Hypermesh - Project 2 - Meshing of Floor Mesh Panel

OBJECTIVE

To mesh the given floor panel geometry through after generating its midsurface. To also ensure that mesh is of the highest quality (following given quality criteria) with a low number of trias and good mesh flow.

CAD MODEL IMAGE

The floor panel geometry:

QUALITY CRITERIA

Target Element Length = 5mm

PROCEDURE

1. First thing to do is to make sense of all the collectors, which this component has several of. We can combine all the collectors into one by moving all of them to the first collector and then deleting the empty ones. This will help prevent any prospective confusion. This is done using the 'organize' tool (Tool > Organize). We need to select the surface that needs to be moved and the destination surface and we can go ahead and click move.



Next, we can create a new collector and we'll name it 'Midsurface' from the collector menu by right-clicking and selecting create > component.



2. Since the entire component has almost the same thickness, we can go ahead and generate the midsurface manually from the bottom. This is due to the complexity of the geometry in certain regions. For this, we will need to measure its thickness. Which is 0.75 mm. (Thickness tool can be accessed by pressing F4). We need this for the manual creation of the midsurface. And this is done using the offset tool under surface edit.

3. Before carrying out the next step, we need to ensure that the newly created midsurface component is our current component. (We can make a component the current one by right-clicking the particular collector and selecting the 'make current' option).

4. The offset tool requires a measurement half of the thickness. Which would be 0.375 mm in this case. The offset tool can be accessed through Geometry > Surface Edit > Offset. We can select any one face from any one of the faces. And then, right-click surfaces and select 'by face'. When this is done, the entire face is selected (which would be the entire bottom surface of the floor panel). Not the entire component.

We can verify the vector normal too by clicking the vector normal as shown in the picture. This lets us know the prospective direction of the offset. We can reverse it if it is in the opposite direction using the 'reverse normal' option.

The following screenshot shows the 'duplicate' and 'by face' options that are required for this step.

After this, we can select 'duplicate' by selecting surfaces again. And now, we can select 'current component'. The bottom surface of the component is now transferred to our newly created component. But we are yet to offset the face.

For that, we can click offset. We now have our midsurface generated onto the newly created component.

6. As can be seen in the above screenshot, there is some cleanup that is required (free edges have appeared and are marked in red). We can make use of the toggle tool to stitch up gaps between surfaces. That will be the reason for most of the free edges seen here. Toggle option can be accessed through Geometry > Quick Edit > Toggle Edge. One of the free edges is then clicked to stitch the gap.

7. i. After cleaning up the midsurface and before meshing, firstly, the quality parameters are entered in the criteria file settings (Preferences (Toolbar) > Criteria File Settings).


ii. As is customary with meshing, we should start meshing from a certain region and work our way from that region (preferably one with more free edges). To help with this, we can make use of cut lines (quick edit > split surface node) to split the surface into smaller surfaces for better mesh control. The automesh tool can be accessed from the 2D set of options. The target element length being 5 mm.


iii. Additionally, we need to toggle lines that would hinder mesh flow and use our best judgement to make sure that the surfaces we create do not encourage tria formation (like pointed edges).

iv. After the mesh is created, we can clean the mesh using various tools. Primarily, we will be using the element optimize tool, the drag tria tool and to an extent, the swap edge tool. These are accessed from the quality index section in the 2D menu. Also, after dragging trias, smoothing will be required. It can be accessed through 2D > Smooth.

Element Optimize: The failing element is just clicked and the algorithm fixes it.


Opposing trias are dragged towards each other and removed. Then the affected regions are smoothed:

v. After we take care of each surface (meshing and cleaning up), we can move onto the next. The process is repeated until we mesh the entire component.

8. To save time and since some regions of the component are symmetrical, we can make use of the reflect tool to create the other symmetrical half (Tools > Reflect). We will need to select the elements to reflect first. Do take care not to select regions that are not otherwise part of the other half, since both halves may not be completely symmetrical. And then we can select the axis on which we are reflecting and then the base point. After that, we need to right-click 'elements' in the reflect toolbar and select duplicate. And then we can click reflect. This will create the mirrored half of the current component.

9. We will now check for equivalency by going to the edges section in the tools menu and previewing equivalence for varying tolerances (ranging between 0.2 mm to 2 mm). This is to ensure there are no misaligned elements or free edges, which we can also check using a different option in the same section. The preview equivalence option shows us the nodes that require equivalencing. They are rectified by clicking the 'equivalence' option in the menu. If some nodes haven't been tended to, it may require manual fixing, using the replace node option (F3).

The equivalence tool showing disconnected elements. They can be equivalenced by clicking 'equivalence':

10. After equivalencing, we can check for duplicates through the check elements tool in the same menu. If duplicates exist, we can click 'save failed', move on to the tool menu, select the 'delete' tool, select elements, right-click 'element' and select retrieve and then click the delete button. This should handle the duplicates.

11. Finally, we can assign a thickness for each of our midsurface, which is 0.75 mm. We can do this by right-clicking and creating a component in the component tree. After a property is created (and named 'Thickness'), we can go to its section in the bottom left and scroll down to assign the aforementioned thickness.


Then we can assign the thickness by selecting the midsurface, going to its properties box on the bottom left and assigning a property, by selecting the thickness property.

The material is also created in a similar manner, by right-clicking the collector menu and selecting 'create' and then 'material'.


We can go ahead and name it steel and assign the property to the midsurface in the entity editor section in the bottom left (as shown in the following screenshot). The property will need to be selected for it to be assigned.


FINAL MODEL IMAGES:






Some elements were invariably going to fail due to it being unavoidable to mesh surfaces with tight dimensions. They could have been toggled to avoid this issue but that would affect the surface capturing. So they were meshed as is.

RESULTS

Therefore, the given floor panel was meshed after its midsurface was extracted. Meshing was carried out as per required quality criteria and it was ensured that the mesh flow was as smooth as possible. There were failed elements due to having to ensure proper surface capture.

Thickness and material were also assigned to the midsurface.