Engineering guide
Unbalance response in shaft–bearing rotor systems
Use this guide to understand how defined unbalance is carried through the shaft–bearing system and what response-domain calculations add to the engineering decision.
Why response matters
A rotor can pass a static or modal screen and still require a response check. The response calculation asks what displacement, orbit or vibration level the selected system produces under a defined excitation at a defined speed.
This is the practical bridge between support-state modelling and operating behaviour.
Inputs that must be controlled
A credible unbalance-response result needs a controlled shaft model, selected support locations, coefficient basis, operating speed, unbalance definition and measurement or reporting convention. If those inputs are vague, the reported peaks are only loosely interpretable.
The selected AURA public case demonstrates this structure by carrying the bearing definition into the shaft and rotor model before time-domain response is evaluated.
What the output should say
Useful outputs include operating point, displacement peaks, axis or orbit information, the definition of the applied unbalance and the relationship of the result to any allowable motion or clearance margin.
The goal is not merely to show that the solver ran, but to show what the result means for the engineering decision.
How response differs from balancing evidence
Response analysis predicts the behaviour of a defined rotor-support system. Balancing evidence evaluates what measured or corrected imbalance results are allowed to prove in the real process. They are related but not identical questions.
One belongs to the modelled machine consequence; the other belongs to release and manufacturing evidence.
Where response fits in the workflow
Response-domain work is especially useful once one support state has been selected and the team needs to understand the consequence of that choice. In AURA this becomes the fourth link after requirement, bearing state and machine layout.
That sequence makes the response result a decision tool rather than an isolated plot.
Apply the guide to one real machine question.
Start with loads, speed, envelope, gas supply and the decision you need.