Using the Interaction
Wizard
Nonlinear Structural Analysis
and Thermal Analysis include a powerful tool for
identifying and creating common types of interactions
between bodies in an assembled part or product. The
interaction wizard simplifies the process of creating
contact pairs and fastened pairs in a model. The wizard
searches a model for geometric faces that lie within a
specified separation distance, then creates either
contact pairs (see
Contact Pairs) or
fastened pairs (see
Creating Fastened Pairs) for
every pair of detected faces; general analysis
connections (see
Creating General Analysis
Connections) are also created automatically to act
as supports for the contact pairs and fastened pairs. You
can specify the areas of the model to search, the
separation distance within which faces are likely to
interact, the type of interaction that is created
(contact pair or fastened pair), and the parameters
assigned to each created interaction.
You can also use the
interaction wizard to quickly review and modify any
preexisting contact pairs and fastened pairs in a
model.
Using the interaction wizard is
a four-step process:
-
Define the search
criteria that are used to locate
interactions.
-
Specify default
attributes that are used to define all located
interactions.
-
Perform the search and
review the located interactions.
-
Edit the attributes for
individual interactions as necessary.
Each step in the process
uses a unique dialog box. When you have completed the
information in one dialog box, the next appropriate
dialog box appears; you can also use the Back button to
return to previous dialog boxes if necessary.
Interactions are not added to the model while you are
working in the interaction wizard. Once you are satisfied
with the interactions defined in the wizard, click
Finish to add them all
simultaneously to the specification tree.
Using the
Interaction Wizard: Creates contact pairs
and fastened pairs for all model faces within a specified
distance of each other.
The following topics cover the steps in using the
interaction wizard:
Defining Search
Parameters for the Interaction Wizard
When you click the Find Interactions icon , Nonlinear
Structural Analysis or Thermal Analysis opens the
Step
1 dialog box for the interaction wizard. In
the first step of the interaction wizard you indicate
whether you are searching for new interactions,
reviewing existing interactions, or both searching for
new interactions and reviewing existing
interactions.
Before using the interaction wizard, you should set
the current step in the active Analysis Case (see
Analysis Cases). Newly
detected contact pairs will be created in the current
step and propagated to all subsequent steps. Newly
detected fastened pairs will be created in the initial
step (regardless of the current step) and are active
through all steps in the analysis case. When reviewing
existing interactions, the interaction wizard displays
only those interactions that are active in the current
step.
If you are searching for new interactions, you must
provide some search criteria. These criteria include
the search domain, the maximum distance between
potentially interacting faces, and an option for
extending surfaces in the created interactions.
When searching for new interactions, the interaction
wizard considers only faces on different bodies in a
model. You cannot use the interaction wizard to define
self-contact or interactions between different faces on
the same body. The interaction wizard uses the
following specifications to define a body:
-
Multiple solid features (for example, two pad
features) within the same part are not considered
separate bodies, even if they are unconnected (see
Figure 61).
-
Multiple surface or volume features (such as in
a geometrical set) within the same part are
considered separate bodies (see Figure 61).
-
Multiple part instances within an assembled
product are considered separate bodies.
-
One-dimensional beam and wire geometries are not
considered bodies.
The interaction wizard searches for interactions
between all bodies listed in the specification tree. If
a body is generated from an existing body (for example,
a volume feature is extruded from an existing surface
feature or two existing volume features are joined to
form a third volume feature), interactions may be
detected involving both the original body and the
generated body. To avoid creating excessive or
duplicate interactions, the Include meshed geometry
only option allows you to search only those
bodies with a mesh assignment (this option is turned on
by default); enabling this option typically eliminates
from the search domain those bodies used as
construction or reference geometry. The interaction
wizard cannot detect interactions involving mesh
objects without any underlying geometry.
In addition, the interaction wizard uses some
unmodifiable criteria during the search. In particular,
two faces must be oriented toward each other. The
interaction wizard compares the surface normals at the
points of closest approach between two faces; if the
two faces are offset by more than 45°, the
interaction wizard will not create an interaction for
these faces (see Figure 62).
If two faces intersect each other, they must be
oriented toward each other to be considered by the
interaction wizard (see Figure 63).
In Figure 63 one of the faces (Surface
B) is completely
enclosed within the other body. The interaction wizard
considers separation distances on both sides of each
face (interior and exterior) when searching for
potential interactions. Therefore, this enclosed face
is detected only if its depth of penetration is less
than the specified separation distance criterion for
the search. You can use the clash tool in the Assembly
Design workbench to identify intersecting or enclosed
faces that are not detected by the interaction wizard
(see
Detecting Clashes in the CATIA V5
Assembly Design User's Guide).
The interaction wizard also determines whether or
not two faces are aligned with each other. For an
interaction to be created between two faces, a surface
normal from some point on one face must pass through
the opposing face. For example, none of the faces in
Figure 64 are considered aligned by
the interaction wizard.
The surface extension option can be used to ensure
that the surfaces in an interaction cover an
appropriate area of the model. This option is
controlled by an “extension angle.” All
faces adjacent to each face in a detected interaction
are also identified in the model. The minimum angle
between the surface normals of the detected face and
the adjacent face is measured along their common edge;
if the angle is less than the specified extension
angle, the adjacent face is included in the
interaction. The surface extensions also propagate to
faces adjacent to the updated surface. Figure 65 illustrates a situation in
which surface extensions can be used to capture all of
the faces on a contoured surface.
This task shows you how to complete
Step
1 of the interaction wizard.
-
If necessary, set the current step in the
specification tree to the step in which new
interactions should be created.
-
Click the Find Interactions icon .
The Find Interactions Wizard: Step
1 dialog box appears.
-
Specify whether you want to review existing
interactions or search for new ones:
-
Choose Detect new interactions
to search for potential interactions in the
model.
-
Choose Manage existing
interactions to use the
interaction wizard to review and modify
previously created contact pairs and fastened
pairs that are active in the current step.
Parameters for contact pairs can be modified
only if the current step is the step in which
the contact pair was created (with the
exception of the connection behavior, which
can be modified in any step). If you select
this option, click Next to move directly
to Step 3 of the
interaction wizard (see
Reviewing and
Creating Interactions Using the Interaction
Wizard); you can ignore the remainder of
this procedure.
-
Choose Both to search for new
interactions and review previously created
interactions. After searching the model, the
interaction wizard lists both newly detected
and previously created interactions
simultaneously.
-
Specify the search domain:
-
Choose Whole model to compare
faces on every part in the model.
-
To search for interactions between
specific parts in an assembled product,
choose Select components and
select the specific parts whose faces you
want to compare. If you select a product from
the specification tree, all part instances in
that product are added to the search
domain.
The Select components field
is updated to reflect your selection.
-
By default, the interaction wizard searches
only those geometric bodies that have a mesh
assignment. This criterion prevents the creation
of interactions involving construction or
reference geometry. You should therefore assign a
mesh to all bodies that are significant to your
analysis before using the interaction wizard.
To search for interactions between all bodies
in the specified search domain, regardless of
their mesh assignments, toggle off Include meshed
geometry only.
-
In the Detect interactions within
tolerance field, enter the maximum
distance between faces that are likely to
interact. The interaction wizard can create
interactions for any faces that are within this
separation tolerance, provided they are aligned
and oriented toward one another.
-
Toggle on Extend each surface by
angle, and enter an appropriate
extension angle to extend the interaction
surfaces to include faces adjacent to those
detected by the search.
-
Click Next to proceed to the
next dialog box in the interaction wizard.

Defining Default
Interaction Parameters for the Interaction
Wizard
When you have finished defining the search
parameters (see
Defining Search Parameters for the
Interaction Wizard),
Nonlinear Structural Analysis or Thermal Analysis opens
the Step
2 dialog box for the interaction wizard. In
the second step of the interaction wizard you specify
the default parameters that are used to create
interactions between faces detected by the search. If
you opted to only manage existing interactions in Step
1, the Step
2 dialog box is skipped, and the interaction
wizard proceeds directly to Step 3 (see
Reviewing and Creating Interactions
Using the Interaction Wizard).
The default parameters include the type of
interaction (contact pair or fastened pair), the
interaction behavior, the sliding formulation, and
surface adjustment settings. The specified default
parameters are assigned to all newly detected
interactions. However, you will have the opportunity to
modify the parameters on individual interactions before
adding them to the model.
This task shows you how to create contact
pairs for all detected interactions. To create
fastened pairs, see the task immediately
following this one. For more information about
contact pairs, see
Contact Pairs.
-
Select Contact as the Interaction
Type.
-
Select a Mechanical or Thermal Connection
Behavior from the specification tree.
The Interaction behavior field
is updated to reflect your selection.
-
Specify the Sliding formulation:
-
Choose Finite sliding to allow
for arbitrary separation, sliding, and
rotation of the two surfaces.
-
Choose Small sliding if there
will be relatively little sliding of one
surface along the other. The small-sliding
formulation is less expensive computationally
than the finite-sliding formulation.
-
To automatically reposition slave nodes
precisely onto the master surface during an
analysis, toggle on Adjust slave
nodes, and specify an adjustment
option:
-
Choose Adjust overclosed nodes
only to reposition only those
slave nodes that are initially penetrating
the master surface.
-
Choose Adjust nodes within,
and enter a distance to reposition all slave
nodes that initially lie within the specified
distance from the master surface.
-
Click Run to perform the
interaction detection and to proceed to the next
dialog box in the interaction wizard.
-
Before the next dialog box appears, a status
bar indicates the progress of the interaction
detection. If the progress is excessively slow,
click Stop to abort the search
and return to the Step 2 dialog box. You
should modify the search parameters (see
Defining Search Parameters for the
Interaction Wizard)
before performing the search again.
This task shows you how to create fastened
pairs for all detected interactions. To create
contact pairs, see the task above. For more
information about fastened pairs, see
Creating
Fastened Pairs.
-
Select Fastened as the
Interaction Type.
-
To automatically reposition slave nodes
precisely onto the master surface during an
analysis, toggle on Adjust slave
nodes.
-
Click Run to perform the
interaction detection and to proceed to the next
dialog box in the interaction wizard.
-
Before the next dialog box appears, a status
bar indicates the progress of the interaction
detection. If the progress is excessively slow,
click Stop to abort the search
and return to the Step 2 dialog box. You
should modify the search parameters (see
Defining Search Parameters for the
Interaction Wizard)
before performing the search again.
Reviewing and
Creating Interactions Using the Interaction
Wizard
Once the search for interactions is complete,
Nonlinear Structural Analysis or Thermal Analysis opens
the Step
3 dialog box for the interaction wizard.
This dialog box includes the Interactions
table, which summarizes all of the interactions and the
parameters assigned to them. The interactions that are
listed depend on the settings you specified in the
first step of the interaction wizard (see
Defining Search Parameters for the
Interaction Wizard): the
Interactions table can list newly
detected interaction candidates, existing interactions
that are active in the current step, or both newly
detected and existing interactions. Existing
interactions appear in the Interactions
table with an asterisk (*) in front of their name (see
Figure 66).
When you click on a row in the Interactions
table, the surfaces involved in the selected
interaction are highlighted in the model. Master
surfaces are highlighted in red; slave surfaces are
highlighted in green. You can toggle off Highlight in
viewport to disable surface highlighting.
This option may be helpful if you are selecting a large
number of interactions, since highlighting numerous
surfaces may negatively impact display performance.
The items in the Interactions table represent the
contact pairs and fastened pairs that will be added to
the specification tree when you click Finish.
Before adding these definitions, you can modify the
parameters for individual interactions, delete
interactions, or merge adjoining surfaces into a single
interaction definition (merging is available only for
newly detected interactions).
This task shows you how to complete
Step
3 of the interaction wizard.
-
If desired, disable the highlighting of slave
and master surfaces on the model by toggling off
Highlight in viewport.
-
You can control the visibility of model bodies
using the Visibility Options:
-
Select Whole Model to display
the entire model with the selected master and
slave surfaces highlighted.
-
Select Master and Slave only
to display only the parts that are connected
to the selected master and slave surface;
both the master and the slave surfaces are
highlighted.
-
Select Master only to display
only the part that is connected to the
selected master surface; only the master
surface is highlighted.
-
Select Slave only to display
only the part that is connected to the
selected slave surface; only the slave
surface is highlighted.
-
To change the identifier for an interaction,
click in the Name field and type a new
name. This name will be used for the general
analysis connection and contact pair or fastened
pair when they are added to the specification
tree.
-
To delete an interaction from the Interactions table,
highlight the interaction row and click
Delete. If you delete an
existing interaction, the interaction wizard
prompts you to specify whether or not the general
analysis connection associated with the deleted
contact pair or fastened pair should also be
deleted. An existing contact pair can be deleted
only if the current step is the step in which the
contact pair was created.
-
To change an interaction's parameters,
highlight the interaction row and click
Edit. Nonlinear Structural
Analysis or Thermal Analysis opens the
Edit
Interaction dialog box, which is
discussed in
Editing Detected or Existing
Interactions Using the Interaction
Wizard.
-
If two or more interactions involve surfaces
that are joined at a common edge, you can merge
them into a single interaction using the
procedure below. To be merged, interactions must
have identical parameters, and the adjoining
surfaces must have common assignments (either
both are master surfaces or both are slave
surfaces). You cannot merge existing
interactions.
-
Using [Ctrl]+Click or [Shift]+Click, select the
interactions in the Interactions table
that you want to merge.
-
If desired, you can merge only those
interactions whose surfaces meet at an
angle within a specified range. This angle
is measured as the minimum offset between
the two surface normals along the common
edge. Toggle on Merge
interactions within angle, and
enter the desired angle.
-
Click Merge.
The highlighted interactions are
replaced with a single entry in the
Interactions
table.
-
When you are satisfied with the contents of
the Interactions table, click
Finish.
Nonlinear Structural Analysis or Thermal
Analysis creates a contact pair or a fastened
pair for each entry in the table and adds it to
the specification tree. If the Interactions table displays
existing interactions, these interactions are
updated with any changes you made in the
interaction wizard.
Editing Detected or
Existing Interactions Using the Interaction
Wizard
In the interaction wizard Step 3 dialog
box (see
Reviewing and Creating Interactions
Using the Interaction Wizard), if
you highlight an interaction (or multiple interactions)
and click Edit, Nonlinear Structural
Analysis or Thermal Analysis opens the Edit
Interaction dialog box. The Edit
Interaction dialog box allows you to modify
the parameters for the highlighted interactions.
The Edit
Interaction dialog box is similar to the
Step
2 dialog box for the interaction wizard (see
Defining Default Interaction Parameters
for the Interaction Wizard);
however, the parameters specified in the Edit
Interaction dialog box apply to only the
interactions that were highlighted in the Step 3 dialog
box. You can change whether the interactions are
contact pairs or fastened pairs and adjust the
behavior, sliding formulation, and adjustment options
associated with the interactions. If you are editing
only a single interaction, you can also modify the
interaction's name.
Most contact pair parameters can be modified only if
the current step is the step in which the contact pair
was created. The connection behavior for a contact pair
can be modified in any step. Modifications to fastened
pair parameters are always applied to the initial step,
regardless of the current step.
The following task shows you how to modify the
parameters for an interaction using the
Edit
Interaction dialog box.
-
If you are editing a single interaction, you
can change the interaction identifier by editing
the Name field. This name will
be used for the general analysis connection and
contact pair or fastened pair when they are added
to the specification tree.
-
The options for modifying the interaction
parameters are identical to those used in the
Step
2 dialog box for the interaction
wizard. Refer to the procedures in
Defining Default Interaction
Parameters for the Interaction Wizard
for instructions on using these options.
-
To reverse the master and slave surface
assignments in the interactions, toggle
Swap
master and slave surfaces.
-
Click OK.
Nonlinear Structural Analysis or Thermal
Analysis returns to the Step 3
dialog box for the interaction wizard and applies
your changes to the Interactions table (see
Reviewing and Creating
Interactions Using the Interaction
Wizard).
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