This is a standard gap element defined between two nodes. The clearance ![]() of
the gap and its direction
 of
the gap and its direction 
![]() are defined by using the
*GAP card. Let the
displacement vector of the first node of the GAPUNI element be
 are defined by using the
*GAP card. Let the
displacement vector of the first node of the GAPUNI element be 
![]() and
the displacement vector of the second node
 and
the displacement vector of the second node 
![]() . Then, the gap
condition is defined by (Figure 69):
. Then, the gap
condition is defined by (Figure 69):
| (9) |