====== Modeling Limitations and Suggestions ======

===== Node =====

The user is limited to node number of 6 digit positive integers. (1-999999). The user may use any number within that range to define a node. The node number do not have start at 1 or be consecutively defined (no gaps), but either of situations exist it may cause extended simulation durations.

All nodes in ACS SASSI have 6 degrees of freedom. Node that are only connected to solids will not have rotations. In theory these unfixed rotations should not affect the solution, but the unfixed rotations can cause instability in some solvers on larger models. [[com:FIXROT]] will detect where a rotation should be fixed and apply the right constraint to the node. Also the removal of these rotations from the matrices make the overall problem smaller and faster to solve.
    
===== Elements =====

The user is limited to element number of 5 digit positive integers. (1-99999) per group. Element numbering must start at 1 and be consecutive. If a model has either of these issues [[SASSI:ACS-SASSI User Interface]] will throw an error and not allow a [[file:.hou]] file to be written for simulation. The user can use [[com:ECOMPR]] to compress the element numbers in the problem groups to fix this error.