Import NASTRAN File: Bulk Data

Description

The following topics describe the entries that Strand7 imports.

Creating new load cases and freedom cases

Load cases and freedom cases are created in Strand7 whenever a bulk data entry references a case that does not already exist. New cases are labelled "NASTRAN Case N", where N is the set ID specified by the entry.

For example, if bulk data references a load case 3, Strand7 checks for the existence of load case named "NASTRAN Case 3". If it cannot be found, a new load case with this name is created. Strand7 does not simply use the third entry in the load case list.

What if there is more than one bulk data entry referencing a given element?

Attributes are usually applied in an additive manner. For example, if multiple FORCE entries are defined for the same node (say +100N, +300N and -600N), the total force on that node is the sum of the individual forces (-200N).

Multiple bulk data entries are required when NASTRAN is not able to apply the desired attribute with a single entry. For example, to apply a concentrated beam force, NASTRAN requires a separate PLOAD1 for each non-zero component. Strand7 will superimpose these entries into a single beam concentrated force attribute. Additionally, when NASTRAN needs to give a node multiple fixed displacements of different amounts in different directions, multiple SPC entries are written out for that node. These entries are collected and superimposed by Strand7 into a single node restraint attribute.