Date of Award

4-2011

Degree Name

Master of Science in Engineering

Department

Mechanical and Aerospace Engineering

Department

Mechanical and Aeronautical Engineering

First Advisor

Dr. Judah Ari-Gur

Second Advisor

Dr. Koorosh Naghshineh

Third Advisor

Dr. James Kamman

Access Setting

Masters Thesis-Open Access

Abstract

Gearbox noise emitted from vehicles has become of particular importance to manufacturers due to the significant reduction of engine and masking noises in most modem designs. The reduction of gearbox rattle was the subject of this research using Romax Designer. Both drive and neutral loading conditions were considered for a parametric study of the influence of altering input torque fluctuation, backlash between gears, component rigidities and driveline inertia. Next, an external enclosure was added, where its effect was studied by altering the wall thickness, material properties and fixed boundary positions. Finally, results obtained from Romax Designer for a physical gearbox casing were verified by comparison with experimental results and finite element analysis. The casing was dimensioned using a white light scanner, and tested for its modal characteristics with accelerometer readings taken during hammer tests. Furthermore, gearbox rattle analysis for the three computer simulated models highlighted the importance of driveline resonances in determining increases in drive rattle. Neutral loading conditions, on the other hand, were found to be sensitive to torque fluctuations and driveline inertias. Analysis of the gearboxes with an external casing exhibited significant variation in rattle noise with a sufficiently flexible enclosure. This study provides an outline for designing a complete gearbox for reductions in rattle.

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