Analyzing Gearbox Degradation Using Time-Frequency
Signature Analysis
Lin
Liu, Zhuang Li, Suri Ganeriwala
SpectraQuest Inc., 8201 Hermitage Road, Richmond, VA 23228
Published: Mar 2006
Abstract
In this
work, vibration signature caused by gear tooth seeded fault is
studied in the time and frequency domains. The experiment was
conducted on a Machinery Fault SimulatorTM(MFS). The
pinion gear in the gearbox was intentionally faulted with increasing
severities, and a vibration signal was collected for each case. The
signal was analyzed in a time and frequency domain. The results
indicated that the vibration signature of a faulted bevel gear tooth
is a pulse in time domain. Because of this impulse signal, strong
sidebands arise in the spectrum around the mesh frequency.
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Introduction
The experiment is conducted on a Machinery Fault
Simulator TM (MFS). The vibration data was
collected by a tri-axial accelerometer installed on the top of the
gearbox. The frequency limit was set to 5 KHz during data
acquisition. During the test, the motor speed was kept at 1000 RPM
and the brake loader was set to 2.5. First, the baseline of the
gearbox vibration data is collected. Then the gearbox is
disassembled and the pinion gear is taken out. The surface of one of
the pinion’s teeth on the meshing side is milled using a drill mill.
After the damage is done to the tooth, the pinion gear is put back
into the gearbox. Vibration data is collected again under the same
running conditions (speed and load) as before. This process is
repeated four more times with additional damage applied to the same
pinion tooth for each case scenario. The five damage severities are
denoted as Severity Level 1 to Level 5, from the least to the most.
Fig 1: Baseline Vibration Signal Spectrum around
Mesh Frequency Component
Fig 2: Vibration Signal Spectrum (Damage
Severity Level 5)-Spectrum around Mesh Frequency Component
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