Utilizing Spin-Down Transients for Vibration-Based Diagnostics of Resiliently Mounted Machines

This paper presents a vibration measurement and analysis technique for use during a machine’s spin-down procedure. During spin-down, the machine’s operation covers a continuous wide frequency band, from operating speed to standstill, which allows the estimation of the machine’s vibration transfer function (VTF). This transfer function is rich in information for detecting and differentiating not only machinery pathologies but also problems with vibrational mounts. Utilizing a back-electromotive force sensor to infer rotor speed and a single-axis accelerometer for vibration measurements, this technique allows minimally intrusive estimation of a machine’s VTF. Data collected in laboratory and field tests aboard U.S. Navy ships are presented to demonstrate the usefulness of this monitoring technique.