Overview of the spot connector realization process and methods.
Spot Realization Process
Overview of the spot realization process.
Select the realization type.
mesh independent
Use for realizations that do not need a node connection, and the
connection is primarily defined via a solver-specific card, such
as CWELDs for Nastran.
mesh dependent
Use for all other cases.
If mesh dependent is selected, you must decided whether or not to adjust the
mesh or the realization.
Adjust mesh
Projection is done in a perpendicular way, and the mesh has to
be adapted to the projection points.
Adjust realizations
The mesh will not be modified, at the expense of non-normal or
incomplete realizations. Many realization types are defined with
head elements attached to body elements. In the case of these
realization types, the head elements realize the connection
without modifying the mesh. Then the body element is still
created in a normal direction.
Select a method for performing adjustments.
Adjust mesh
Sub-options include: quad transition and remesh.
Adjust realizations
Sub-options include: find nearest nodes, project and find nodes,
and ensure projection.
Choose whether or not the imprint should be skipped for quad
transition.
In stage 1, select the type of realization: Figure 1. Spot Realization Process
Spot Realization Methods
Overview of the different options for spot realization methods.
Mesh Independent
The mesh independent option is normally used for solver-specific realization types. A
post-script is performed during realization to define the solver specific connection. For
example, for the Nastran CWELD of ELEMID option, the shells
which are in contact are observed and defined in the CWELD card. Figure 2. Mesh Independent
The quad transition option creates perfectly shaped quad elements around the
projection points. By default, the quad size is determined by the average mesh size.
Alternatively, you can specify a specific quad size in the quad size field. Figure 4. Connectors Realized with Quad Transition using Different Quad Pattern
Sizes. The top, left image illustrates the initial model situation. The remaining
images illustrate connectors that have been realized with quad transition using
different quad pattern sizes: average, coarse, small. The regular quad pattern
size is highlighted and the red lines illustrate which nodes have been snapped to
a relevant feature or free edge.
For spot quad transition, automatic snapping and feature detection is enabled by
default via the allow snapping checkbox. This prevents the
creation of elements that are too small, and ensures that the geometry is not modified
too much.
Free edges and features with an angle greater than 25° are always taken into
account. If smaller feature angles should be considered, decrease the value in the
feature angle field (Preferences > Meshing Options). Feature angles smaller than 5° will not be considered.
By default, snapping is allowed by a distance of one third of the quad pattern
element size. In the case of a predefined quad pattern element size of 10.0, the outer
nodes can snap to features in a distance of 3.3. The algorithm also tries to snap all
three nodes of a quad pattern or none.
Figure 5. Connector Realized with Quad Transition using Adequate Quad Pattern
A spot connector line is created when quad transition is used and a line or a node
list is selected as the connector position, unless the split to
points checkbox is activated.
In Figure 6, spot connectors are at the same exact position, though
there is a notable difference. In both images, the connectors have been created along
a line, but in the left image the split to points checkbox was
enabled. In the left image, the quad transition pattern is aligned to the mesh; in the
right image the quad transition pattern is oriented along the spot connector line. All
elements around the spot connector line belong to the regular pattern. The number of
element pairs created along the spot connector line between the spot positions depends
on the average or selected mesh size, which can be from one to many. The quad elements
are distributed equidistant along the line.
In curved regions the inner and outer lengths of the element edges differ. Figure 6. Split to Points Example
Imprint
When creating mesh-dependent realizations with quad transitions, the quad transition
meshes can overlap and disturb each other if more than one set of connectors is
created too close to each other. Select the imprint option to
reconcile such transitions with each other and modify the underlying mesh to match the
results, creating a final result that is seamless and properly meshed.
To allow smaller imprint conflicts to be automatically resolved when connectors are
realized, the resolve conflicting imprints checkbox is enabled
by default. Overlapping elements are released, and a normal remesh of that area is
performed as long as the overlapping area is smaller than half the regular quad
transition element size. Larger conflicts may require a manual imprint.
The quad transition option creates perfectly shaped quad elements around the
projection points. By default, the quad size is determined by the average mesh size.
Alternatively, you can specify a specific quad size in the quad size field. Figure 7. Connector Realized with Quad Transition using Adequate Quad Pattern. The top, left image illustrates the initial model situation. The remaining
images illustrate connectors that have been realized with quad transition using
different quad pattern sizes: average, coarse, small. The regular quad pattern
size is highlighted and the red lines illustrate which nodes have been snapped to
a relevant feature or free edge.
For spot quad transition, automatic snapping and feature detection is enabled by
default via the allow snapping checkbox. This prevents the
creation of elements that are too small, and ensures that the geometry is not modified
too much.
Free edges and features with an angle greater than 25° are always taken into
account. If smaller feature angles should be considered, decrease the value in the
feature angle field (Preferences > Meshing Options). Feature angles smaller than 5° will not be considered.
By default, snapping is allowed by a distance of one third of the quad pattern
element size. In the case of a predefined quad pattern element size of 10.0, the outer
nodes can snap to features in a distance of 3.3. The algorithm also tries to snap all
three nodes of a quad pattern or none. Figure 8. Connector Realized with Quad Transition using Adequate Quad Pattern
A spot connector line is created when quad transition is used and a line or a node
list is selected as the connector position, unless the split to
points checkbox is activated.
In Figure 9, spot connectors are at the same exact position, though
there is a notable difference. In both images, the connectors have been created along
a line, but in the left image the split to points option was
enabled. In the left image, the quad transition pattern is aligned to the mesh; in the
right image the quad transition pattern is oriented along the spot connector line. All
elements around the spot connector line belong to the regular pattern. The number of
element pairs created along the spot connector line between the spot positions depends
on the average or selected mesh size, which can be from one to many. The quad elements
are distributed equidistant along the line.
In curved regions the inner and outer lengths of the element edges differ. Figure 9. Split to Points Example
Skip Imprint
The skip imprint option prevents the last step of quad transition from being
performed. The component ^conn_imprint is created instead, which contains the element
pattern. These elements can be modified and manually imprinted later using the
Connector Imprint panel.
Skip imprint allows you to realize such mesh-dependent realizations in very complex
areas of the model where the automatic imprint fails because of issues such as
conflicting spots. Figure 10. Skip Imprint
Mesh Dependent – Adjust Mesh – Remesh
The remesh option takes the projection points into account and uses snap and split
capabilities to connect the weld to the links. Figure 11. Mesh Dependent, Adjust Mesh, Remesh
The find nearest nodes option searches for the nearest nodes within the given tolerance
only, making it possible to connect t-joints and similar areas. This option is also very
useful in situations where the connectors are not positioned perfectly. The realizations are
allowed to be non-normal.
Find nearest node does not perform projections. Figure 12. Mesh Dependent, Adjust Realization, Find Nearest Nodes
Mesh Dependent – Adjust Realization – Project and Find Nodes
The project and find nodes option requires a valid normal projection onto the link entities
in the first step. In the second step, the nodes closest to the projection points will be
used for the connection. If the normal projection is not possible, the realization
fails. Figure 13. Failed Realization
An angle of less than five degrees is considered normal. Activating the
non-normal projection checkbox omits the requirement for a normal
projection, and permits links to only be found in the connector tolerance. The result is
exactly the same as it is for the find nearest node option. Figure 14. Non-Normal Projection
When the ensure projection option is selected, the minimum condition
for the realization is a possible projection. The realization will be performed in the
direction from one projection point to the next. If the projection point is coincident with
a shell node they will be equivalenced.
Ensure projection is comparable to the older use shell node option, which is no longer
available.
Note: Ensure projection can lead to incompletely defined connections from a
solver perspective unless the connector positions are not aligned to the mesh. The
advantage of this projection method is the exact determination of the projection
points.
Figure 15. Ensure Projection
Enabling the non-normal projection checkbox allows the realization
to be performed from one projection point to the next. Figure 16. Ensure Projection with Non-Normal Projection
