Is it possible to allow separation/gap between elements within one part?

Yes, it is allowed to have separation between elements within one part. During the initialization process, LSDYNA will try to connect those elements internally. For most of the situations, this process work perfectly without any problem. However, for some cases, LSDYNA will report error message or warning message.

Suggestions: It is suggested that the elements in each part should be connected, and make sure that there is no separation.