henriquegpo
Subscriber

Hello Sean,

Thank you for the comments. I implemented your suggestions one at a time, and the outcomes were the following:

First, changing the contact from asymmetric to symetric resulted only in changes in the plate stress values and profile. The stress in the sphere was still not calculated and has not converged for force.

Through the initial contact information, I noticed that the program controlled pinball radius was already very close to my elements size. The elements are 0.1mm, and the pinball was also 0.1mm for the Asymmetric contact, and recalculated as 0.09mm for the Symmetric contact. I tried making it even bigger in both cases, but none of that changed the results, not even the Number Contacting.

Finally, when I changed the contact detection to Nodal Projected Normal from Contact, the solver did not converger at all, not even with displacement. Error message: "The solver engine was unable to converge on a solution for the nonlinear problem as constrained.". Looking the the solver output text, I found some things that may be useful:

*WARNING*: The default pinball radius may be too small to capture      
 contacting zone under small sliding assumption.  Redefine the pinball  
 radius if necessary.                                                   
 The resulting pinball region                 0.97598E-01
 *WARNING*: Initial penetration is included.
 *** NOTE ***                            CP =       0.516   TIME= 12:03:45
 Min.  Initial gap 3.75099569E-05 was detected between contact element  
 2225 and target element 2284.                                          
 You may move entire target surface by: x= 0, y= 3.75099569E-05, z= 0,  
 to bring it in contact.

 

In the initial 3 substeps where the solution still converged, several messages like this appeared:

THERE IS TOO MUCH PENETRATION AT      4 CONTACT POINTS OF THE 2D CONTACT ELEMENTS
 *** WARNING ***                         CP =       1.750   TIME= 12:03:46
 Convergence has been achieved in spite of large penetration.           
 If this message is repeated frequently, we recommend either increasing 
 penalty stiffness (FKN), or enlarge penetration tolerance(FTOLN).      

 

Then it stopped converging in load step 1, substep 4.

Would you perhaps have some more ideas?

I will do some more tests with the pinball region and also will move the geometry to try to manually close that gap mentioned.

Thanks again,

Henrique