Date of Award


Degree Type


Degree Name

Master of Science (MS)



First Advisor

Nancy L. Denton

Committee Chair

Nancy L. Denton

Committee Member 1

Richard M. French

Committee Member 2

Haiyan H. Zhang


High frequency acceleration enveloping is one of many tools that vibration analysts have at their disposal for the diagnosis of bearing faults in rotating machinery. This technique is believed to facilitate very early detection of potential failures by detecting low amplitude repetitive impacts in frequency ranges above conventional condition monitoring. One traditional enveloping method uses a mathematical operation known as the Hilbert transform along with other signal processing procedures such as band-pass filtering and full-wave rectification. For comparison, another method uses a proprietary algorithm included in National Instruments’ LabVIEWTM add-on package: Sound and Measurement Suite. Enveloping’s inherent problem with noise introduction is also addressed herein. A controlled, three-stage fault was induced and diagnosed utilizing both acceleration enveloping methods and traditional fast Fourier transformation (FFT) described herein. A performance assessment of the enveloping process with respect to FFT as well as the performance between individual enveloping methods is presented. In summary, several high frequency acceleration enveloping methods exist that can be effective tools in detection of bearing faults earlier than FFT alone.