I am running a 2D contact problem with node to surface behaviour, but I get this warnings I do not understand. I know they are warnings but would like to undrstand them and try to delete them if possible.
Can you help me?
*WARNING reading *SURFACE BEHAVIOR: hard
behavior is by default reduced to
linear behavior
*WARNING reading *SURFACE BEHAVIOR. Card image:
*SURFACEBEHAVIOR,PRESSURE-OVERCLOSURE=HARD
*WARNING reading *SURFACE BEHAVIOR: K must
be strictly positive
the following default will be used: 10300000.000000000
the user is advised to analyze the results
carefully
*INFO reading *SURFACE BEHAVIOR: the tension
value at large clearances
(only relevant for node-to-surface contact)
must be strictly positive
the following default will be used: 2.9428571428571431
the user is advised to analyze the results
carefully
This is just what CalculiX does internally when you use hard contact.
This is automatically selected contact stiffness when using hard contact.
Another default value.
Here’s an explanation from the CalculiX User’s Manual about all of that:
Hard pressure-overclosure behavior is internally reduced to linear pressure-overclosure behavior with the default constants.
The linear pressure-overclosure behavior simulates a linear relationship between the pressure and the overclosure. At zero overclosure the pressure is zero as well. For node-to face penalty contact the user should specify the slope of the pressure-overclosure curve (usually 5 to 50 times the typical Young’s modulus of the adjacent materials; the default is the first elastic constant of the first encountered material in the input deck multiplied by 50) and the tension value for large clearances σ∞ (should be small, typically 0.25 % of the maximum stress expected; the default is the first elastic constant of the first encountered material in the input deck divided by 70,000).
Thank so much @Calc_em! I missed that from the user guide!
In that case it is just a warning to take into account, but I cannot do anything from my input file to delete these warnings!
Thanks!
Right thank you.
In the following line to this text:
This is written:
In case of mortar contact true hard behavior can be simulated by omiting the *SURFACE BEHAVIOR card within the *SURFACE INTERACTION card.
Is there anyway where I can read what is mortar contact true?? What I want to check is what it changes from what I do in abaqus with a hard surface behaviour and what i am doing in calculix. I would like both to be the most similar.
This type of contact is described in the section 6.7.8 Face-to-Face Mortar Contact (page 244). It uses Lagrange multipliers while the standard node-to-face or face-to-face contact is of penalty type.
interesting in computational times and convergences please reported, as i know Abaqus did not have advanced Mortar contact type, Ansys also but LS Dyna has.
