Export NASTRAN File: Load and Freedom Cases

Description

Load Cases

For each load case, Straus7 posts the following load case global data:

If a non-zero linear acceleration has been defined, Straus7 posts a GRAV entry in large-field format. This entry contains the load case ID, a scale factor of 1.0, and acceleration components (N1-N3).
If a non-zero angular velocity has been defined, Straus7 posts an RFORCE entry in large-field format. This entry contains the load case ID, a scale factor A of 1.0, an angular velocity vector (R1-R3), and a node ID defining the origin. This node is specially created at the rotation origin if a non-zero angular velocity or acceleration has been defined.
If a non-zero angular acceleration has been defined, Straus7 posts an RFORCE entry in large-field format. This entry contains the load case ID, a scale factor RACC of 1.0, an angular acceleration vector (R1-R3), and a node ID defining the origin of rotation. This node is specially created at the rotation origin if a non-zero angular velocity or acceleration has been defined.
A TEMPD entry is always posted. This entry contains the load case ID, and the default temperature for this load case.

Freedom Cases

For each freedom case, Straus7 checks to see if global restraints have been defined. If so, an SPC1 entry is posted. This entry contains the freedom case ID, the components that have been fixed, and the entire node point range (using the alternative "THRU" format).

A GRDSET entry cannot be used to define global freedom conditions, because GRDSET is not case-specific.

Combined Loading

Straus7 and NASTRAN support load cases that specify combined loading in different ways. NASTRAN does not allow acceleration based loads, simple loads (force, pressure, etc.) and thermal loads to be combined in a single load set. As a result, each Straus7 load case may be broken down into three separate NASTRAN load sets which are subsequently re-combined into a single NASTRAN load case using a LOAD statement.