An operational deflection shape (ODS) is a visual representation of how a structure - with a known or unknown set of structural resonances and modes - moves under the action of one or more forcing frequencies during normal operation. It is an effective tool for diagnosing machine faults that cannot be detected using measurements taken during a standard vibration survey. Therefore it is commonly undertaken on problem machines as a root cause analysis tool.

 

The technique can be used to diagnose machine faults such as misalignment, cocked bearings, excessive structural movement, soft foot, structural resonance and many other phase-related conditions. ODS differs from modal analysis in that it provides the actual structural deflection under load, while modal analysis is carried out under static unloaded conditions and provides the resonant frequencies and modes which are inherent properties of the structure. The ODS is therefore a function of the forcing frequencies applied and the vibration characteristics of the structure. It shows the actual structural deflections during operation.

ODS

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PDS Condition Monitoring Services Pty. Ltd.

ODS showed high deflections of the winder gearbox at the input stage.