Community
Inventor Forum
Welcome to Autodesk’s Inventor Forums. Share your knowledge, ask questions, and explore popular Inventor topics.
cancel
Showing results for 
Show  only  | Search instead for 
Did you mean: 

Sliding joint restriction in dynamic simulation

4 REPLIES 4
SOLVED
Reply
Message 1 of 5
Roger456
832 Views, 4 Replies

Sliding joint restriction in dynamic simulation

Hi

 

I have an issue with a sliding joint in a simulation and I have attached files to explain it. Here we have a very simple box with a cylinder that slides around a closed loop curve. The curve as you will see is described by two circles and one elipse that all overlap to give a smooth closed loop. In the assemble this all works fine - you can freely drag the cylinder around the curve. However in dynamic simulation when I try to insert a 'sliding cyclinder on curve' joint I get the message that only lines, arcs and splines can be used for a curve. If I change the elipse to another circle then I don't have this problem. So is Inventor restricted to arcs of circles rather than arcs of elipses? Is there a way around this?, Do have I have to draw the whole curve as a spline?

 

Thanks

Roger

4 REPLIES 4
Message 2 of 5
henderh
in reply to: Roger456

Hi Roger,

 

  I think you're correct that in this case, a spline profile for the ellipse is the only viable option.

 

  If we create a spline through four quadrant points from your original ellipse, we can get very close using the 'minimum energy' fit method of the spline.  DS won't complain creating or simulating the sliding joint.

 

  Hope this helps...

 

-Hugh

 

DS_Roger456.png



Hugh Henderson
QA Engineer (Fusion Simulation)
Message 3 of 5
Roger456
in reply to: henderh

Hi Hugh,

 

Thanks for clearing that up. I can see how I can get around this now. I do have one more related question though. If you notice in my original box part the extrusion is not just of the ellipse, I extrude the shapes from the intersection of the ellipse with the other three circles. Those circles have tangent constraints between them to make the intersections smooth. I was hoping I could draw all the circles and ellipses as splines but it appears that it is not possible to have tangent constraints between these? Just to try and make my explanation a bit clearer I have attached a simple sketch which shows two circles with tangent contraints on the left and two circles drawn as splines on the right..but I can't create a similar tanget constraint between them.

 

I can see how I can get around this my drawing everything as circles and ellipses and then manually tracing over the desired curve with a spline with many points but the result isn't perfect. Being able to draw everything as splines would get around the problem

 

Any ideas?

Thanks

Message 4 of 5
Roger456
in reply to: Roger456

ok I made a little progress on this myself. If I convert the splines to control vertex splines then I can apply tangent constraints..but the splines distort horribly. Just trying to find a way now to fix the control vertices....

 

Roger

Message 5 of 5
Roger456
in reply to: Roger456

ok. I managed to get there in the end. It's a case of dimensioning the control vertex splines angles and sides and then the tangent constraint works fine. A bit long winded but I should be able to automate the dimensioning through VBA

 

Thanks for your help

Roger

Can't find what you're looking for? Ask the community or share your knowledge.

Post to forums  

Autodesk Design & Make Report