Week 12:Project-1-Meshing of Door Inner Panel Challenge

Imported file.

From the imported file we can see so many features such as Ribs, Locators etc. So that this component has different thickness on each feature.

Tools used in topology

Tools>Edge Edit Panel

A. Equivalence (multiple edges at a time) Search surfaces for pairs of free edges and combine into shared edges

B. Toggle (edge pair at a time) Select an edge; equivalences with other free edges found within a user specified tolerance

C. Replace (1 edge pair at a time) Select 2 edges to equivalence together. Control which edge to retain and which to move.

D. Geom>Surfaces>Ruled or Geom> Quick edit > filler surface or 2d> spline> surfaces only (to create missing surfaces).

In the given model there are so many defects. fillets which are very small and should be defeated. In the fig. 2.2 shows some defects.

Defeature all small fillets by using

steps

a. Geom>Defeature>surface fillets.

b. Use the Surf Fillets subpanel to identify and remove surface fillets (curved surfaces that create a smooth transition between relatively perpendicular geometric entities). You can identify fillets based on radius, because fillets are always uniform arcs. You can also select a fillet by picking one of the edges that it connects. Once found, fillets can be removed using tools that display automatically after the find process.

c. By clicking on remove all selected fillets will be removed. in the fig.2.3 shows the fillets removed by surface fillets.

Remove fillets.

Fill missing surfaces using line drag: Use the Drag Along Line subpanel to create surfaces by dragging lines or a node list along another line, called the "drag line".

Steps

a. Select the lines or node list to drag.

b. Select the lines that the drag will follow. This can also be a series of connected lines.

c. Merge the input lines into smooth lines when possible, and create a surface for each group that forms a tangentially continuous line.Clear this checkbox to create a surface for each input line, with shared edges connecting surfaces where relevant.

d. Choose where to organize the resulting surface component

3. Mid-surface extraction: The given model is a side door panel and before going to the Mid surface extraction check for thickness of entities and measure (Geom>distance). We found different thickness on each feature. For the parent we have T 2.8 units. To simply extraction of mid surface. models divided in to two components

Divided Comp.

Mid surface is done by manually using offset (Geom> surface edit> offset). offset panel shown in the fig bellow

Steps

a. select offset

b. Offset moves the selected surfaces without retaining their connections to surrounding geometry.

c . select the surface and make a duplicate of same surface

d. input the value which is half of the thickness

e. to check the direction click on vector normal so that we can see the offset direction, also one can change the direction by reverse norma

Check for direction of offset
for all ribs extraction of mid one file final edit tool from Midsurface. (Geom>midsurface>final edit tool) show panel below

Select a surface that represents one side of the solid.

Select a surface that represents the second side of the solid.

Select extraction options accordingly to define which surfaces to take into account when constructing midsurface.

By default, only two surfaces that are selected with the side1 and side2 surf selectors are considered.

To take into account offset directions of the adjacent pre-existing midsurfaces, select the use adjacent midsurfaces checkbox.

To allow modifying pre-existing adjacent midsurfaces, select the combine with adjacent midsurfaces checkbox. In the fig3.4 shows the mid for rib

4) Defeaturing: Update the Criteria length as per given element Quality criteria which is Target/Average length 5. Removing all unnecessary edges, fillet radiuses etc. also maintain distance between two edges or nodes not less than Minimum Length of 2.

tools to Defeaturing

A. Toggle edge

Left-click a free edge (red) to make it shared (green), or a shared edge to make it suppressed (blue).

Right-click a suppressed edge to make it shared, or a shared edge to make it free.

In either case, the edge must meet the criteria for the type of edge you wish to change it to. For example, toggling a free edge to a shared edge requires the presence of a similar edge within the distance you specify in the tolerance field.

B. Replace (1 edge pair at a time) Select 2 edges to equivalence together. Control which edge to retain and which to move.

C. Geom> Quick edit > filler surface (to create missing surfaces) .

Criteria

Start meshing Process by Automesh (2D>Automesh )

steps to mesh

a. Select surfaces for initial mesh and for remesh select elements.

b. select size and bias abd select mesh size which is Target/Average length 5. Use the Size and Bias subpanel to perform size and bias meshing, a flexible and powerful meshing method. A minimum of inputs are required for the element criteria settings. The algorithm options set preferences on how to handle certain situations when encountered in the geometry. When using existing finite elements as the basis for mesh generation, feature recognition settings allow the mesher to break up the areas defined by the selected elements into logical groupings with mesh controls set for each group boundary.

c. Select the type of mesh as mixed (Quad, Tria, mixed, R tria etc) and clock on alin and size in order to get proper mesh near features.

clock on mesh or middle mouse button

Modify mesh flow by changing surfaces to elements and select the elements. Make sure that while doing mesh all the element Quality criteria must be satisfied. Avid maxim opposite traits and. In fig.5.2 show the mesh flow

End point

Remove all quality failing elements by smoothing, by changing distance, angle b/w the nodes of failing elements we can see 0 elements are failed

Assigning the Thickness Property

Many features of the geometry had uniform thickness, however, some of them were having varying thicknesses. For the features with uniform thickness, a property card was created, providing it with the value of the thickness, and assigned it to the respective surfaces. And for the features with varying thicknesses, automatic midmesh thickness was provided. In the menu bar, Mesh → Assign → Midmesh Thickness, when clicked, a dialog box opens as shown in fig. 6.

Figure 6: Dialog box for automatically assign the thickness.

In this dialog box, the surfaces of parent geometry and the created elements are provided as input. Clicking the ‘Calculate Thickness’ button automatically calculates the thickness and also creates separate property cards. Fig. 7 shows the rib with varying thickness, whose thickness was provided using the automatic thickness method.

Figure 7: A rib with varying thickness.

Quality Check

After completing the meshing part, the last stage of the process is to check if all the elements are within the set criteria or not. To do that, there is an option called ‘elems check’ in the Tool section. When clicked, a window of a set of quality parameters opens. Failed elements can be found by clicking on any of the parameters. Once the failed elements are found it has to be corrected manually. It can be done by using the different tools available in 2D→qualityindex→cleanup tools, as shown in fig. 10. In this work, 6 elements have failed for warpage, 2 for skew, 8 for taper, and 49 for minimum length. All those elements are failing because of space constraints. However, there are no elements failing for aspect.

• CONCLUSION

Meshing a model is the primary and important stage of virtual testing. Thus, while meshing the geometry with quad/tria elements, attention should be given to maintain the mesh flow. Because, if it has gone wrong, the result would be inaccurate and thus would be the waste of time and money.