Nonlinear spring link

Hello,

I would like to model two timbers connected with a nail whilst taking the system past critical load (large deformations?). The intention was to model:

1. the timbers as 3D solids with contact elements to prevent interpenetration and allow separation
2. the nail as line element with properties obtained from test. I have full load-slip diagram (that is obviously non linear)

The contact part is fine.
The variable stiffness spring is not. Currently I am trying to use barre element and nonlinear material (load-slip diagram converted to stress-strain). Ideally I would like to refrain from using the real nail geometry/section and assume only shear and tension on the nail (no compression - this shall be transferred by contact)

What is the CA way of modelling this?

My apologies to bug you with this, I have been looking for an answer in the CA docs for quite some time. Could you please point me to the right direction?

Many thanks
Michal

Hello,

recently I stumblede across a paper where the modelling of wooden structures which are connected with nails is described.
They used Code_Aster, so this might help you:
www.naun.org/main/NAUN/energyenvironment/2011-101.pdf

Hope this helps!

Best regards,
Richard

Hello Richard,
thank you for the hint and link. The approach they took was to use DIS_ECRO_CINE which only simulates bi-linear behavior I think rather than curve.
Any other suggestions / example?
Michal

I'm sorry,
I am not really an expert in dicrete element modelling with Code-Aster, perhaps you should ask that question directly in the Code-Aster forum: www.code-aster.org/forum2/

If you are using CAELinux, you could also try CalCuliX, which seems to have nonlinear spring elements defined directly as you want: web.mit.edu/calculix_v2.7/CalculiX/ccx_2.7/doc/ccx/node242.html

I'm not sure, but I think you could also model a nonlinear spring on Code-Aster by couple multiple springs with different stiffnesses.

Best regards,
Richard