Coupled Nodes??
Coupled Nodes??
(OP)
Hello.
I am doing an analysis of an electronic chip undergoing thermal cycles. I am using a slice model of the chip and there is a particular boundary condition that I do not know how to apply in ABAQUS.
I want to make sure that a plane that is opposite the symmetry plane to remain parallel to the symmetry plane while the chip is expanding. I understand I can do this by 'coupling' all the nodes on that plane to cause it to remain planar while the plane moving.
I understand in Ansys,you can just simply select those nodes, then select the degree of freedom to be constrained. But I am not sure for Abaqus. I hope someone can help me with this.
Thank you
Regards
Jeremy
I am doing an analysis of an electronic chip undergoing thermal cycles. I am using a slice model of the chip and there is a particular boundary condition that I do not know how to apply in ABAQUS.
I want to make sure that a plane that is opposite the symmetry plane to remain parallel to the symmetry plane while the chip is expanding. I understand I can do this by 'coupling' all the nodes on that plane to cause it to remain planar while the plane moving.
I understand in Ansys,you can just simply select those nodes, then select the degree of freedom to be constrained. But I am not sure for Abaqus. I hope someone can help me with this.
Thank you
Regards
Jeremy





RE: Coupled Nodes??
http://www.eng-tips.com/faqs.cfm?fid=376
http://www.eng-tips.com/faqs.cfm?fid=1083
RE: Coupled Nodes??
I tried both (assuming I am doing it correctly). Equation allows me to run to completion but the results seem weird. But when I tried kinematic coupling constraint, it ran into warnings.
Thank you
RE: Coupled Nodes??
B) How did you write your equation and kinematic coupling constraints?
http://www.eng-tips.com/faqs.cfm?fid=376
http://www.eng-tips.com/faqs.cfm?fid=1083
RE: Coupled Nodes??
As for the kinematic coupling constraints, I created a reference point on a random node on the plane. After which, I selected it as the 'control point' and the plane to be the surface that I want it to remain planar. The constraint is also in the Y direction.
So yah, that was what I did. I did read the documentation before, but I am not sure where I had gone wrong though.
Thank you.
RE: Coupled Nodes??
http://www.eng-tips.com/faqs.cfm?fid=376
http://www.eng-tips.com/faqs.cfm?fid=1083
RE: Coupled Nodes??
Sorry, I didn't come across the term 'poissoning'. What does that mean? Like poisson effect? How do you enable it?
Appreciate much, thank you.
RE: Coupled Nodes??
If so, then I don't see why there should be any difference in the results, unless I am missing something. If you can, you are welcome to upload your INP.
http://www.eng-tips.com/faqs.cfm?fid=376
http://www.eng-tips.com/faqs.cfm?fid=1083
RE: Coupled Nodes??
I have uploaded the input file. I hope you or others are able to help me check if I am missing something as well, will be very grateful for your help.
Much thanks.
RE: Coupled Nodes??
Coming to your INP, my comments below reflect an outsiders' opinion. Everything that you are doing may be right.
Why do you have 400,000+ C3D8R elements? Given the geometry, I would have imagined a few hundred or thousand (tops!) would do the job.
Unless you expect large deformation, strains, rotations, there is no need to have "nlgeom=Yes" in the step definition.
Also, the mesh quality seems a little off the mark. C3D8 elements give you the "best bang for your buck" *if* they are as close to a rectangular geometry as possible. But if these crooked elements are far away from your region of interest, then you have nothing to be concerned about.
http://www.eng-tips.com/faqs.cfm?fid=376
http://www.eng-tips.com/faqs.cfm?fid=1083
RE: Coupled Nodes??
The region of interest is actually the solder. But to be safe and accurate, I created more elements for the rests. Ys, I kind of agree with you that my mesh quality seems a bit off, but that is the best mesh I can produce.
Thanks again for your help
RE: Coupled Nodes??
It does not make physical sense which is why ABAQUS decides to ignore one of the constraints for it to be able to solve the problem. If the solution makes sense, then you can ignore the warning.
http://www.eng-tips.com/faqs.cfm?fid=376
http://www.eng-tips.com/faqs.cfm?fid=1083