Moments and Forces output of Flexible bodies is zero?

Hi, Everyone.

I met a problem of outputting responses of a flexible body.

I just use a cantilever beam as a flexible body in ADAMS, and applying a moment load at one side, the 'total force on point' and 'total torque on point' output of mass center marker are all Zero. I checked the displacement is correct, but have no idea about the forces and moments.

Does anybody know the problem, I am a beginner of ADAMS and would be really appreciated for your kind help. Thank you very much!

Shuai

0 jpatterson over 7 years ago

Did you attach your cantilever to ground? What are the reactions there...???
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0 shuai.wang over 7 years ago

Thanks for your answering. I attached cantilever to the ground with a fixed joint.

The reactions on the joint are normal and counteracted with the load. But internal force along the cantilever are all zero.
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0 jpatterson over 7 years ago

This is the behavior I would expect. I'm pretty sure ADAMS is only going to report forces/moments where you attach a constraint or force element...
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0 shuai.wang over 7 years ago

Thank you, Jpatterson. But is there any way of outputting the forces/moments at specific points on the flexible body?
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0 jpatterson over 7 years ago

Not that I know of. I'm curious why you want them...???
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0 shuai.wang over 7 years ago

Actually, I have measurement strain data of a Wind turbine drivetrain shaft at specific points. I want to compare the Adams simulation with the measurement. Cantilever model is a test.

I heard that Admas can report the strain and stress on a flexible body, maybe I can use them instead of using moments.
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0 jpatterson over 7 years ago

I have not done it, but yes, I believe you can recover stress/strain from a flex body...
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0 jozef.bucha over 7 years ago

Yes you can report strain and stresses in flexible body with durability plugin. Or also you can use FE_part for modeling shaft, then in postprocessor you can measure force and moment in every node of FE_part. You will find those results in post processor under results sets.

Jozef
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0 Jesper Slattengren over 7 years ago

The old and traditional way to get forces along a beam, is to split the part in several flexible parts and connect them with fixed joints. Then you can get the reaction forces at those joints.

But one flex part with stress and strain information is better, unless your element behaves non-linear. The MNF is linear only. Then an FE-part or multiple MNF's connected is better.
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0 jozef.bucha over 7 years ago

Is there any reason for modeling beams with discrete flexible link and not with FE_part? Or is discrete flexible link "obsolete"?
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