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Python Scripting in ABAQUS

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					                        Python Scripting in ABAQUS

                                  Kevin Maxwell
                               Texas A&M University
                                 October 31, 2006

Introduction
ABAQUS CAE provides a graphical user interface that allows the user to create finite
element models that can then be analyzed in ABAQUS Standard. For every feature in
CAE, there is a corresponding Python script command that the program uses when
creating the model. If the language is understood well enough, an entire model can be
created simply by running a script file.

While one could write an entire script from scratch, ABAQUS provides several easier
methods that autogenerate Python commands. When a model is created in CAE, two
files are automatically created in the work directory. The replay file records every action
that is performed in CAE including camera zoom/panning commands and also any
mistakes that were made and then corrected. This file can be run to “replay” all the work
that has been done on the model. The recover file records only the minimum necessary
commands to recreate the model. If an error occurs and CAE closes without saving, the
recover file can be run to recreate the model. When a model is saved, CAE uses the
recover file to write a journal file. The journal file is a comprehensive script that shows
all work saved on the model. Note that the recover file is deleted whenever the model is
saved and all of its commands are transferred to the journal file. The recover and journal
files provide an easy alternative to writing Python scripts from scratch. One can simply
define a model in CAE and then save the Python commands from the recover or journal
files as a separate script file.

There are several valuable sources of information pertaining to scripting in ABAQUS.
The ABAQUS Scripting User’s Manual and ABAQUS Scripting Reference Manual are
invaluable resources that are included in the ABAQUS documentation. The user’s
manual gives an overview to scripting while the reference manual provides in-depth
coverage of every scripting command used in ABAQUS. Another source of information
can be found at http://www.python.org . This website contains numerous resources
dealing with the Python language in general.

Example
Templates for square and hexagonal composite fiber orientations were created using
Python scripts and ABAQUS. The respective scripts create a model in ABAQUS CAE
and assign a mesh to this model. The fiber volume fraction as well as the global element
size can be specified. Sample meshes for both templates are given in Figure 1 and Figure
2. Note that symmetry planes were exploited in order to model ¼ of the square or
hexagon.
                             Figure 1: Square Mesh




                            Figure 2: Hexagonal Mesh



The python scripts used to create these models are included below. Some of the
commands were autogenerated using ABAQUS CAE and the associated recover/journal
files. However, most of the commands were written from scratch in Notepad++, a free
text editor with multi-language support. The use of scripting made the definition of the
model geometry much easier to define as well as allowing the parameterization of the
fiber size and mesh.

The mesh was developed so that the elements are most uniform along the fiber matrix
interface. To accomplish this, a small square partition in the lower left of the model and
a circular partition with radius greater than the fiber radius were added to the mesh.
These partitions can be seen in Figure 1 and Figure 2. It should be noted that time
constraints did not allow the meshes for either template to be completely refined. For the
square model, the user can input global element size and the number of seeds along the
fiber matrix interface. For the hexagonal model, the user can input global element size,
interface seed number, and number of seeds along the top edge (this number has to be
specified in order to make this mesh edge symmetric). Options such as biasing the
element size along different directions can be added to the script at a later date.

				
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