Learning Forum

[Chris Quan]

Yes, it is true that an external gap is required in contact calculations between IJK-based Lagrange grids.

If there is no such gap present, user can convert the IJK-based (structured) Lagranage grids to unstructured grids (mesh) and then use Trajectory type of contact. Trajectory contact doesn't require an external gap.

Among the conversion options:

Delete converted IJK regions: Deletes the structured IJK Parts that have been converted to unstructured grids after the conversion process. 

Merge connected IJK Parts into single Unstructured Part: Merges connected IJK Parts into a single Part. This simplifies the model and can also improve performance because there will be fewer Joins in the model. For some applications, you may not wish to merge the IJK Parts in this way. Clearing this option will result in no change in the Parts defined in the model.

Merge joined IJK nodes into single unstructured node: All joined nodes are merged into a single unstructured node during the conversion process. In some cases, for example if you have pinned joins, you may not wish to do this.