A single finite element file or several finite element files are referenced
in the item FILE
in the command FEM_INPUT
.
However, all finite element files should have the same number of elements,
nodes, material properties, element groups, nodes groups etc. The only
difference allowed between the different input finite element files
is that the analysis types can vary. The analysis type can either be
linear static, nonlinear static, modal eigenfrequency or frequency response
analysis.
The FEM_INPUT
command is applied for reading the finite element files in the following
way:
FEM_INPUT
ID_NAME = id_read_files
FILE = fe_file_name_1
FILE = fe_file_name_2
FILE = fe_file_name_3
...
END_
The possibilities available to the user for loading the analysis model
when creating the optimization model depend on the chosen solver (see Post-Processing of Optimization Results
and Solver Specific Features)
and the option set
(OPTIONS).
The model data is loaded using an internal interface.
After reading the model, the following FE objects are available for further
reference in the optimization task:
- node groups
- element groups
- nodes
- elements
- coordinate systems
- materials
- properties
- element types
- boundary conditions (depending on the
OPTIONS
)
- load cases
Analysis results used as terms for objective or constraint, so called
design responses
(DRESP
),
are built by referring the load case
numbers for the desired responses.
The load cases
in the first file (fe_file_name_1
)
are numbered using the original load case
numbers used in the finite element file.
The load cases
in the second file (fe_file_name_2
)
are numbered using the original load case
numbers used in the finite element file plus 10.000.
The load cases
in the third file (fe_file_name_3
)
are numbered using the original load case
numbers used in the finite element file plus 20.000
and etc.
For example, the load cases
1, 3 and 4 in the first finite element file have the numbers 1, 3 and
4 in the parameter file, the load cases
1, 3 and 4 in the second finite element file have the numbers 10001,
10003 and 10004 in the parameter file, the load cases
1, 3 and 4 in the third finite element file have the numbers 20001, 20003
and 20004 in the parameter file and etc.
In
Solver Specific Features
the different allowed analysis types for the specific solvers
are described. In addition,
About Load Case Specification (LC_SET)
describes how the load case
numbers for the different finite element solvers are applied in the design
response definitions (DRESP
).
This is especially important for the finite element input files using
no numbers when defining load cases.
For the finite element solvers using no numbers the general rule is that
the load cases
have the numbers according to the order within they are defined. Meaning
that the load case
number one will always have the load number of one for Tosca Structure
etc.
Remarks
- A model link can only be made once for an optimization task, that is, the
command
FEM_INPUT
can only be used once in a parameter
file.
- Several analysis files can be added, that is, the item
FILE
can be repeated several times. The first file in the list of files will
be handled as main file, which means that the configuration of the
finite element model will be read from this file. The second and all
later referenced files will be used to perform a finite element calculation.
The model in these files must be identical to the original FE model.
The files will be modified during the optimization.