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Fillet operation

Alexander Chernyadiev

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Hello to everyone! My name is Alexander, a master degree student at ITMO University, Saint Petersburg.

Currently I am working with golden nanotriangle structures. I don't want my structure to have any sharp edges. That's where I have encountered an issue. I have managed to fillet all 6 edges along all 3 sides of the triangle (at the top and at the bottom) using Boolean operation "difference" and working in different workplanes in 3D (see the image). But I struggle with filleting edges connecting the upper and the bottom face together (vertical edges). If I create another workplane (xy-plane), draw the same triangle (polygon command), fillet its vertices, draw a square around this triangle, use a difference command to subtract the triangle with rounded edges from the square, extrude the workplane (see the image after extrusion), and THEN try to use difference again subtracting this extruded object from my initial triangle I won't get rounded vertical edges but a notification that the output object is empty. I don't understand why this is happening. Can someone please help me out? Any advice or suggestion will be truly appreciated!

I have tried many different things solving this problem, but none of them worked. I tried filleting vertices first and extruding my triangle and THEN filleting edges along sides with boolean operations but received the same notification. Though in that case I managed to fillet the edge adjacent to the upper face of the triangle and received that notification only when dealing with the edge adjacent to the bottom face. I didn't find solution in the Internet. In addition, I know that this problem is easily solved with a Design Module where apparently one can do 3D fillet operations but I don't have a license for it. I'd like to resolve my issue without using the Design Module. I am using 5.2a version of COMSOL.

Finally I attach 2 images of the structure and the project itself. Thank you in advance! I apologize for a long description but I tried to state clearly what I am trying to achieve. Best wishes, Alexander



2 Replies Last Post 08.03.2019, 11:02 GMT-5
Jeff Hiller COMSOL Employee

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Posted: 5 years ago 06.03.2019, 13:33 GMT-5
Updated: 5 years ago 07.03.2019, 04:27 GMT-5

Hi Alexander,

For this particular geometry, you may be able to get it done by taking boolean operations on a bunch of spheres (for the corners), cylinders (for the edges) and extrusions. Those kinds of approaches only work for very specific cases, but for you that may be all you need. In the more general case, where the edges to be filleted can be curved for instance, or where the fillet radii are not all the same so they connect in complex ways, the Design Module is of course the recommended approach, as you've figured. Even for your case, there would be a clear benefit to using the Design Module, as you could get all those fillets done in a single step; see the attached screenshot or, better yet, the gltf file attached which you can open with, for instance, this free online viewer.

Best,

Jeff

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Jeff Hiller
Hi Alexander, For this particular geometry, you may be able to get it done by taking boolean operations on a bunch of spheres (for the corners), cylinders (for the edges) and extrusions. Those kinds of approaches only work for very specific cases, but for you that may be all you need. In the more general case, where the edges to be filleted can be curved for instance, or where the fillet radii are not all the same so they connect in complex ways, the Design Module is of course the recommended approach, as you've figured. Even for your case, there would be a clear benefit to using the Design Module, as you could get all those fillets done in a single step; see the attached screenshot or, better yet, the gltf file attached which you can open with, for instance, this free online [viewer](https://gltf-viewer.donmccurdy.com/). Best, Jeff


Alexander Chernyadiev

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Posted: 5 years ago 08.03.2019, 11:02 GMT-5

Hello!

Thank you very much for your advice about the union operation. After a few hours of work I have managed to create the desired geometry. I attach the project with created geometry to this message in case anyone will make any use of it.

Best wishes, Alexander

Hello! Thank you very much for your advice about the union operation. After a few hours of work I have managed to create the desired geometry. I attach the project with created geometry to this message in case anyone will make any use of it. Best wishes, Alexander

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