Hi @curator23,

this always depends on which contact you are using.

• Penalty-contact implies penetration of the contact \rightarrow increasing the penalty coeff. will decrease penetration

• Augmented Lagrange contact “augments” the contact force calculation with a variable \lambda that makes the method less sensitive to the contact stiffness

Both have pros and cons:

**Penalty**:

- Good convergence behaviour
- Useful for any type of contact behaviour

**Hint: Penalty coeff. should be ~5-50 times as high as the materials Young’s Modulus**

**Augmented Lagrange:**

- Bad convergence (especially when friction is activated)
- No contact penetration
- Contact detection at integration points

Then there is also a tool that you can use in your contact definition called fictitious clearance.

Explanation by @rszoeke:

When adding a Fictitious Clearance to a contact surface, we add a layer of a fictitious material (with no additional stiffness) with the defined clearance as thickness. On an algorithmic point of view, when it comes down to compute the (signed) contact distance, the solver removes from the actual geometrical distance the fictitious clearance and the result will be used to evaluate the contact state (open/closed) and the contact forces.

So, if your geometry originally has a gap of 2mm and you apply a fictitious clearance of 1mm, the solver would compute a remaining gap of 1mm. After moving one part for 1mm the contact will become active and contact forces will start acting. Using an exact contact algorithm (Lagrangian), the gap will never be smaller than 1mm.

Furthermore you used bonded contact which is the default option for contact.

@afischer described the function of this option:

The solver does not test on contact faces or even interpenetration except if you define physical contacts for those face pairs. If you define a bonded contact, the nodes of the slave surface that should be bonded to the master surface are calculated via a maximum distance (taking the master face element normal into account).

You can define this distance manually by setting the positional tolerance value for the bonded contact

You can play with those options and see what impact they have on your simulation.

This might be a good example to see how @ahmedhussain18 set a tolerance value for a bonded contact:

https://www.simscale.com/projects/ahmedhussain18/bolt_connection/

If you need more help or encounter any problems, feel free to ask.

Cheers!