Rigid-body only FEM

[dvisacker]

Hi everyone,

I am currently trying to program a MATLAB FEA code that would only take into account large rigid body deformations (no strains, no stress, I might implement this later) for bar linkages (will also head toward beams and more complicated elements later) and the trouble I have is finding the adapted theory for this.

All the FEM documentation I read only mentions rigid-body modes as something you want to avoid (unconstrained model etc.). I found some scientific papers treating this subject but the method they suggest does not seem standard to me ?

-Does anyone have any experience in this kind of problems or have any suggestion for a good book/website about this topic ? I hope this post is not too vague, feel free to ask for more details if needed

Thanks to all of you in advance for your help,

 

[GregLocock]

"All the FEM documentation I read only mentions rigid-body modes as something you want to avoid" Sort of, but not really. For instance if you were running durability on the body of a car with inputs up to 80 Hz you might model various things hanging off it as rigid bodies, and they might have RBMs as low as 6 Hz.

It sounds like you are trying to code a multi body dynamics simulation, it's not really FEM tho.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

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[rb1957]

you're googling in all the wrong areas ...
"rigid body motion" refers to constraining a FEM in space so the FEA doesn't spin out of control.

Whilst your idea is "rigid body", in that your mechanical system components are not straining; really you're looking for mechanical system simulation (like "adams").

another day in paradise, or is paradise one day closer ?

 

[stressebookllc]

Rigid body motion in simple term is just that. A part or a system moves unconstrained, either translates or rotates.
If you simply want to simulate the movement of links in a system, then it looks like rb1957 hit the nail on the spot.
May multi body dynamics simulation is the right phrase?

http://www.stressebook.com

Stressing Stresslessly!

 

[dvisacker]

Indeed, I just googled around and multi-body dynamics seem to be more adapted. Thank you for the advice !

 

[stressebookllc]

A blog post, maybe you will find some use for it:

http://www.stressebook.com/rigid-body-mode/

http://www.stressebook.com

Stressing Stresslessly!