Creating a fillet between an imported STL mesh component (aerofoil) and a Part (Propellor)Hub

[gaj1789107]

Using bespoke software I have created a propeller blade aerofoil which is imported into 2018 Inventor as an STL file. The file opens perfectly in an STL viewer (STL View) and I have checked that all face normals etc are correct. The airfoil opens perfectly into Inventor and is then converted into a Part by convert the mesh to a Base Feature. The propeller hub is created as a 2D sketch and revolved in the normal way and saved as a Part. The two parts are assembled into an Assembly by Placing and Constraining, with the final aim of applying a fillet around the foil/hub interface. The Assembly is then converted to a combined part before trying to apply the Fillet. See screen shots below of the Parts and assembly .

However I cannot make this work. I have tried Combining, Joining, Shrink Wrapping and Repairing etc. with no avail. Does anyone have a solution please??

[Bunny]

Based solely on the screenshot, the foil appears tessellated, which is the norm when importing an stl. For the fillet to work, you would have to select each surface individually. Can you post the parts to look at? If not, and you have access to Fusion, it has tools that can reduce the number of surfaces. Did you try the surfacing tools?

Is the stl format the only available data output from your "bespoke software"?

[gaj1789107]

Based solely on the screenshot, the foil appears tessellated, which is the norm when importing an stl. For the fillet to work, you would have to select each surface individually. Can you post the parts to look at? If not, and you have access to Fusion, it has tools that can reduce the number of surfaces. Did you try the surfacing tools?

Is the stl format the only available data output from your "bespoke software"?

Hi Bunny, Many thanks for your reply. The STL format is the only output data I can generate (easily). The propeller geometry is created from very involved aerodynamic calculations which output a whole prop blade as a just set of aerofoil ribs which change along the blade length. My own software (the besepoke stuff) links all these ribs together as a closed surface containing triangular mesh elements, so the output becomes an STL file by calculating each triangle vertex set and surface normal etc. It would be a lot of work to redo this stuff - as I am not really a proficient programmer.

Since writing my first message above I have tried doing the same thing in Fusion (having never used it before). I again have imported the mesh, converted it into a solid producing a Vrep file, as Fusion requests, with no errors. Even when trying the command to "Mend Mesh errors" there were no errors reported, so I am very sure there are no problems with the blade being a valid, closed, solid object. (After the conversion the colour of the mesh changes from a blue colour to a black/grey so I think the conversion takes place with no problem). Each blade consists of around 8000 mesh triangles so well below the 50,000 limit of Fusion. For this reason I did not go on to try and reduce the mesh using the surfacing tools to reduce the mesh. I then tried to fillet the joint - and again it does nothing. I can attempt to reduce the mesh if you think it is worth a try - but I am a complete beginner with Fusion!!!

Can I ask whether the end product will have lost resolution or detail by reducing the mesh - or is this just a tool to enable other processes to take place and the original detail can be recovered later down the line?

I am not sure what you mean when asking "could I post the parts" do you mean the file?. I would be very happy to send you the STL file of a blade if you wish, which you could try and push into the side of any random cone and create a fillet between the two.

Regards,
Geb

[Bunny]

Hi Geb.

A couple more ideas:

• In Fusion, the mesh complexity can be reduced somewhat: Mesh > Modify > Reduce. Maybe play with that to see if you can get the surface to a level that will allow a fillet to be generated

• You mentioned your software outputs the blade as ribs and surfaces. Can you extract the ribs without the surfaces? If so, perhaps those can be imported into Inventor and a usable loft can be created. The quality of the loft will depend on the rib profile. If it is a spline, you will get good results, however, if the output is line segments, the result will be tessellated, but you may be able to fit a spline to the vertices

• Can your software export a point cloud? I have used those before with various levels of success

If you want to share your data, I can take a look. Attach a zip of all of your stuff.

Thank you.