Operational Deflection Shape

Operational Deflection Shape (ODS) models are an excellent technique for observing real-world behaviour of a system and establishing how the equipment behaves as a result of forced vibrations. This differs from dynamic modelling which simulates behaviour. The resulting ODS is the actual measured machine response and so contains components of both the forced and resonant vibration.

ODS analysis is a powerful modal testing technique to help visualise the motion associated with vibration.  A representative model of the object is created and then its motion is driven by sensor measurements.  The vibration measurements are recorded from various points across the object’s structure known as degrees of freedom (DOF).  Measurements are then made for the range of running conditions and excitations with which the machinery typically operates.  With the measurements applied to the model it is then possible to animate the system to view how the machines moves.  Animations can not only be made of the time domain so that problems during specific events can be viewed (excessive movement during start-up for example), but also of the frequency domain which can be vital for seeing how the machinery response to primary running speeds and for identify resonant behaviour.

  • Uses input from real-world sensors and animations represent these real-world forced vibrations
  • Absolute dynamic behaviour of a machine and/or structure
  • Time domain response of typical running and start and stop
  • Frequency or spectral ODS to view specific frequencies and modal shapes
  • Visualise the relative motion of system components
  • Highlight excessive flex or decoupling