As its name suggests Operational Deflection Shape analysis shows the vibration pattern experienced during normal operational condition. This is different to other structural vibration tests such as impact hammer tests, bump tests or shaker tests which require a more controlled excitation force and are used to determine specific characteristics of the structure under test, such as natural or resonant frequencies.
Picture the scenario; you have captured some noise & vibration data from a rotating machine. Typically, this might be noise in a vehicle cabin, but could have been anything from…
By combining a speed signal with a data signal and using the Short Time FFT algorithm (Hopping FFT), it is possible to extract order data directly as a function of time (Orders from Hopping FFT) rather than as a function of speed (Waterfall). This is very useful when analyzing a complete operational cycle which includes run ups, rundowns and periods at operational speeds.
