Dynamic simulation = > restitution

[Anonymous]

Hi!

I am learning Dynamic simulation = > restitution.

I use the tutorial by @JDMather 

https://www.youtube.com/watch?v=Rer-IjWzKAU&list=PLp5izJt_zvN08mpY4UcYrzJV2N6QOLAIR&index=6 

I have trouble in creating 2d contact

The assembly is attached 

Thank you.

[JDMather]

Think Fences!

Uhmm, Sketch1 of your Ball is not fully defined?

Have you gone through these Tutorials?

Sketch1 of restitution platform is not fully defined??

Sketch2 of restitution platform is not fully defined???

[Anonymous]

Hi
My questions are coming because I'm going through your tutorials right now

[Anonymous]

This is the exercise from your ---restitution  tutorial

[Anonymous]

I have set the constrains.

===

Think Fences!

+++

I didn't understand the hint)))

[JDMather]

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@Anonymous wrote:

Hi
My questions are coming because I'm going through your tutorials right now

---

In all of my tutorials the sketches are fully defined.

We better go back to the very beginning.

Attach you Revolution Joint files here.

[Anonymous]

Great!

Thank you!

I will post them on Monday

[Anonymous]

Hi!

I have attached the revol. joint files.

They are not the same as yours since I have done this from memory.

I almost  didn't have problems with that.

As I mentioned before I don't understand the concept of arrows and how to use them properly.

Thanks! 

[JDMather]

You did fully define the sketches on the parts for the Revolution Joint.

Not sure why you didn't fully define the sketches for this ball-drop problem?

Underdefined sketches should keep you awake at night.

You should not be able to eat or sleep.

[JDMather · Accepted solution]

For 2D Contact Joint you need to think in my term as "Fences" that extend to infinity.

The fence profiles must be co-planar or on parallel planes.

For illustration purposes I added a "keep-in fence to your ball drop problem.

Then I turned it sideways to illustrate next to the previous Planar Joint problem.

Note that the two problems are essentially identical when viewed as "Fences".

The only thing that has changed is the orientation of the fences.

[Anonymous]

+++++++++++++++

Not sure why you didn't fully define the sketches for this ball-drop problem?

+++++++++++++

Well, I fully constrained the sketches   I have and thought that it is enough.

I'll try to implement the "fences approach and will let you know.

 Thanks!

[Anonymous]

Yes, it works!
Thank you!

But arrows are still the mystery for me.

In this example there are 4 combinations for arrows positioning.
I have tried all of them and the  last one works fine.

I am not sure that it is a smart approach))

Could you please explain me)))

[JDMather]

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@Anonymous wrote:

But arrows are still the mystery for me.

In this example there are 4 combinations for arrows positioning.
Could you please explain me?

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No files Attached?

[Anonymous]

Here it comes

First - the table

and here are the images:

[JDMather]

Z is incorrect in both of those images.

Z should point to the outside.

The outside of your ball would be with Z pointing out.

Since you want to keep the ball outside of the "fence" the Z should be pointing out of the "fence".

(If you wanted the ball to stay inside of a "fence" the Z would be pointing inside the fence.  X and Y directions don't matter in this case.)

[Anonymous]

==

Z is incorrect in both of those images

+++++++

There are 4 different images

[JDMather]

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@Anonymous wrote:

There are 4 different images

---

I didn't see the 4th image - it is correct in that image.

The mark of a good student in the classroom who has gained understanding - would have told me that I must have missed the 4th image.

When you know you are right - you know you are right.

[Anonymous]

ok.

I have got the idea about the base,

but I still have a question regrading the ball's axis.

If I place arrow towards down it is outside of the ball

If I place arrow towards up it is still  outside of the ball

There is not Z axis which directed inside of the ball.

Is this an issue of a terminology?

[JDMather]

I think that you are getting confused by the length of the arrow (depends on zoom level).

Look at the origin of the triad.  The direction is...

[Anonymous]

ok. I got it.

Thanks