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How to add unbalanced masses to a shaft?

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Dear all,

I am working on the COMSOL case "Whirling of Uniform Shaft Under Gravity" (URL:https://www.comsol.com/model/whirling-of-uniform-shaft-under-gravity-43541).

I would like to add unbalanced masses to the shaft to see the effect on the behavior of the shaft.

I do not want to change the structure of the rotor. How can I add a tiny unbalanced mass to the shaft without changing the shaft structure?

Many thanks in advance.


2 Replies Last Post Feb 29, 2024, 7:00 a.m. EST
Frederik Wagner COMSOL Employee

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Posted: 9 months ago Feb 29, 2024, 6:59 a.m. EST
Updated: 9 months ago Feb 29, 2024, 7:00 a.m. EST

I would suggest that you add the unbalance force directly as a co-rotating point load, e.g. , where , , and are the unbalance mass, eccentricity and rotational speed, respectively.

Frederik Wagner

COMSOL

I would suggest that you add the unbalance force directly as a co-rotating point load, e.g. F_y = m\,e\,\omega^2, where m, e, and \omega are the unbalance mass, eccentricity and rotational speed, respectively. Frederik Wagner COMSOL

Henrik Sönnerlind COMSOL Employee

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Posted: 9 months ago Feb 29, 2024, 7:00 a.m. EST
Updated: 9 months ago Feb 29, 2024, 7:04 a.m. EST

Alternatively, you could add a Disk feature, having a radial offset and zero moment of inertia.

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Henrik Sönnerlind
COMSOL
Alternatively, you could add a *Disk* feature, having a radial offset and zero moment of inertia.

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