Model data define the model used in the
analysis; for example, the parts, materials, initial and boundary conditions,
and physical constants. More information about model data can be found in
The Abaqus object model
and
Assembly Definition.
Abaqus
does not write all the model data to the output database; for example, you
cannot access loads, and only certain interactions are available. Model data
that are stored in the output database include parts, the root assembly, part
instances, regions, materials, sections, section assignments, and section
categories, each of which is stored as an Abaqus Scripting Interface
object. These components of model data are described below.
Parts
A part in the output database is a finite element idealization of an object.
Parts are the building blocks of an assembly and can be either rigid or
deformable. Parts are reusable; they can be instanced multiple times in the
assembly. Parts are not analyzed directly; a part is like a blueprint for its
instances. A part is stored in an output database as a collection of nodes,
elements, surfaces, and sets.
The root
assembly
The root assembly is a collection of positioned part instances. An analysis
is conducted by defining boundary conditions, constraints, interactions, and a
loading history for the root assembly. The output database object model
contains only one root assembly.
Part
instances
A part instance is a usage of a part within the assembly. All
characteristics (such as mesh and section definitions) defined for a part
become characteristics for each instance of that part—they are inherited by the
part instances. Each part instance is positioned independently within the root
assembly.
Materials
Materials contain material models comprised of one or more material property
definitions. The same material models may be used repeatedly within a model;
each component that uses the same material model shares identical material
properties. Many materials may exist within a model database, but only the
materials that are used in the assembly are copied to the output database.
Sections
Sections add the properties that are necessary to define completely the
geometric and material properties of an element. Various element types require
different section types to complete their definitions. For example, shell
elements in a composite part require a section that provides a thickness,
multiple material models, and an orientation for each material model; all these
pieces combine to complete the composite shell element definition. Like
materials, only those sections that are used in the assembly are copied to the
output database.
Section
assignments
Section assignments link section definitions to the regions of part
instances. Section assignments in the output database maintain this
association. Sections are assigned to each part in a model, and the section
assignments are propagated to each instance of that part.
Section
categories
You use section categories to group the regions of the model that use the
same section definitions; for example, the regions that use a shell section
with five section points. Within a section category, you use the section points
to identify the location of results; for example, you can associate section
point 1 with the top surface of a shell and section point 5 with the bottom
surface.
Analytical rigid
surface
Analytical rigid surfaces are geometric surfaces with profiles that can be
described with straight and curved line segments. Using analytical rigid
surfaces offers important advantages in contact modeling.
Rigid
bodies
You use rigid bodies to define a collection of nodes, elements, and/or
surfaces whose motion is governed by the motion of a single node, called the
rigid body reference node.
Pretension
Sections
Pretension sections are used to associate a pre-tension node with a
pre-tension section. The pre-tension section can be defined using a surface for
continuum elements or using an element for truss or beam elements.
Interactions
Interactions are used to define contact between surfaces in an analysis.
Only contact interactions defined using contact pairs are written to the output
database.
Interaction
properties
Interaction properties define the physical behavior of surfaces involved in
an interaction. Only tangential friction behavior is written to the output
database.
The objects stored as model data in an output database are
similar to the objects stored in an
Abaqus/CAE
model database. However, the output database does not require a model name
because an analysis job always refers to a single model and the resulting
output database can contain only one model. For example, the following
Abaqus Scripting Interface
statements refer to an Instance object in the model
database:
You can use the prettyPrint method to display a text
representation of an output database and to view the structure of the model
data in the object model. For example, the following shows the output from
prettyPrint applied to the output
database created by the
Abaqus/CAE
cantilever beam tutorial: