When rupture is modeled and elements are expected to fail, it is important to deal with failed elements defined either as a main segment, or as secondary nodes.

When an element is deleted, its corresponding segment is still taken into account and its nodes are still considered for contact. This behavior can lead to a huge error, as deleted elements have no stiffness; therefore, it is recommended to set the flag Idel to 2 when failure is expected. This flag will remove any failed element from the main surface and corresponding nodes will be removed from the secondary nodes list.
Note: The Idel flag exists as of Radioss V5.1. For older versions, refer to /DELINT/ON.