ansys.mapdl.core.Mapdl.cdwrite

Mapdl.cdwrite(option='', fname='', ext='', fnamei='', exti='', fmat='', **kwargs)

Writes geometry and load database items to a file.

Mechanical APDL Command: CDWRITE

Parameters:

option

Selects which data to write:

ALL

Write all appropriate geometry, material property,

load, and component data (default). Two files will

be produced. ``Fname.Ext`` will contain all data items

mentioned in “Notes”, except the solid model

data. ``Fnamei.Exti`` will contain the solid model

geometry and solid model loads data in the form of

``IGES`` commands. This option is not valid when

``CDOPT,ANF`` is active.

COMB

Write all data mentioned, but to a single file,

``Fname.Ext``. Solid model geometry data will be

written in either ``IGES`` or ``ANF`` format as specified

in the ``CDOPT`` command, followed by the remainder of

the data in the form of ANSYS commands. More

information on these (IGES/ANF) file formats is

provided in “Notes”.

DB

Write all database information except the solid model

and solid model loads to ``Fname.Ext`` in the form of

ANSYS commands. This option is not valid when

``CDOPT,ANF`` is active.

SOLID

Write only the solid model geometry and solid

model load data. This output will be in IGES or

ANF format, as specified in the ``CDOPT``

command. More information on these (``IGES/ANF``) file

formats is provided in “Notes”.

GEOM

Write only element and nodal geometry data. Neither

solid model geometry nor element attribute data

will be written. One file, ``Fname.Ext``, will be

produced. Use ``CDREAD,DB`` to read in a file written

with this option. Element types [``ET``] compatible

with the connectivity of the elements on the file

must first be defined before reading the file in

with ``CDREAD,DB``.

CM

Write only node and element component and geometry

data to ``Fname.Ext``.

MAT

Write only material property data (both linear and

nonlinear) to ``Fname.Ext``.

LOAD

Write only loads for current load step to

``Fname.Ext``.

SECT

Write only section data to ``Fname.Ext``. Pretension

sections are not included.

fname

File name and directory path (248 characters maximum,

including the characters needed for the directory path).

An unspecified directory path defaults to the working

directory; in this case, you can use all 248 characters

for the file name.

ext

Filename extension (eight-character maximum).

fnamei

Name of the IGES file and its directory path (248

characters maximum, including directory). If you do not

specify a directory path, it will default to your working

directory and you can use all 248 characters for the file

name.

exti

Filename extension (eight-character maximum).

fmat

Format of the output file (defaults to BLOCKED).

BLOCKED

Blocked format. This format allows faster

reading of the output file. The time savings is

most significant when BLOCKED is used to read

.cdb files associated with very large models.

UNBLOCKED

Unblocked format.

Returns:

str

Mapdl command output.

Notes

Load data includes the current load step only. Loads applied to the solid model (if any) are automatically transferred to the finite element model when this command is issued. cdwrite writes out solid model loads for meshed models only. If the model is not meshed, the solid model loads cannot be saved. Component data include component definitions, but not assembly definitions. Appropriate numoff commands are included at the beginning of the file; this is to avoid overlap of an existing database when the file is read in.

Solution control commands are typically not written to the file unless you specifically change a default solution setting.

cdwrite does not support the gsbdata and gsgdata commands, and these commands are not written to the file.

The data may be reread (on a different machine, for example) with the cdread command. Caution: When the file is read in, the numoff,MAT command may cause a mismatch between material definitions and material numbers referenced by certain loads and element real constants. See numoff for details. Also, be aware that the files created by the cdwrite command explicitly set the active coordinate system to Cartesian ( csys,0).

You should generally use the blocked format ( Fmat = BLOCKED) when writing out model data with cdwrite. This is a compressed data format that greatly reduces the time required to read large models through the cdread command. The blocked and unblocked formats are described in The CDWRITE (CDB) File Format

If you use cdwrite in any of the derived products (Ansys Mechanical Pro, Ansys Mechanical Premium), then before reading the file, you must edit the Jobname.cdb file to remove commands that are not available in the respective component product.

The cdwrite command does not support (for beam meshing) any line operation that relies on solid model associativity. For example, meshing the areas adjacent to the meshed line, plotting the line that contains the orientation nodes, or clearing the mesh from the line that contains orientation nodes may not work as expected. For more information about beam meshing, see Meshing Your Solid Model in the Modeling and Meshing Guide.

If you issue cdwrite to write a .cdb file containing a user-defined element, manually insert usrelem and usrdof commands in the .cdb file to provide the user- defined element characteristics. Insert the two commands after the et command (defining the user-defined element) and before the EBLOCK command. (If multiple element types are defined in the .cdb file, insert the The type statement command to select the user-defined element. Place it before usrelem and usrdof.)

If radiosity surface elements ( SURF251 or SURF252 ) are present in the model, a radiosity mapping data file, Fname.RSM, is also saved when the cdwrite command is issued. For more information, see Advanced Radiosity Options

*IGES and ANF File Formats for Solid Model Geometry Information*

The format used for solid model geometry information is determined by the current cdopt command setting. The default format is IGES.

IGES option (default) to write solid model information ( cdopt, IGS):

• Before writing solid model entities, select all corresponding lower level entities ( allsel,BELOW,ALL).

• Section properties assigned to areas, lines and other solid model entities are not maintained when the model is exported.

• If you issue cdwrite after generating a beam mesh with orientation nodes, the database file will contain all of the nodes for every beam element, including the orientation nodes; however, the orientation keypoints that were specified for the line ( latt ) are no longer associated with the line and won’t be written out to the geometry file. All associativity between the line and the orientation keypoints is lost.

• For beam meshing, this option does not support any line operation that relies on solid model associativity. For example, meshing the areas adjacent to the meshed line, plotting the line that contains the orientation nodes, or clearing the mesh from the line that contains orientation nodes may not work as expected.

• Concatenated lines are not written. The line segments that make up the concatenated lines are written; however, if the command encounters an area that contains a concatenated line, the write operation halts (that area cannot be recreated during the read operation). If your model has areas that contain concatenated lines, you must first list these and then unconcatenate them before issuing the cdwrite command. Similarly, hardpoint information cannot be written.

ANF option to write solid model information ( cdopt, ANF):

• Writes all model information in the database (regardless of select status) to the archive file; however, when you restore the database using this archived file, the select status of entities is also restored.

• Restores all line attributes, including orientation keypoints. It also writes out any components (not assemblies) that consist of solid model entities.

• Halts cdwrite when a concatenated line or an area that contains a concatenated line is detected. You must delete the concatenated lines before issuing cdwrite. Similarly, hardpoint information cannot be written.

This command is also valid in SOLUTION.

Examples

Create a basic block and save it to disk.

>>> mapdl.prep7()
>>> mapdl.block(0, 1, 0, 1, 0, 1)
>>> mapdl.et(1, 186)
>>> mapdl.esize(0.25)
>>> mapdl.vmesh('ALL')
>>> mapdl.cdwrite('DB', '/tmp/mesh.cdb')
TITLE =
NUMBER OF ELEMENT TYPES =      1
64 ELEMENTS CURRENTLY SELECTED.  MAX ELEMENT NUMBER =   64
425 NODES CURRENTLY SELECTED.     MAX NODE NUMBER =     425
8 KEYPOINTS CURRENTLY SELECTED. MAX KEYPOINT NUMBER =   8
12 LINES CURRENTLY SELECTED.     MAX LINE NUMBER =      12
6 AREAS CURRENTLY SELECTED.     MAX AREA NUMBER =       6
1 VOLUMES CURRENTLY SELECTED.   MAX VOL. NUMBER =       1
WRITE ANSYS DATABASE AS AN ANSYS INPUT FILE: /tmp/mesh.cdb

Optionally load the mesh into Python using the archive reader.

>>> from ansys.mapdl import reader as pymapdl_reader
>>> mesh = pymapdl_reader.Archive('/tmp/mesh.cdb')
>>> mesh
ANSYS Archive File mesh.cdb
Number of Nodes:              425
Number of Elements:           64
Number of Element Types:      1
Number of Node Components:    0
Number of Element Components: 0