Prevent Intereference

[snowshelbi]

Hi,

I am learning how to use pro/e. I am using some tutorials and on one of the tutorials that shows how to connect parts a pair of mole grips is used. Evrthng is going fine but then when I was done I noticed that the parts "crossed" over each other. Is there anyway to tell pro/e to prevent such interference between parts.

Thing is, I was trying to make a geneva wheel mechanism to practice, but seeing how it relies on the driving pin on the driving wheel actually pushing on the geneva wheel it's kind of impossible to do so (unless I use an animation which I don't want to do, I want to be able to put a servo motor and then see the thing rotate on its own)

Thanks in advance.

 

[Guest0527211403]

snowshelbi

To create the geneva mechanism you need to employ cam connections between the pin of the crank and the slots on the geneva wheel (A unique connection for every slot).

Take a look at thread554-118160 for some more info on this type of connection.

Mark

 

[snowshelbi]

Hi,

thanks for the suggestion, but that's not really what I am looking for. I am more looking for an option that totally prevents bodies from interfering. Does it not exist at all or what? because I haven't been able to find anything on the net. It seems like such a basic thing to do...objects do not interfer in real life and the fact that pro/e allows them to is somewhat stupid in my opinion...so I just want to know if it's doable or not, so I can stop looking for it if it's not!

thanks

 

[mloew]

Are you talking about preventing interference as a mechanism or to ensure that parts get developed to ensure that there is not interference? These are different problems. Please clarify.


Best regards,

Matthew Ian Loew


Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[snowshelbi]

I am talking about preventing interference in a mechanism. I know that there is an option to "highlight" interfering/colliding parts and to stop the playback if desired. However, that's not what I am looking for, I want to make use of the collision of 2 parts! Basically what I am wondering is if pro/e can treat solids as, hmm, well as real solids. Like say I wanted to pin 2 rods, but instead of using a pin connection I want to use an actual pin (that would be a part) to connect them "physically". so is this doable or am I expecting too much :S ?

Also, I heard of pro/mechanica, would that be able to perform such a thing?

thanks

 

[mloew]

You will want to follow Mark's method of making sure that you have cam connections (with lift-off) between potentially contacting surfaces. You could track the maximum contact load (I think with MDO you may be able to do this) then track the time at which that contact occurs and pass the loads into MECHANICA for a structural simulation (using contact elements here). If all you are interested in the is he accurate animation of a mechanism, use cam connections.

Best regards,

Matthew Ian Loew


Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[Guest0527211403]

Pro/E does not prevent interference between solid models in a mechanism, nor is there a setting to make this happen (other than creating a cam connection).

A Pro/E "solid" is not really a solid in the way you are suggesting. It is a collection of closed surfaces that satisfies certain rules which allow the software to calculate its mass. When a solid passes through another solid, all Pro/E knows is that there are two objects taking up the same space at the same time. It is up to you, the designer, to figure out what to do about it.

Having it automatically do this may seem "basic" like you said, but you should try to write the code for that before you make such a claim. Object collisions are actually pretty complicated to analyze, and as such you need to manually specify where they occur one by one. Otherwise, Pro/E will assume that the objects are not supposed to collide, and, like you mentioned, you can analyze the mechanism to determine which solid bodies are interfering with one another.

Sometimes, you need this interference (i.e. a press fitted bearing), and if the mechanism locked up every time there was interference, it would REALLY slow down the design process.

Mark

 

[snowshelbi]

Thank you very much Mark for your reply. It answered all the questions I had

I just want to apologize if it seemed like I was saying it was an easy task to do. I know that collision is not the easiest thing to program (I made a little screen saver in C++ with "planets" that collided and the biggest part of the project was building a set of template classes to use vectors in order to nicely simulate collisions)

Anyway, once again, thanks very much for your help