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Differences between CBEAM and CMBEAM

Dear all,

I am building an elastic multi-body dynamic model and I need to model the screws connecting some parts in the model. I plan to model the screws as 1D beam elements. I have seen that I have two options, CBEAM and CMBEAM. The documentation says:

CBEAM: The CBEAM bulk data entry defines a beam element (BEAM) of the structural model.

CMBEAM: Defines a beam element for multi-body dynamics solution sequence without reference to a property entry.

I'm leaning towards CMBEAM more as it specifically states the element is for multi-body dynamics. But I don't quite understand the differences between the two. I have seen CMS models which use CBEAM instead of CMBEAM so it seems it is indeed possible to use CBEAM in an elastic MBD analysis.

I would be grateful for any further information regarding the differences between CBEAM and CMBEAM, as well as which one should be used for an MBD analysis comprising flexbodies.

Best regards,

Deniz Bilgili

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Altair Forum User

Hi,

CMBEAM will be purely used for Multibody analysis using OptiStruct.

Altair Forum User

Hello Prakash,

Thank you for your answer. Though I understand that CMBEAM is specifically designed for MBD analyses, I would like to know some more, even at an abstract level, about the differences between the two. I do not necessarily ask about the mathematical formulation differences between the two, but I'd like to know more about the conceptual differences which would give me a general idea about what they really are. For example, since it is possible to use both CBEAM and CMBEAM for an MBD analysis, what would really differ between two analyses one of which uses CBEAM and the other uses CMBEAM?

That is, of course, if it's possible for you to share with me.

Thank you for your time.

Kind regards

Altair Forum User

Hi,

CBEAM can be reduced within CMS and is visible afterwards in HyperView

CMBEAM is an MBD entity, which cannot be vizualized in HyperView.