If an imbalance should be only considered as a force without adding mass to the shaft, this element has to be used. The imbalance force will be regarded as a harmonic force and calculated in the same way as with an eccentric mass, that is: , but the inertia and the natural frequencies of the shaft will remain unaffected.
The imbalance will only affect the results for the harmonic response. Bearing life, contact stress or safety factors for shaft strength will not change.
Setting the option Consider dynamic loads in static equlibrium will lead to a change of bearing life or safety factors, but this is an approximation only.