topic Re: Dynamic Simulation joints in Inventor Forum

Dynamic Simulation joints

Wapster — Fri, 22 Apr 2016 13:20:24 GMT

Hi all,

Could someone please help me explaining why, working in the Dynamic Simulation environment, IV keeps telling me that one joint is redundant in the attached assembly (open blokkeerinrichting versie 05.iam and go to the DS env.)

This assembly is made in IV 2016 !

I'm on it for a few hours now and it's getting really annoying

Thanks in advance,

Wap.

Re: Dynamic Simulation joints

JDMather — Fri, 22 Apr 2016 14:34:00 GMT

A Prismatic Joint would be a better choice.

The piston moves in a straight line, rotational DOF is removed by the lock nut.

In the real world assembly there would have to be clearance between joints.

The Point-Line allows "twisting" DOF at that joint.

Re: Dynamic Simulation joints

Wapster — Fri, 22 Apr 2016 14:39:46 GMT

Hello Jeffrey,

Thank you for replying.

You are exactly right about the Prismatic Joint.

The problem is that these joints can only be created automatically.

I cannot create an Prismatic Joint manually (or am i missing something)

IV creates the cylindrical joint automatically with the redundant warning.

If i remove the mate constrain (mate 12) the joint is gone and the warning also.

But the rod will come out of the cylinder, so that's no good.

Is there a way to manually add a Prismatic Joint ?

Many thanks in advance (still on it)

Regards,

Wap

Re: Dynamic Simulation joints

JDMather — Fri, 22 Apr 2016 14:51:25 GMT

1. Did you check the solution that I attached above.

2. If you need to manually add Joints, you can get access to all Joint types by turning off automatically conversion of assembly constraints to dynamic simulation joints (you can do this after running the automatic for most of them).

Re: Dynamic Simulation joints

Wapster — Fri, 22 Apr 2016 15:13:28 GMT

Good God......

I missed your attachment... sorry for that.

I didn't know that the all the automatically generated joints types would come available once you turned of automatic conversion.

I knew automatic conversion could be turned off, but i missed the extra joints you can pick then.

But this is the trick. Spot on.

Thank you so much for your time and help.

Regards,

Walter.

Re: Dynamic Simulation joints

JDMather — Fri, 22 Apr 2016 15:19:39 GMT

You could add a 2D Contact if you want to limit the motion of the piston.

Re: Dynamic Simulation joints

Wapster — Fri, 22 Apr 2016 16:18:35 GMT

Tried that for the past hour...

Can't get it to work. Invalid this, invalid that.

I give up

Thanks anyway

Have a good weekend

Regards,

Walter.

Re: Dynamic Simulation joints

Wapster — Sun, 24 Apr 2016 14:52:17 GMT

Hi Jeffrey,

I figured out the 2D Contact Joint (I think)

Could you confirm this is the way to go (please)

Or would you take another approach.

Thanks in advance,

Regards Walter.

Re: Dynamic Simulation joints

JDMather — Sun, 24 Apr 2016 15:31:36 GMT

I would have done slightly differently.

see attached

Note that a circle has one point of contact with a line (easy for the computer to calculate).

Re: Dynamic Simulation joints

Wapster — Mon, 25 Apr 2016 08:29:21 GMT

It all starts to make more sense now, thank you for that.

Never thought to place the circle that way

Final question (if you don't mind).

How would you apply a force?

Say i want to push something out of the way with the arm.

Would you apply the force with an External Load as I did now, or would you enable an imposed motion on the Prismatic Joint?

I'm trying to figure out the difference between the two but i don't quite get it yet.

I ordered 2 books on Amazon yesterday, from Wasim Younis (see attached).

Am i gone learn something from these?

Thanks for you reply,

Walter.

Re: Dynamic Simulation joints

JDMather — Mon, 25 Apr 2016 09:40:45 GMT

Part 1 is on FEA

Part 2 is on Dynamic Simulation.