Missing follower force stiffness term in Step 44

[Yiliang Wang]

Hi Wolfgang,

I am studying the code in Step-44. In the benchmark model, it looks like a follower load is applied. Since the the normal direction and the area of the surface which is under pressed is evolving, shouldn't an extra term induced by the follower force be added into the total stiffness matrix in element level? If that term is ignored, I guess the convergence rate will be affected. I am not if the accuracy of the results will also be affected if that term is ignored.

Best,

Yiliang

[Wolfgang Bangerth]

Yiliang:
I'm the wrong person to ask this question, not knowing much about
large-deformation modeling and not having written the program. But perhaps
someone else knows an answer to your question.

Best
W.

--
------------------------------------------------------------------------
Wolfgang Bangerth email: bang...@colostate.edu
www: http://www.math.colostate.edu/~bangerth/

[Jean-Paul Pelteret]

Hi Yiliang,

In the benchmark model, it looks like a follower load is applied

No, this isn't the case. The paper that this numerical example for this tutorial is based on defines the pressure as being applied on the reference configuration, and so neither the normal nor area upon which it is applied evolve (even though the load itself is increased over several load steps). I can only suggest that one look at the paper to confirm the setup:

S. Reese, P. Wriggers, B.D. Reddy (2000), A new locking-free brick element technique for large deformation problems in elasticity, Computers and Structures , 75 , 291-304. DOI: 10.1016/S0045-7949(99)00137-6

But you are right in that one would require a (non-symmetric) linearisation term to compute a consistent tangent matrix if there was a follower load.

I hope that this helps.

Best,

Jean-Paul

--
The deal.II project is located at http://www.dealii.org/
For mailing list/forum options, see https://groups.google.com/d/forum/dealii?hl=en
---
You received this message because you are subscribed to the Google Groups "deal.II User Group" group.
To unsubscribe from this group and stop receiving emails from it, send an email to dealii+un...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/dealii/b5121204-6a5d-4b02-8139-1301e63939c9%40colostate.edu.

[Yiliang Wang]

Hi Jean,

Thanks for your reply. It answered my question. I appreciate your effort and time.

Best,

Yiliang Wang

To view this discussion visit https://groups.google.com/d/msgid/dealii/CAMvdQMA0NPKhfE1ZLZ29T20%2BZgYs3hk8rzBrmrpnKWOZRO_qpA%40mail.gmail.com.