Gene Vogel
EASA Pump & Vibration Specialist 

When high vibration occurs on a machine at a single frequency and in only one plane, the cause is often a resonant condition. All machines have various natural frequencies. If a machine is “bumped" with sufficient force (not running), it will vibrate at those natural frequencies. Resonance occurs when an exciting force such as 1xRPM, vane pass or other similar force coincides with a natural frequency, resulting in very high vibration at that frequency. Sophisticated techniques such as operating deflection shape (ODS), modal analysis and Bode plots are often used to positively identify resonant conditions. These require dedicated vibration instruments and a well-trained technician. But there are simpler tests that can help identify resonance. 

MEMBERS ONLY CONTENT - LOGIN REQUIRED