flexprep

Nastran Bulk Data File > H3D

<mode_type_option>

Specifies the method of computing mode types. Available options are:

• ‘CB’ (Craig-Bampton)
• ‘CC’ (CRAIG_CHANG)
• ‘FR’ (FREQUENCY- RESPONSE)
• ‘FF’ (FREE-FREE).

‘CBX’ (Craig-Bampton) is used when all the OptiStruct data has been generated in the same directory and needs to be processed and put together into an H3D file.

<+interface_node_list>

The set of interface nodes. Use the ‘+’ symbol to combine different interface nodes or use ‘:’ to denote a range.

[upper_freq [HZ]]

When Hz is specified, denotes the upper frequency. Otherwise, it specifies the number of eigen modes.

[-<units>]

Specifies the units of the original Nastran model. See the Unit Options below.

[-<stress>]

If specified, stress information is generated by OptiStruct.

-ospath:<DEFAULT|directory>

Specifies the location of OptiStruct. If DEFAULT is specified, the current installation of OptiStruct will be used.

If it is a directory, the OptiStruct installation located in that directory will be used.

Nastran Punch File >> H3D

[-<units>]

Specifies the units of the original Nastran punch file. See the Unit Options below.

Adams MNF >> H3D

[invar_option]

List of invariant options that should be moved/generated from the MNF file to the H3D file. This argument is specified with a total of nine true and false.

[-<NO_UNIT_CONV>]

If specified, keeps the MNF model’s units. Do not convert to H3D units.

H3D >> H3D

[-<mirror_option>]

Specifies the plane about which to mirror the H3D model. Available options are:

• MIRROR_XY
• MIRROR_XZ
• MIRROR_YZ

H3D >> Adams MTX

[invar_option]

List of invariant options that should be moved/generated from the H3D file to the MTX file. This argument is specified with a total of nine true and false.

[+node_list]

The set of interface nodes. Use the ‘+’ symbol to combine different interface nodes or use ‘:’ to denote a range.

[+mode_list]

The list of modes to include in the MTX file. Use the ‘+’ symbol to combine different interface nodes or use ‘:’ to denote a range.

[-<units>]

Specifies units for the MBD solver. See Unit Options below.

[-<mirror_option>]

Specifies the plane about which to mirror the H3D model about. Available options are:

• MIRROR_XY
• MIRROR_XZ
• MIRROR_YZ

H3D >> DADS fdf

[-<units>]

Specifies the units of the original H3D model. See Unit Options below.

Mass unit

GRAM, KILOGRAM, MEGAGRAM, POUND_MASS, SLUG, OUNCE_MASS, KPOUND_MASS

Length unit

INCH, FOOT, MILE, MILLIMETER, CENTIMETER, METER, KILOMETER

Force unit

OUNCE_FORCE, POUND_FORCE, KPOUND_FORCE, DYNE, NEWTON, KILOGRAM_FORCE, KNEWTON

Time unit

MILLISECOND, SECOND, MINUTE, HOUR

Translate xxx.pch with the optional units to yyy_flex.h3d. The default is KILOGRAM, MILLIMETER, NEWTON, and SECOND

flexprep xxx.pch yyy_flex.h3d -METER -KILOGRAM_FORCE

Translate xxx.mnf to yyy_flex.h3d (units included in mnf file).

flexprep xxx.mnf yyy_flex.h3d 

Translate xxx_flex.h3d to yyy.mtx with node 1, node 1001 and modes 7, 8, 9, 11, 12, 13, 14, 15 selected. Unit of the resulting mtx file can be specified (as METER in this example) in the options list. The default is KILOGRAM, MILLIMETER, NEWTON, and SECOND. In general, modes 1-6 are the rigid body modes so the valid mode number should start from 7.

flexprep xxx_flex.h3d yyy.mtx TTTTTTTTF +1+1001 +7:9+11:15 -METER

Includes all nodes and modes (rigid body modes will be automatically excluded). Use XZ plane (in basic coordinate frame) as the mirroring plane and translate to mtx file the mirrored part.

flexprep xxx_flex.h3d yyy.mtx TTTTTTTTF +INTERFACE_NODES +ALL -METER -MIRROR_XZ

Use XZ plane (in basic coordinate frame) as the mirroring plane and create the mirrored part of the original one.

flexprep xxx_flex.h3d yyy_flex.h3d -MIRROR_XZ

If interface nodes block exists in the H3D file (e.g. read from mnf file interface node block or if the H3D is from flexprep/OptiStruct analysis), then interface nodes will be selected, plus additional non-interface nodes (non-force bearing node, or sensory nodes). Suppose the interface nodes recorded in H3D file are 1 and 1001, the above command will select nodes 1, 1001, 6, 7, 8, and 10.

flexprep xxx_flex.h3d yyy.mtx TTTTTTTTF +I+6:8+10 +ALL -METER

Compute Craig-Bampton modes with nodes 1 and 1001 as the interface nodes and 10 eigen modes. Orthogonalize the mode set and write the results as well as the element stress modes into yyy_flex.h3d file.

flexprep xxx.blk yyy_flex.h3d  CB  +1+1001 10 -STRESS 

Compute Craig-Bampton modes with nodes 1 and 1001 as the interface nodes and eigen modes up to 1000 HZ. Orthogonalize the mode set and write the results into yyy_flex.h3d file.

flexprep xxx.blk yyy_flex.h3d  CB  +1+1001 1000.0 HZ

Same as above CB, but use existing OptiStruct result files from previous partial or full CB analysis.

flexprep xxx.blk yyy_flex.h3d  CBX  +1+1001 1000.0 HZ

Same as above CB, but only write out fem files (for manually invoking OptiStruct analysis). No H3D file will be produced. The -PURGE option removes the OptiStruct output files unused in CB procedure.

flexprep xxx.blk dummy.h3d  CB  +1+1001 1000.0 HZ -FEMONLY -PURGE

Same as above CB, but use the specified fem file(s) for OptiStruct analysis. File type can be -EIG, -FRE, -STA, or -SRA. One, or more options (up to 4) can be specified.

flexprep xxx.blk yyy_flex.h3d  CB  +1+1001 1000.0 HZ -EIG:zzz_eig.fem

Compute Free-Free eigen modes with frequency up to 1000 HZ. Write the results as well as the element stress modes into yyy_flex.h3d file.

flexprep xxx.blk yyy_flex.h3d  FF  +1+1001 1000.0 HZ -STRESS 

Compute 10 free-free eigen modes and frequency-response attachment modes with nodes 1 and 1001 as the interface nodes. Detect and remove possible dependent modes, orthogonalize the mode set and write the results into yyy_flex.h3d file.

flexprep xxx.blk yyy_flex.h3d  FR  +1+1001 10