Date of Award

12-2006

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Mechanical Engineering

Advisor

Haque, Imtiaz

Abstract

Periodic force variations produced by nonuniform tire/wheel assemblies are known root causes of torsional steering wheel vibrations known as 'nibble'. Previous studies have sought to investigate this issue through modeling or experimentation involving the entire vehicle or specific subsystems, however a direct link between objectively measured tire force variations and the vibration levels perceived by vehicle occupants has yet to be established. Analytical models of a nonuniform tire, double-wishbone suspension system, and rack and pinion steering system are sourced from literature and integrated into a single subsystem-level model validated against experimental data obtained as part of a collaborative effort. The integrated analytical model is used to simulate the nibble vibration on a 2004 Ford F-150 4x4 SuperCrew, revealing that due to the frictional and inertial properties of the steering subsystem, driving at 75 mph produces a 13.8 Hz steering resonance of a subjectively unacceptable magnitude with even modest tire nonuniformity.

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