When I used switch method in my calculation, I used explicit method and then I changed to implicit method. In the later implicit calculation process, it was seen that the contact didn’t work properly. What was the problem, and how can I avoid this?

In implicit analysis, the constraint approach for FORMING contact is not implemented (this contact is activated when SOFT=4, the first parameter in the optional card A under the card of Forming contact). When switch method is used, the value of SOFT should be default or zero, otherwise, contact difficulty will occur.