MASS21 - use with or without the rotary inertia?

[Vitkacy1989]

Hi Folks,

I have a question on MASS21 keyoption (3).
We can decide whether or not our mass element should include rotary inertia.

So far I always thought that rotaty inertia is always a-must since it lets knows the Solver how unmodelled part behaves under certain acceleration.

My question is, could you shortly explain when mass without rotary inertia is useful?

 

[Shu Jiang PEng SE]

You do not need to consider rotary inertia whenever the support is coincident with the (equipment (mass) rotation center.

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J&J Structural Consulting Inc.
Structural design, analysis, inspection, drawing review and stamping, and connection design

 

[scheah]

could you shortly explain when mass without rotary inertia is useful?

Static analysis does not require rotary inertia to be useful.

Kind regards,
Jason