Hello everyone,
I am currently working on a finite-element code for assemblies of bar/trusses undergoing large rigid-body motions. I have some knowledge about standard finite element coding but experience some severe trouble finding information about a rigid-body motion only finite elements (I plan to add small deformations and other features later).
I googled RFEM (Rigid-Finite Element Method) but didn't found any satisfying information.
So, I'll try to keep my questions quite general, but I can make it more precise
* Is there any book or standard method written for this kind of problem (bar assemblies undergoing rigid-body motions). Any suggestion is welcomed.
* What degree of freedom/node choice would be recommended :
-My professor advised 3DOF (2displacements+1rotation) at the center of the bar. And 2 other rotational DOF at the edges of the bar. This seems quite odd to me, I think I might have misunderstood him or that he didn't thought about the problem correctly.
-I found some publications with 4-displacement DOF (2 at the edge of each bar), which seems more appropriate. The method does not seem standard though.
Any thoughts about this ?
Thank you in advance for your help. If you need any precision to understand my problem, feel free to ask me. And sorry if I missed a similar post somewhere in the forum :)
perhaps a corotational analysis will serve your purposes
Perhaps a corotational analysis will serve your purposes in the end. You might start by looking at the following papers I have written on my website.2D trusses http://people.wallawalla.edu/~louie.yaw/Co-rotational_docs/2Dcorot_trus…
3D trusses http://people.wallawalla.edu/~louie.yaw/Co-rotational_docs/3Dcorot_trus…,
Louie
In reply to perhaps a corotational analysis will serve your purposes by yawlou
Thanks for the links, I
Thanks for the links, I already thought about using a co-rotational analysis but the documents I found seemed somewhat obscure to me. Will definitely check this. I think I might go for a multibody system analysis in the end though.
In reply to perhaps a corotational analysis will serve your purposes by yawlou
So I checked out and analyzed
So I checked out and analyzed your document ! I managed to make some program and I think it works about like the one on your 2D Corotational Truss for another project and purpose actually. Works great ;)
However, I still have a problem to use this method for rigid body motions. As I said before, the whole motion is unconstrained which will probably make the stiffness matrix singular. I have seen scientific papers with unconstrained rigid body motions modeled by FE method but I am not sure whether these are scam or not since none of them seems to clarify why their method works with unconstrained motions.
By any chance, did you already model unconstrained rigid body motions with FE methods in the past or do you have any thoughts on this ?
Thanks in advance for your help !