topic Imported .step file in Simulation Mechanical appears distorted in Fusion Support Forum

Imported .step file in Simulation Mechanical appears distorted

sanziana_moldoveanu — Mon, 21 Oct 2019 06:42:54 GMT

Hi! I am having an issue with an imported .step file from Fusion 360 to Simulation Mechanical. I don't know where the problem lies if it's in one or the other program. I will attach a photo so you have a better idea of what it's happening. Basically I reconstructed a mandible section using sketches and loft command and then split the body to model the implant site. Then exported as a .step file and imported in Simulation Mechanical. The model appears just fine in Fusion 360 but appears distorted in Simulation mechanical. What do you think is the problem?

Re: Imported .step file in Simulation Mechanical appears distorted

TheCADWhisperer — Mon, 21 Oct 2019 11:36:30 GMT

Change the threads to cosmetic.

Can you point to any reference that recommends using modeled threads in any analysis software?

There might be other issues going on here - but that is where I would start in idealizing the geometry for analysis.

Can you Attach your *.f3d file here?

Re: Imported .step file in Simulation Mechanical appears distorted

sanziana_moldoveanu — Mon, 21 Oct 2019 13:31:10 GMT

Thanks for the response!

Unfortunately, I need to have a modeled thread. The thread of the implants positioned has a special design.

I have read about the pros and cons of cosmetic and modeled threads but for this project, I can only use modeled threads.

https://caeai.com/blog/detailed-modeling-threaded-connections

I have attached just the part with the problem. Can you think of any other solution? I feel like it's a glitch that happens sometimes because I had this problem before and I just moved a bit the implants, resplit the bodies and voila, it worked! I have tried this method this time but no luck.

Re: Imported .step file in Simulation Mechanical appears distorted

TheCADWhisperer — Mon, 21 Oct 2019 13:45:05 GMT

I have just started experimenting with this - first thing I would do is move to symmetry about the origin.

I have seen unexpected results in multiple CAD softwares when object is a long distance from the origin.

It doesn't appear excessive in this case, but I would move and check the export again.

Re: Imported .step file in Simulation Mechanical appears distorted

TheCADWhisperer — Mon, 21 Oct 2019 14:00:32 GMT

It will be a while till I can get back to this - but I ran a Quality Check in other software and found two issues.

Re: Imported .step file in Simulation Mechanical appears distorted

John_Holtz — Mon, 21 Oct 2019 19:37:16 GMT

Hi @sanziana_moldoveanu

Have you tried any of the other formats that are common between Fusion and Simulation Mechanical, such as Inventor files, IGES files, or SAT files? Perhaps one of those formats will work better.

What I see in Sim Mech is that some of the spiral surfaces along the threads are not coming in properly or are not meshing. So perhaps it will work (or work better) if you split the threads in half -- either into left and right halves or top and bottom halves. Instead of having one surface on a spiral that makes 3 or 4 complete turns, maybe a spiral that makes a half turn (split left-right) or 2 turns (split top-bottom) will work.

Re: Imported .step file in Simulation Mechanical appears distorted

sanziana_moldoveanu — Wed, 23 Oct 2019 05:28:53 GMT

I have moved all the parts close to the origin but still, get the same distortion. In regards to your second post, I think that one is too advanced for me.

Re: Imported .step file in Simulation Mechanical appears distorted

sanziana_moldoveanu — Wed, 23 Oct 2019 05:32:06 GMT

I exported as a .IGES file and it actually crashed my Simulation Mechanical program but .SAT worked perfectly and did not distort parts. So I guess .SAT is the way to go. For now it works. I will report back if I have any more issues! Thanks a lot guys!