flexprep

Creates and translates flexbody H3D files.

Syntax

flexprep <source>.<bdf|nas|dat|fem|blk> <target>.h3d <mode_type_option> <+interface_node_list> [upper_freq [HZ]] [-<units>] [-<stress>] -ospath:<DEFAULT|directory>

flexprep <source>.pch <target>.h3d [-<units>]

flexprep <source>.mnf <target>.h3d [invar_option] [-<NO_UNIT_CONV>]

flexprep <source>.h3d <target>.h3d [-<mirror option>]

flexprep <source>.h3d <target>.mtx [invar_option] [+node_list] [+mode_list] [-<units>] [-<mirror option>]

flexprep <source>.h3d <target>.mnf flexprep <source>.h3d <target>.fdf [+mode_list] [-<units>]

flexprep <source>.h3d <target>.<fes|asc>

Application

Translators

Description

Creates flexbody H3D files using OptiStruct.

Creates flexbody H3D file from ADAMS MNF and Nastran PCH.

Translates flexbody H3D file to ADAMS MTX, Altair H3D (mirrored), ADAMS MNF, DADS FDF, and nCode FES.

Inputs

Nastran Bulk Data File to 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.
[-<strain>]
If specified, strain 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 to H3D
[-<units>]
Specifies the units of the original Nastran punch file. See Unit Options below.
ADAMS MNF to 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 to H3D
[-<mirror_option>]
Specifies the plane about which to mirror the H3D model. Available options are:
  • MIRROR_XY
  • MIRROR_XZ
  • MIRROR_YZ
H3D to 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 the units of the original H3D model. 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 to DADS fdf
[-<units>]
Specifies the units of the original H3D model. See Unit Options below.

Unit Options

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

Example

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

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.

Include 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 +ALL +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

Comments

flexprep checks the file extensions on the specified source and target files to determine the appropriate translation.