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Simulation of movement using contact regions

agessner

New member
Hi,

I'm using Mechanica Motion to simulate movement by using contact regions between the surfaces, but everything I get is information, that

Pro/MECHANICA cannot proceed with the analysis because it could no open the geometry model database needed for contact regions or clearance measures.

Anybody could help me?

Thanks in advance

Andrew
 

agessner

New member
Thanks for Your answer amd450. I was becoming hopeless if someone would help me.

I am using PRO/E Wildfire with Mechanica in integrated mode.

That's the model I am currently workin on. It is not the case, which mostly interests me, but I've just started using Mechanica, so I have to learn using simple things.

The model consist of three parts: frame, rod and something like cam. I put a pin contrain between the frame and rod, so the rod can go up and down. Then I used a contact region to model the mating of rod and the kind of cam, and I put a driver on the axis of cam.

I know, the mechanism is not a proper substitut of a cam-follower, but as I wrote I did not want to simulate cam-follower, but something else, and this is just an example I am using to learn.

So after I try to run a motion analysis, the Mechanica gives me the information I put in the prior post.

Incidentally I am going to simulate mating of a spiroid gear, so that's why I need to know how to set it properly.

I would be glad if You could tell me what's wrong.

Thanks

Andrew

View attachment 388
 

Israr

Active member
If you send me the files I will do it for you. You do it using Mechanism Design (you need MDX or MDO license) and the connection you need is slot follower.



Israr
 

Luis Aguirre

New member
Hello Andrew,



Contact analysis using motion is very tricky and unless you are looking to find what forces are generated during IMPACT using contact analysis is not the way to go. In fact, the contact functionality has been removed from MDX all together and with Pro/MECHANICA MOTION been retired with Wildfire 2.0 who knows when PTC will add the contact functionality back in MDX. Any way, here is what I think your problem is, Contact analysis is motion uses Hertzian contact theory for analyzing the contact between the parts. In a nut shell only perfect spheres, cylinder and planes are allowed to contact. I believe as is done in FEA the software looks for the normals of both surfaces that are in contact and finds out if they are penetrating (clearance measures) if your geometry is not perfectly flat or simulates a sphere or cylinder motion will have a hard time processing the geometry for the hertzian contact analysis that needs to have to proceed with the solution. Here is one thing you might want to try assuming that your geometry meets the hertzian contact conditions. You may want to increase the accuracy of each individual part and assembly to see if solves the problem. Otherwise, as I mentioned before unless you are trying to find out impact forces you may want to use the cam/slot follower functionality since contact and motion are no longer available in Wildfire 2.0.



Luis
 

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