Load control Vs. displacement control

[Mohamedsayed]

Hello
For Elastic-perfect plastic material or strain softening material, I notice that if i apply load more than the yield limit, the model diverges, while when i apply load through displacement control, the model converges, although the displacement is big.

So my question is why load control is usually associated with divergence, I guess when the applied load exceed the yield limit and since the material behavior is elastic-perfect plastic or strain softening , the stiffness matrix becomes negative or it might have singularity.

Please correct me if i am wrong.

i have another question, how can i use load control for elastic-perfect plastic or strain softening material, where the load is more than yield limit.

Thanks

 

[IceBreakerSours]

In general, there is plenty of information available regarding this specific topic on the internet. If you are a member of LinkedIn, there was a recent thread covering this in the ABAQUS user group. Bottomline: You should use a Riks (displacement based) solver. Read the documentation for more.

Are you new to this forum? If so, please read these FAQ:

http://www.eng-tips.com/faqs.cfm?fid=376

http://www.eng-tips.com/faqs.cfm?fid=1083

 

[portliner]

You can apply prescribed displacement(s), increasing them by small time-increments. Monitor the resulting reaktion forces and evaluate the solution when the forces reach the desired value(s).

 

[IceBreakerSours]

.. which is what Riks does.

Are you new to this forum? If so, please read these FAQ:

http://www.eng-tips.com/faqs.cfm?fid=376

http://www.eng-tips.com/faqs.cfm?fid=1083

 

[Mohamedsayed]

Thank you So much guys, I will read the manual, but to me knowledge RIKS used only for elastic behavior, right?