount prediction program, HEMPP, which is currently used in the automotive industry to match the mount to the experimental results by predicting the dynamic stiffness and phase angle of the mount. The main focuses of this thesis are the identification, simulation, and verification of a new model for measuring pressure drop fluctuations of periodically fluctuating flow inside the inertia track of the hydraulic engine mount and its resistance. Moreover, to achieve a new model for resistance, the friction factor of fluid under frequency excitation, which is a main cause of discrepancies between simulation and experimental results, has been investigated. Two major findings were explored in previous studies have been used in this research: First, the friction coefficient in oscillatory and reciprocating flow inside a finite length of pipe depends on the kinetic Reynolds number and the dimensionless oscillation amplitude of the fluid; and second, the linear model and the equations of the typical engine mount have been significantly examined. An extensive set of experiments have been conducted using two test apparatuses to provide numerical data. One examined the effect of a pipe’s geometrical parameters such as cross sectional area and roughness on the frequency response of the pressure difference between the entrance and exit of the finite length pipe. The second test apparatus has been employed to validate the equations of pressure drop in the inertia track of an engine mount. Finally, a new model of resistance was implemented in the old version of the prediction program, showing that the frequency responses of dynamic stiffness simulated by this modified prediction program agreed with the experimental results. This new model could be employed to predict the hydraulic engine mount performance in order to create products confirming more closely to customer needs.