
This
task will show you how to compute object sets.
In this particular example, you will see how to compute a
mesh.
Computing a mesh will enable the analysis of any object of Restraints,
Loads and Masses type, without requiring the computation of a solution.
A finite element computation is a succession of data
manipulation processes in which input data resulting from a previous
process (or directly input by the user) is converted into output data ready
to be used by a subsequent process. Such readytouse data is stored in
program objects sets such as those appearing in the analysis features tree
under Analysis Cases (Restraints, Loads, Masses, Solutions) objects sets.
When data contained in such an objects set is ready for use
in the subsequent finite element computation process, the object has been
computed and can be analyzed. Thus, computing an objects set consists in
generating finite elements results for all objects and objects sets
necessary to analyze the specified objects set.
The computation of an objects set requires two distinct
actions:

First, the userdefined specifications attached to each
object belonging to the objects set in the specification tree must be
translated by the preprocessor into solverinterpretable commands.
Since solvers can only interpret data applied on mesh entities (nodes and
elements), this first translation step requires the existence of a mesh
support for converting user input specifications on the geometry into
explicit solver commands on nodes and elements.

Next, the solver translates the solver commands into data
ready for algorithmic treatment as required by the numeric procedure
invoked.
Since algorithms deal only with operators dimensioned by the problem size
(number of degrees of freedom (degree of freedom)), this second
translation step requires the exact knowledge of the behavioral
hypotheses of the finite elements (properties), which contain the
required degree of freedom information.
As a result of such action, the program translates the
userdefined specifications into solverinterpretable commands applied on
mesh entities, and you can visualize on the mesh the result of this
translation. This analysis capability, used especially for displaying
program feedback on applied Restraints, Loads or Masses objects in the case
of large size models (when you do not wish the entire computation to be
performed), is available with a contextual menu:

Restraint, Load and Mass type objects, in the form of the
object Visualization on Mesh action

Restraints, Loads, Masses and Solutions objects sets, in
the form of the following objects set actions:
A prerequisite to these actions is the existence of a mesh
part. 

Avoid having CATAnalysis documents automatically saved.
Otherwise, on some models, each computation will be followed by a Save
operation, thus making temporary data become persistent data.
To do this:

Select Tools > Options > General.

Select No automatic backup.
A warning message appears to inform you that you have
to restart your CATIA session after selecting this option. 

Click OK in the Options dialog box.



Edit the mesh part specifications.
To do this:

Doubleclick OCTREE Tetrahedron Mesh.1
in the specification tree.

Enter 11mm as Mesh size
value.

Click OK.
Note that the following sets are now non uptodate:
Nodes and Elements, Properties, Restraints,
Loads.


Click Compute
.
The Compute dialog box
appears.

All: all objects defined in the analysis
features tree will be computed.

Mesh Only: only the mesh, property,
material, restraints, loads, masses specifications will be updated
without requiring the computation of a solution.

Analysis Case Solution Selection: only a
selection of userspecified analysis solutions will be computed,
with an optimal parallel computation strategy.

Selection by Restraint: all the cases
that share the same Restraints set will be computed.

Do not use this option if you want to compute cases that
reference a multiload set. 

This option is only available with the
ELFINI Structural Analysis (EST) product. 


Select Mesh Only from the list.

Click OK.
Both the Computation Status dialog box and the
Computing... progress bar appear.
The progress bar provides a series of status messages
(Meshing, Factorization, Solution)
that inform you of the degree of advancement of the computation
process.
At any time, you can decide to interrupt the
computation process in order to modify parameters if you are not
satisfied of the current calculation or if you have forgotten
something.
All the entities that have been already updated hold their update
status.
To do this, click Cancel in the
Computing... progress bar.
The status of the Nodes and Elements set,
Properties set, Restraints set, Loads
set is changed to valid in the specification tree.

