Geometry Cleanup and Meshing of 2d Shell element models using Hypermesh

Objective:

1.To clean the geometry

2.To extract the midsurface out of the given geometry

3.To cleanup the midsurface

4.To make necessary changes as required for achieving a better model

5.To mesh the model maintaining the given range [3.5:5:7]mm as required and assigning appropriate thickness and property

Procedure:

Part1:

Step 1: Open the Hyperworks Student edition and from the menu File>open>model

Step 2: Check for the free edges and multiples surfaces by changing the Geometry colour mode from Auto to Mixed. Free edges(red) are the surface dicontinuities in the model. Multiple Surfaces(yellow) are the surfaces that overlap with the adjacent surfaces

Step 3: Go to Geom>surface edit>trim with surf/planes>with surface, Click Trim

Step 4: Delete the surface after surface trim by Pressing F2 or clicking the delete on the toolbars and select the surface.

Step 5:Press F11 or follow Geom>quick edit>filler surface select the required surface as shown below and the surface gets filled and turns green indicating no free edge.

Step 6: Replace points with the one we want to change with the point we want to retain by pressing F11 and selecting the replace point with the one to be retained.

Step 7: Press F11>Toggle edges check other red (free) edges try toggling them if they change, click return, if not increase the tolerance and then try toggling again.

Step 8: There are two surfaces which share multiples surfaces with their adjacent surfaces so press F2 and select surfaces and click delete so that the surfaces gets deleted.

Step 9: Cleaned Geometry

Step 10: Now Extract the Midsurface by toggling Geom>midsurface.

• Make sure to check the auto midsurface and closed solid.
• Select the surfs>displayed or all and click extract.
• A midsurface will be generated.

Step 11: As mentioned in the objectives of the assignment the holes with less than 5mm besides to this surface fillets with less than 2mm can also be removed so that the quality index obtained will be better.

• Go to Geom>defeature>pinholes.
• Select surfs>displayed.
• Select Pinholes>displayed and make sure change the diameter to <5mm and click find and delete the pinholes.
• In the same way select Surf fillets>surfs, find fillets in selected>surfs>select the surfaces to be removed, change the min radius to 2mm. Click find and remove the surfaces. (This can also be done by selecting the lines).

Step 12: Press F12 for automesh or go to Geom>automesh>density make sure to change the element size as 5mm and click mesh.

• If the mesh is Wavy and if there are any messy regions where the mesh deviates than required, toggle from density to mesh style.
• Set the element type to quads
• Set the mesh method to map as rectangle
• Toggle on align and toggle off size and skew and mesh again
• Mesh can also be done to some elements by changing from surfs to elements and then selecting respective elements that are of interest and click mesh.

Step 13: Check the quality index by going to Geom>quality index

Step 14: Renumber the elements if needed by toggling on the tool page Tool>renumber>elements>displayed.

• set the start with to 1
• set the increment by 1
• Click renumber and click return
• Go to Geom>numbers>change from nodes to elements>toggle display>click on return

Step 15: Now thickness and property is to be assigned to the original component from where the midsurface is generated for this,

• Go to tool page Tool>organize>toggle on collectors> select the destination component to Ivl10 as stated in my model>elements>displayed or all>click move and return.

• Assign the thickness to the model and property by right clicking on the mouse button at the property > select edit and give the thickness to the material.

Till now the procedure for performing midsurface generation, pinholes and surface fillets deletion and meshing has been done.

Now the interest is to show some more features of how meshing is done using reflect and position for the rest two models.

The procedure for only the required methods will be discussed as the main procedure has already been given in the Part 1.

Part 2:

Step 16: The geometry clean up has been done for the part 2 by using the remove points feature and retaining the required points.

Step 17: Midsurface of the model has been extracted

Step 18: Meshing the model, before that add a washer split by selecting the circle for which the washer split has to be added. Press F11 or Geom>quick edit>washer split and give some offset value to it.

Step 19: Reflect the side surface mesh by going to Tool>reflect and by selecting the elements that are to be reflected and then selecting the nodes N1,N2 and N3, click reflect.

Step 20: Position the mesh to the other size by Tool>position>select elements>select nodes(from and to) and click position.

Step 21: Check for the unconnected elements by pressing SHIFT+F3 and then select the elements and then check for different tolerance value, click preview equivalence and then press equivalence.

Step 22: Check the quality index of the mesh

Keeping the mesh to be consistent and maintaining the target element size is the criteria so this is quality index after few iterations that have been performed. There are no holes with less than 5mm diameter.

Step 23: Mesh with thickness and property assignment.

Part3:

Step 24: Geometry cleanup

Step 25: Midsurface Generation

Step 26: Mesh Generation ( There are no holes with less than 5mm dia, so no need to take filler surface)

Step 27: Mesh Quality index

Step 28: Assigning Thickness and property

Conclusion:

Mesh has been generated for all the three given parts. It is understood that there is scope for better quality of the mesh. But the main aim is to understand How to

• Clean the geometry
• Generate mesh
• Different features to obtain a mesh
• Smooth a mesh with mesh style and with elements and
• Check the Quality index and to assign property and thickness