Creating the NASTRAN `OUTPUT2' file

  The input file to the interface program is created by the `OUTPUT2' utility module (for a description see NASTRAN User Manual page 5.4-87). This is accomplished by amending the DMAP sequence being used for the analysis by placing an alter in the executive control deck of the NASTRAN input file. The alter is usually located on a line which has a result extraction module (normally the stress extraction module `SDR2') and so the line number to be altered depends on the solution sequence used.

The alter consists of two types of data blocks, the first which define the geometry of the model and must always be present even when appending results to a model which already exists. The second type contain results.

The results data blocks which can currently be processed are:

OES1 Stresses

OES1C Composite Stresses

OEF1 Moments and Forces

OEF1X Moments and Forces (BAR and BEAM results extended to station points)

OEFIT Composite Failure Indices

OEP Element Pressures

OGPFB1 Grid point Force Balance

OGS1 Surface and Volume stresses

ONGRY1 Strain Energy

OPG1 Load Vectors

OPHIG Eigenvectors

OQG1 Forces of single point constraint

OSTR1 Strains

OUGV1 Displacements (also velocities and accelerations if calculated)

The names of these tables may change for some solution sequences (refer to Appendices E and F). Any valid combination of these results tables can be included in the `OUTPUT2' statement.

The result tables are created by NASTRAN depending on what result requests are made by the user in the Case control deck of the NASTRAN input file. The contents of the result tables are affected by the output options selected in the case control deck. For nodal results, e.g. displacements, the option `ALL' must be used.

The user must insure that the file created by the `OUTPUT2' utility is made permanent after the completion of the analysis. This is machine dependant and the user is refered to the NASTRAN Applications manual section 7.6.3.10 for further details.

Examples of the form of the ALTER's for various solution sequences are given in Appendices E and F.

For database solution sequences an alternate method for creating the file is to execute a seperate `DMAP' program after the analysis which will extract the required data blocks from the database and create the 'OUTPUT2' file. NASTRAN does not always store the datablocks under the names recognisied by the interface program and so these datablocks need to be renamed.