Date of Award


Degree Name

Master of Science in Engineering


Mechanical and Aerospace Engineering


Mechanical and Aeronautical Engineering

First Advisor

Dr. Koorosh Naghshineh

Second Advisor

Dr. Jim Kamman

Third Advisor

Dr. Philip Guichelaar

Access Setting

Masters Thesis-Open Access


During the development process of heavy-duty truck transmissions, specific gear designs (geometries) are created to meet load requirements and ratio coverage. Few tools are available to investigate the noise generating potential of these transmissions early in the design stages. This research describes the development and application of a software program that predicts transmission countershaft vibration modes. From simple gear and shaft geometries, the program calculates gear mesh forces and bearing forces then construct the system of equations to compute the shaft vibration modes. Because of the way the input data was structured, this software tool can also be used to perform basic analysis on gear tooth interaction and compare two different transmission models for noise and vibration diagnostics. The methods presented in this research can be applied to a variety of simply supported shafts, which make it useful for many different transmission models. Noise and vibration data from two transmissions are presented and compared to the predictions from the program. It was shown that the shaft mode frequencies correspond reasonably well with the frequencies measured in the noise data and that the other diagnostics features in the program will be useful when analyzing a complete transmission system.