Generate Mesh tool

This panel is used to define and create a finite-element mesh.

To access this panel, click (Mesh tab > Mesh panel > Generate Mesh).

Note: The type of mesh created (Midplane, Dual Domain or 3D) is determined by the mesh type selected at the Mesh node in the Study Tasks pane, or from the Mesh panel. Beam element mesh size is defined on the Curves tab of this dialog and is independent of the global edge length applied to the model.

Dialog elements

Remesh already meshed parts of the model

If this option is selected and you click Mesh Now, all visible sections of the model will be remeshed.

If this option is deselected and you click Mesh Now, only those sections of the model that are visible and have not been meshed already, will be meshed.

Note: Remeshing a runner section or cooling channel at a different edge length is done via the Curves tab.

Place mesh in active layer

Places the mesh layer in an active Layer pane after creation.

Source geometry type (Midplane mesh only)

Specifies the type of geometry that is to be meshed.

Note: This option is only available if your part contains NURBS surfaces.

In the Study Tasks pane, after specifying that you want to generate a Midplane mesh, in general, there are two possible tasks that the mesher can perform:

Mesh/remesh the Midplane geometry
Collapse the Dual Domain geometry to a Midplane mesh.

In most cases the mesher will know which of these two alternatives apply based on the attributes of the entities, and whether there are free edges in the geometry/mesh. Where ambiguity does exist, this option allows you to specify the type of geometry that is to be meshed.

The following settings are available:

Auto-Detect: This is the default setting. The mesher will automatically determine whether the existing geometry is Midplane or Dual Domain based on the attributes of the entities, and whether there are free edges in the geometry/mesh.
Dual Domain: Select this option to force the mesher to collapse the existing Dual Domain model geometry, that is, to midplane the model, before creating the Midplane elements.
Midplane: Select this option to instruct the mesher to create Midplane elements directly on the model geometry.

Mesh Now

Runs the mesh generation task immediately on the current machine.

Job Manager

Launches the Job Manager, where you can view and control analyses that are running.

General tab

Determines what size elements will be created when the part is meshed, that is, the global mesh density.

Note: You can experiment with different values and click Preview to see the results.

Remesh boundary: Remeshes the part surface using the target edge length.
This option is available when you generate a Dual Domain mesh for a model which already has a 3D mesh. When this option is selected, existing nodes on the part surface are ignored and the part surface is remeshed using the target edge length. Otherwise, existing nodes used by the tetrahedral elements are reused for the Dual Domain mesh.
Preview: Shows the effects of your settings on the meshing process. Edge nodes that will be generated using the set values are shown. This allows the mesh density to be reviewed before you proceed with generating your mesh.
Global edge length on surface: Enter a value to set the target mesh element length that will be used when generating the mesh.
Note: Your edge length setting may be ignored in certain areas of your mesh if the setting is not appropriate. For example, if you specify a long edge length, your target edge length will be used in straight areas of the mesh, but a shorter edge length may be used in curved areas.
Merge tolerance: Sets the minimum distance between nodes that will be targeted when generating the mesh.
If adjacent nodes are closer together than this distance, these nodes will be merged together during mesh creation.
Match mesh: Allows you to align the mesh elements on the two corresponding surfaces of a Dual Domain mesh.

Curves tab

Curves are used to model the pathway of the feed system or cooling channels. Connected straight beam elements then follow this pathway. Factors such as the diameter, type of pathway (feed or channel) and bends within the path can affect the edge length prescribed to a beam element.

The edge lengths are determined as follows:

Feed system - Edge length vs. diameter: A default value of 0.5 for the ratio of edge length to feed system diameter is used for beams with the assigned property of Runner. The larger this ratio, the longer the feed system elements will be. To prevent unrealistic values being used, the ratio used must be between 0.1 and 4.0.
Note: As the feed system is usually more critical to an analysis than the cooling system, the default edge length for a Runner beam is shorter than a Cooling circuit.
Circuits - Edge length vs. diameter: The ratio of edge length to cooling circuit diameter is used for beams with a property of Circuits. Values for this ratio must fall between 0.5 and 8.0 with the default value of 2.5
Note: As the cooling circuit is usually less critical to an analysis than the feed system, the default edge length for a Circuit element is longer than a feed system beam element.
Maximum allowed chord height vs. chord length: Straight beams are used to emulate a curve that turns, for example, through 90 degrees. Applying an edge length that is suitable for the straight sections of a feed system, could result in an inaccurate representation of the turn.; To ensure an appropriate edge length is applied, the cord height (distance 3 to 4 in the following diagram) is divided by the chord length (distance 1 to 2). The default value for this ratio is 0.05 with an available range of 0.02 to 0.3. Shortening the edge length will reduce the chord height and so reduce this ratio.; The edge length for the beams in that section of the curve is calculated so that the resulting ratio falls into the allowable range.
Gates - Minimum number of elements on each curve.: Material entering the cavity is a critical phase of the injection molding process. It is recommended that the sections of the curve that represents the gates should be modelled with at least 2 beam elements. This is the default value for this parameter which can be adjusted in integer steps between 1 and 5.

CAD tab

Allows you to set mesh parameters for CAD entities.

Chord Angle

When selected, you can control the mesh density of curved features of the model by defining a chord angle.

Chord Angle Slider Bar

Sets the chord angle constraint to be used when meshing curved features.

Chord Angle Graphic

The effect of altering the chord angle is represented by the smoothness of the illustrated circle.

Note: A fine mesh will significantly increase the resulting number of elements.

Tolerance

When meshing using a chord angle, the Tolerance option allows you to manually set the chord angle to be used or review a Chord Angle slider setting.

Note: A small chord angle will increase the number of elements significantly.

Percentage of minimum curvature size with respect to global size.

This control defines the default minimum chord length in relation to the specified global edge length. This can be defined by the user. The default is 20% of the global edge length.

Note: Reducing the Percentage of minimum curvature size with respect to global size could significantly increase the number of elements.

Growth rate

The gradation of the mesh, from the finer elements around a small feature to the larger element size as defined by the global edge length, can be controlled by the Growth rate. The range of values that can be entered is between 0 and 1.0. A Growth rate of 0 has the more gradual transition, while a value of 1.0 has the fastest change. The number of elements in a model as a result of changing the growth rate is model dependant.

Mesh on assembly contact faces options

There are three options that can be used for meshing assembly contact faces.

Precise match: When the CAD model assembly has no geometric errors in the contact areas between components, there will be a precise duplication of nodes and elements that are on the contact surfaces.
Fault tolerant: With the Fault tolerant option, small variations in the CAD model are compensated for, and the mesh is aligned where possible.
Ignore contact: The assembly components are meshed without considering surface contact. If there is significant mismatch between the contact area meshes, the contact area nodes may need to be manually aligned.

Sliver Removal

When selected, slivers (small elements with a high aspect ratio) will be removed from the mesh.

NURBS tab

Allows you to match a Dual Domain mesh or smooth a Midplane mesh to assist post-processing after analyzing the model.

Note: Click the Post processing check box, and then select either Match mesh or Smooth mesh.

NURBS surface mesher

Specifies which meshing technique should be used to generate the mesh on imported Non-uniform Rational B-Splines (NURBS) surfaces.

The following options are available:

Advancing Front: This meshing method first places nodes on the boundary of surfaces, then creates nodes in the interior and creates elements using those nodes. This method requires more computational time than the regular meshing method, but generally gives better meshing results for curved surfaces, in particular when used in conjunction with the chord height control option.
Legacy: This meshing method first places nodes on the boundary of surfaces, then creates elements, working inwards from the boundary to the center of the surface. This method is faster than Advancing Front, but is not recommended for models with fillets and other highly curved surfaces.

Enable chord height control

Increases the chance of creating a mesh that closely corresponds to curved surfaces.

Without chord height control, some surface curves, such as fillets, degrade when meshed. Chord height control is effective only with parts that have curved surfaces.

Tip:

Keep the value of the chord height somewhere in the range of 5-25% of the global edge length. If the value is below approximately 5%, the resulting mesh tends to contain several long and/or thin triangles. If the value exceeds 25%, the chord height control has little effect.
If matching your (Dual Domain) mesh is a higher priority than getting a good curved mesh, use the edge length control instead of the chord height control. A small edge length gives you a mesh that matches well and closely corresponds to curved surfaces.

Optimize aspect ratio by surface curvature control

Adjusts the size of the mesh to the local curvature on NURBS surfaces automatically.

Optimize aspect ratio by proximity control

Detects proximities between boundary curves automatically, and ensures adequate mesh refinement at locations where boundaries are close to one another.

Smooth mesh (NURBS surfaces only)

Allows you to smooth the edges of a Midplane mesh.

Tetra tab

Sets the minimum number of elements and maximum aspect ratio that Autodesk Moldflow Insight will use to generate the 3D mesh.

3D Mesher

Specifies which meshing technique should be used to generate the tetrahedral mesh.

The following options are available:

Advancing Front: This meshing method benefits from a better control over the size of the elements than the legacy method. It generates more elements in corners and transition regions, and it minimizes the generation of dense node patches on the surface.
Legacy: This is the meshing method used in previous releases.

Minimum number of elements through the thickness

Sets the minimum number of elements through the thickness that will be targeted when generating a 3D mesh.

The typical number of elements through the thickness is 6, but critical analyses may require more layers. To properly analyze a gas-injection simulation, a minimum of 10 layers is recommended.

Tip: Increasing the number of elements through the thickness increases the total number elements, which increases computation time. Despite increased computation time, it can be worthwhile to increase the minimum number of elements if you have a very thin part and you need an improved temperature solution. Check that the resultant Aspect Ratios are acceptable and decrease the Global edge length on surface if required.

Ratio of maximum tetra edge length in thickness direction to global edge length

When the global edge length is altered, the maximum tetra edge length is automatically adjusted to maintain the required ratio

It is advised to use a ratio between 0.4 and 1.5.

Tetra aspect ratio control

Allows both automatic ratio control and a manual setting for maximum allowed aspect ratio.

Automatic optimization: Produces a mesh with smaller aspect ratios and less elements in most instances. It is recommended that this be left on unless meshing problems occur.
Maximum allowed aspect ratio: Sets the maximum aspect ratio that Autodesk Moldflow Insight will aim for when it generates your 3D mesh. The typical aspect ratio is 15, but values up to 50 are reasonable. The manual setting uses a more conservative algorithm and is not recommended unless errors are found using the automatic function.
See also Aspect ratio

Tetra Advanced tab

Moves and distributes nodes in order to reduce the aspect ratio of generated tetrahedral elements when generating a 3D mesh from a Dual Domain mesh.

Use surface mesh optimization

Creates a mesh with fewer high aspect ratio elements. This option is on by default and should only be deselected if the quality of the surface mesh suffers.

Use surface mesh matching

Specifies that a uniform volume mesh will be created, aligned through the thickness with the elements on the top and bottom of the surface initial Dual Domain mesh. For very chunky parts, there is often little value in matching the Dual Domain surface mesh. For these parts, de-select this option and a 3D mesh will be generated with a different algorithm that does not rely on the surface mesh.

Node biasing through thickness

Allows you to adjust the relative thickness of each element layer in a 3D part. This is achieved by shifting the node layer closer to either the surface or the center of the part.

When node biasing is applied, the number of element layers and nodes through a part's thickness is still the same, but the local thickness of each layer will be changed.

Even distribution without biasing

Nodes are distributed evenly through the thickness. This is the default option.

Bias ratio

The ratio of the thickness of an inner layer vs that of an adjacent outer layer.

For example, if the ratio is greater than 1, outer layers (close to the surface) will be thinner, and inner ones will be thicker. Consequently, the node density near the part's surface will be higher than that near the center.

Conversely, if the ratio is less than 1, inner layers will be thinner than outer layers and the node density near the center of the part will be higher than near the surface.

Enter a number between 0.5 and 2.

Mesh smoothing

Select how existing nodes should be distributed in order to smooth the mesh.

None: Nodes are not moved at all during meshing. This may lead to elements with a high aspect ratio.
Smooth all nodes: Interior nodes are moved if doing so can produce elements with a lower aspect ratio.
Skip aligned nodes: Interior nodes are moved if doing so can produce elements with a lower aspect ratio, but not if the node is already aligned with another node across the part thickness.