FEA code with different tension / compression Young's moduli 2

[maugustyniak]

Hello,

Some time ago I was faced with a Finite Element simulation involving Taramide polymer.
I have found out, that this material has significantly different behavior in tension and compression, due to microscopic effect, not observable however at a macro-scale, so it is NOT an issue of global buckling.
I read as well, that some common materials - like cast iron - may exhibit a similar phenomenom too.

Finally in our project we applied ANSYS and used an uniform Young's modulus in both compression dn tension, verifying, whether this assumption can be considered as conservative. But the problem remains. We use ANSYS, ABAQUS, NX Nastran and Radioss regularly, and I am almost sure these popular and robust codes do not allow such a "taramide-like" option.

Do you know some other code, commercial or not, which supports different Young's moduli in tension and compression?

P.S. The only article on the subject I found dates back to 2001; the Abstract and 1-page preview show it is rather a theoretical introduction, not an example of application.
"A new elasticity and finite element formulation for different Young’s modulus when tension and compression loadings", by Ye Zhi-ming, Yu Huan-ran and Yao Wen-juan.


Marek Augustyniak, Ph.D.
R&D Manager (Structural / EMAG)
DES ART Gdynia
Poland

 

[sdra2]

Hello

I don't know anything about taramide at all, but I do know that ANSYS has a cast iron material model that allows the user to input different stress-strain curves for tension and compression. Page 172-182 of the attached link gives some info on this. Perhaps it can be adapted to your needs if you have sufficient material data?

Cheers

 

[crisb]

Most codes allow a nonlinear stress strain curve, possibly as a user defined stress strain curve. I expect this is possible in most of the codes you have quoted.

 

[sdra2]

Oops, almost forgot - I think I recall that the first data points that you enter for both the tensile and compressive curves have to define an equal Young's modulus in effect, but you can set this first part of the curve to be very near the origin and then do whatever you wish for the rest. Again, I'm not sure if this can be adapted for taramide or not but it might be worth a look.

Cheers

 

[kellnerp]

Look for non-linear elastic options in whatever code you are using. You probably want to take into account temperature in setting your curves too.

TOP
CSWP, BSSE

http://www.engtran.com

http://www.niswug.org

"Node news is good news."

 

[xy1983]

Hi,
Do you solve you problem?I also meet this problem? Can you tell me the method how to solve it?
Thank you.

 

[jackwangsx]

sdra2:
I follow your advisement to solve a four-point bending problem.
I set the first point in compressive region very close to the origin and set the second point so as the second slope is half of the young's modulus.
The result is not as I expect.
The result is almost has no different with the one which has same tensile and compressive modulus equal to half of the young's modulus.
Attached .db file FYR.