Drive constraint

[Chriske]

Hi guys,

 

I'm working on a Stirling engine and would like to show the spectators the priciple of that engine. It could perfectly be done if multiple Drive constraints can be done. Possible...?

 

Here's a picture :

 

 

I wanted to add a movie, but I need to post at least 9 posts before I can do that, so sorry I cannot give you more info.

Purpose is to have all rotating parts in action at the same time.

I've tried to do that through a ipn but I it did not work.

 

One last thing, I use Inventor 2008 pro

 

One last effort to add the movie : use the same link as the picture but add WC-helicopter-2.mpg instead of the jpg picture.

 

thanks in advance,

 

Chris

[shift1313]

Hey chris. One way you can get everything to move is to use Dynamic simulation. This was added in 07 i believe so you should have it at your disposal. You will need to add joints that define interactions between parts but you would only need to "drive" one thing with a torque and everything else should move accordingly.

 

Does everything move in your assembly file when you rotate the blade?

[kencaz]

You can drive multiple constraints in Inventor Studio.

 

KC

[Chriske]

Hi,

 

Only the the upper piston, crank and 1 gear are moving together.

I was hoping to have the other parts linked also.

 

Thanks for the quick reply, I'll try using Dymamic simulation. I've already read some tutorials about it . From what I read this far, not very easy to do...

 

Thanks,

 

Chris

[Chriske]

OK guys,

 

There is something I got to know before I start this.

 

When en why do I use

 

1- ipn file

2- Inventor Studio

3- Dynamic simulations

 

..to make me a small animation. What is the difference between these three;

 

Thanks,

 

Chris

[kencaz]

ipn will animate parts in an assembly, but not driving constraints...

 

Studio will animate driving your constraints.

 

Dynamic will simulate movement in real world similar to contact sets.

 

I would again recommend using Studio for simple animations using constraints.

 

KC

[MarkFlayler]

Here is some quick ref material I had from a class I did two years ago. Might help you keep the distinction or ask more questions.

ML311-3 LIG-Errata.pdf

[Chriske]

Thanks again guys,

 

I'll go for Studio indeed.

But first I need to finish some more parts and assemblys before I can start making that animation.

I completely have to redesign that Stirling engine. In the original engine no ballbearings were used at all. I'm planning to have it run as light as possible. It has to run on the warmth of a single candle only...! It'll be a chalange, but that's part of the fun...

It'll be build by my students next schoolyear.

 

Thanks again,

 

Chris

[Chriske]

...and thanks for that pfd file Mark, it was clear as mud...

[shift1313]

The nice thing about dynamic simulation in this case is frictional loads between components. The pdf document was listing differences between different approaches. With dynamic simulation you very much need to know the interactions between everything. In Studio you tell the components exactly what to do, regardless of actual physical relations. If in your assembly you activate contact solver and only have constraints for rotational components you can see how things interact(very cpu intensive).

[JD Mather]

From what I can see - shouldn't this thing work from one drive constraint? I don't see why multiple constraints would need to be driven.

[kencaz]

Your right JD. If everything is constrained properly, you could drive everything with a single angle constraint.

 

KC

[Chriske]

Hi,

 

There are two separate systems in a Stirling. In this case there's no connection between these two. So I doubt it one angle constraint will do the job (correct me if I'm wrong please) The air of the warm cilinder pushes the cold cilinder around, so there is no mechanical link at all.

 

 

Chris

[JD Mather]

Forget about the air for a minute. Drive the shaft instead with an angle constraint. (if it bothers you think of it as the flywheel inertia driving the model as it slows)

[Chriske]

This engine has been built last year by one of our students.

Here the two ciinders are mechanicaly connected, so there was o,ly one action required to have this one started in Inventor.

And yes JD, I will forget all about the air...:wink:

 

 

 

As soon as I have 9 posts I'll post an animation

 

Chris

[Chriske]

http://gti-duffel.be/6MT/Stirling-6MT.MPG

 

as promised...

Only one angle constrained was needed here to have all the parts running at the same time.