topic Re: Spinning top dynamic simulation in Inventor Forum

Spinning top dynamic simulation

sbjs7608 — Mon, 10 Aug 2020 09:00:25 GMT

Hello, I am a mechanical engineering student at Hanbat National University in Korea.
What I want to do is a simulation of applying a load to one side of a spinning top at constant speed.
Assuming that the time it takes to reach the constant velocity is 5 seconds, the time I want to apply the load is after 5 seconds.
I've tried it myself, but the simulation seems wrong.
I am wondering what part is wrong, and is there a way to make the load act after 5 seconds?
Also, I would like to upload the Inventor assembly file directly, but the capacity exceeds 71mb, so I can't upload it.
How do I attach my own assembly file?
Thank you.

Re: Spinning top dynamic simulation

JDMather — Mon, 10 Aug 2020 10:19:47 GMT

Zip and then Upload the assembly to http://myhub.autodesk360.com and then post link here to the zip file.

Re: Spinning top dynamic simulation

sbjs7608 — Mon, 10 Aug 2020 11:59:33 GMT

Thank you

https://a360.co/3fGHG9X

Re: Spinning top dynamic simulation

JDMather — Mon, 10 Aug 2020 12:39:52 GMT

Something is wrong here.

The total file size should be very small.

~~Your images do not show the browser.~~

How many parts do you have in the assembly?

Can you Attach only the *.iam file and only the Spinning Top.ipt file here?

Let's start with only the *.iam file.

Re: Spinning top dynamic simulation

JDMather — Mon, 10 Aug 2020 12:40:38 GMT

If you did a Pack and Go, you can

Skip Libraries

Skip Styles

Skip Skip Templates

What I was expecting is

1. Base.ipt (whatever you named it)

2. Spinning Top.ipt (whatever you named it)

3. Spinning Top Assembly.iam (whatever you named it)

~~Three small files~~.

Edit, I see that you have 4 part files, so that makes 5 files total.

These 5 files are the only files needed.

Re: Spinning top dynamic simulation

sbjs7608 — Mon, 10 Aug 2020 14:00:52 GMT

Are you asking me to upload like this?

https://a360.co/2XPl80O

https://a360.co/2XNRrNt

https://a360.co/3fDSx4A

https://a360.co/3koYZ2S

https://a360.co/2XNRt83

Re: Spinning top dynamic simulation

JDMather — Mon, 10 Aug 2020 15:27:17 GMT

Something is wrong with your *.iam file - it should be very small file size.

I am interested in figuring out what is wrong with it, but I will probably simply rebuild a new assembly from scratch.

You should have only a Spatial Joint.

The parts Device to apply weight, spinning top and spinning top low part should be a "Welded Group" as they all move together. Mate appropriate workplanes between these three parts.

Note that if I build a new assembly - it is less than 200KB

Re: Spinning top dynamic simulation

sbjs7608 — Mon, 10 Aug 2020 16:34:40 GMT

If I apply a weld group, are the displacements and angles relative to the x,y,z axes unconstrained to each other?

The lower part of the actual top is made like a spherical bearing.

That's why I chose Spherical for constraints.

I will upload a related similar picture to help you understand.

There is actually a bearing between 'Device to apply weight.ipt' and 'spinning top.ipt'.

Each 'ipt' is fixed by this bearing and only rotation is free

Without making 'bearing.ipt' , I wanted to simulate it by assembling it as if 'bearing.ipt' was between two 'ipt' using only constraints.

Also, I did not know what the bearing friction coefficient was, so i applied only the existing damping value of 1.

And the coefficient of friction between 'Device to apply weight.ipt' and 'spinning top.ipt' is set to 0.

I will upload a related picture to help you understand.

Finally, my personal opinion on the capacity is that the capacity is large because the position and speed through the simulation were tracked and saved.

Have you tried running the saved simulation?

If I just assembled without running the simulation, wouldn't the capacity be small?

Thank you

Re: Spinning top dynamic simulation

JDMather — Mon, 10 Aug 2020 16:56:53 GMT

I have a better idea of what you are trying to do.

But the assembly file should not be that large.

I have done hundreds of Dynamic Simulations with Traces and have never had a file size that large.

I do a similar problem in my class and sometimes the students go really crazy with this - I don't recall a file size this large. (Not even close, not in any analysis we have ever done.)

Re: Spinning top dynamic simulation

sbjs7608 — Mon, 10 Aug 2020 17:09:44 GMT

Did you see the text I just edited and the 3 photos? I am worried that you understand what I want. Because my English is not very good.

Re: Spinning top dynamic simulation

JDMather — Mon, 10 Aug 2020 17:12:39 GMT

Your English is fine.

I have a better understanding of what you are doing now.

Do this experiment - create a new assembly file and set this up again.

Does the file size in the new assembly get huge?

Re: Spinning top dynamic simulation

sbjs7608 — Mon, 10 Aug 2020 19:01:33 GMT

The assembly to be reloaded now has been simulated for about 3 seconds.
Assembly2 is not simulated.
Everything else is the same.
The first assembly with a large capacity was simulated in about 20 seconds.
Did you run the simulation I set up to the end?
It seems that there is a difference in capacity as much as the time the simulation was run.

https://a360.co/2DLiZMl
https://a360.co/3kAqAhU
https://a360.co/2XMd3tK
https://a360.co/3ak4HhV

assembly(simulated 3 second)
https://a360.co/3irAa4x 

assembly2(unsimulated 0 second)
https://a360.co/3kxPApW

By the way, is this the right way I'm going to do it?
Is the dynamic simulation I want possible?
If possible, and if this is the way I'm trying to do it, please let me know if there are any small parts that are wrong or if there is anything else to fix.

Re: Spinning top dynamic simulation

sbjs7608 — Wed, 12 Aug 2020 16:41:30 GMT

The assembly to be reloaded now has been simulated for about 3 seconds.
Assembly2 is not simulated.
Everything else is the same.

The first assembly with a large capacity was simulated in about 20 seconds.
Did you run the simulation I set up to the end?
It seems that there is a difference in capacity as much as the time the simulation was run.

https://a360.co/2DLiZMl
https://a360.co/3kAqAhU
https://a360.co/2XMd3tK
https://a360.co/3ak4HhV

assembly(simulated 3 second)
https://a360.co/3irAa4x

assembly2(unsimulated 0 second)
https://a360.co/3kxPApW

By the way, is this the right way I'm going to do it?
Is the dynamic simulation I want possible?
If possible, and if this is the way I'm trying to do it, please let me know if there are any small parts that are wrong or if there is anything else to fix.