Prediction of high-speed shaft natural frequencies employing harmonic excitation

A shaft and bearing system was developed with natural frequencies in the range of 8,000 to 60,000 rpm for the purpose of determining the practicality of low-speed harmonic excitation of high-speed natural frequencies. The analytical development and analysis utilized SPAR, a finite element program, and a bearing stiffness program to determine frequencies for the first through fourth harmonics of natural frequencies under 60,000 rpm. A misaligned flexible disc coupling was used to input a forcing function with a frequency of N times the running speed and thereby excite the natural frequencies in the Nth harmonic at the running speed. Most of the analytical results had corresponding experimental results; however, many increased vibration levels did not correlate with analytical results. Four frequency response plots are presented. A comparison of these plots and analytical results are presented in the form of a Campbell diagram. Although the experimental results are not supportive enough to be conclusive, they do indicate that low-speed harmonic excitation may be a method of predicting high-speed natural frequencies. Major difficulties were encountered in the experimental program which are described, and some alternative investigations are proposed.

Name thesis:degree_name

M.S.

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Mechanical Engineering

Department dc:contributor.department

Mechanical Engineering

Grantor dc:publisher

Virginia Polytechnic Institute and State University

Year dc:date.issued

1983

Author dc:creator

• Lehmann, Katherine Jeanne

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Language dc:language.iso

en

Handle dc:identifier.uri

http://hdl.handle.net/10919/105996

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/105996