Candidate: Min Lu

Degree of: Doctor of Philosophy

Department: Mechanical and Aeronautical Engineering

Title: Study of Automotive Hydromount Mechanism

Committee:
Dr. Judah Ari-Gur , Chair
Dr. James Kamman
Dr. Iskender Sahin
Dr. Frank Severance

Date: Friday, March 9, 2001 10:00 a.m. - 1:00 p.m.
3014 Kohrman

Abstract:
The hydromount mechanism is studied. It was determined that the dynamic characteristics of the hydromounts are related to the rubber static stiffness, rubber damping coefficient, volumetric stiffness, and effectiveness of the oscillating fluid in the inertia track. At high frequencies the motion of the fluid in the inertia track diminishes so that its effect is negligible and may be ignored. It is also concluded that the rubber damping has a minimal effect on the hydromount dynamic properties and may be neglected. The maximum loss angle, which corresponds to the maximum damping coefficient of the hydromount, occurs near the inertia track fluid resonant frequency. The degree of this proximity depends on the damping ratio and dynamic stiffness ratio. Through a parametric study it was found that a higher rubber static stiffness results in a higher peak dynamic stiffness, but at a lower peak loss angle. Increasing the volumetric stiffness, fluid density, or inertia track cross-sectional area and length results in an increase of the peak dynamic stiffness and peak loss angle. A larger equivalent piston area results in lower peak dynamic stiffness and peak loss angle. The inertia track damping coefficient, generated by the
(over)
oscillating fluid between chambers, is a function of the frequency along with other variables: inertia track equivalent radius, length, fluid density and viscosity. The predicted dynamic characteristics of a variety of hydromounts match reasonably well with test results.

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