# Frictional Heating of Ball on disc

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• Last Post 25 January 2020
ashishxh posted this 15 January 2020

Please I need help with this problems:

1. I couldn't rotate the disc uniformly. ( I want to rotate the disc at 2 rpm uniformly).

2. I want to calculate temperature of "Ball on disc" for "20 minutes time". I need help with "ANALYSIS SETTING".
( The disc doesn't rotate on increasing time).

3. How to give convection temperature in my problem?

ashishxh posted this 17 January 2020

Dear community members,

Regards,
Ashishkumar

peteroznewman posted this 19 January 2020

What is holding the ball so it is able to apply a force to the wheel? Whatever is holding the ball will affect the thermal solution of the ball.

What are the material properties of the ball and wheel?

What is the force that presses the ball against the wheel?

What is the coefficient of friction between the wheel and the ball?

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ashishxh posted this 19 January 2020

HI @Peteroznewman

I have attached the file in zip format. Can you please once check it?

I have given displacement to the ball, where i kept it fixed in "y and z direction" and free in x-direction. I applied 8 Newton force on a ball in x-direction, to apply force on a wheel. The disc rotates at 2 rpm.

The ball is "Tungsten Carbide" and Wheel is "Titanium".

The force that presses the ball against the wheel is 8N.

The coefficient of friction is 0.362 between the ball and wheel.

Thank you.

ashishxh posted this 19 January 2020

• The ball is made of "Tungsten carbide" and Wheel is "Titanium".
• The coefficient of friction between the ball and wheel is 0.362.
• The force that presses the ball against the wheel is 8 N.

• The wheel rotates at 2 RPM.

This is the setting i used for 0.3 seconds with remote displacement. There is 0.064 rise in temperature. I want to calculate it for 20 minutes. Please give me suggestion and where i went wrong?

peteroznewman posted this 19 January 2020

What is holding the ball so it is able to apply a force to the wheel? Whatever is holding the ball will affect the thermal solution of the ball.

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ashishxh posted this 19 January 2020

This is how my problem looks. Should i consider whole geometry?

• The ball is inside the casing "In figure bottom part".

There are attachments on the ball. But I didn't use it for simulation.

You mean, the attachments on the ball?

ashishxh posted this 19 January 2020

What is holding the ball so it is able to apply a force to the wheel? Whatever is holding the ball will affect the thermal solution of the ball.

I should give "Fixed support" to the ball? In that case, how can i apply force.
or
I should use joint-Body to Ground-Translational?

Please can you give me an idea. Thank you.

peteroznewman posted this 19 January 2020

Yes, you should include the cup that holds the ball and use a frictionless support on the cylindrical surface of the shaft of the ball holder.

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ashishxh posted this 20 January 2020

• Is this problem can't be solved only with ball and disc?

• I have solved it with ball and disc. But my problem was- I couldn't rotate it for long time. May be i have went wrong with analysis setting or something.

peteroznewman posted this 20 January 2020

Yes, you can simulate just a ball, but if you build a device and measure the temperature, the ball holder will take heat away from the ball, so the simulated temperature will have a large error from the measured temperature.

Do you have the disc rotating now?

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ashishxh posted this 20 January 2020

1.    Yes, it really makes sense to me. I will use the whole device.

2. I have done the previous problem with finite rotation of 30 degrees. It rotates. But i couldn't rotate it for large time step.
The possible reason is :

Can you suggest me, how can I improve my mesh?

It spherical body and disc. How can i mesh it?

Again i will end up with the same problem while doing with whole device.

Thank you so much for your time.

Regards,
Ashishkumar

peteroznewman posted this 20 January 2020
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ashishxh posted this 20 January 2020

HI,

I have solved it including the upper case. I am getting an error " Large deflection effects are active, which may have invalidated some of your results of force, displacement, frictionless support.

peteroznewman posted this 21 January 2020

That is not an error, it is a warning.

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ashishxh posted this 22 January 2020

I have solved it. Thank you so much for the help. My one last question is:

I want to simulate it for large time step. how to achieve that. Please help me with this.

Thank you.

peteroznewman posted this 25 January 2020

Just type in a larger end time for the simulation.

20 minutes = 1,200 seconds.