Motor Sizing for Wheel Endurance Testing

AI Thread Summary
In a wheel endurance testing application, the motor sizing is crucial for effectively rotating a drum while applying force to various wheel sizes. The torque calculation should consider the radius of the drum if the motor is mounted on it, but the wheel's radius if the motor is attached to the wheel. The force applied by the wheel can lead to significant torque values, necessitating careful consideration of frictional forces from both the bearings and the deformed wheel. A variable velocity connection, such as a pulley-belt system or a variable frequency drive, is recommended to accommodate different wheel diameters and specified angular velocities. Proper torque calculations and motor sizing are essential for accurate testing results.
SR71
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Motor sizing for wheel endurance testing
I am working with a wheel endurance testing application. I am trying to size a motor for the system. Basically, I have a drum which has to be rotated by the motor. I have different size wheels that I have to test. The motor is supposed to rotate the drum and then the wheel is pushed onto the drum with a force.

My question is when I want to find the torque (Fx perpendicular distance) do I use the radius of the drum or the radius of the wheel being tested? Currently, I am using the radius of the drum as the wheel is being pushed onto the drum but this gives me huge numbers as the wheel is pushing with 1000-2500 lbs of force.

Thank you in advance.

Link:
Wheel Endurance FBD.png
 
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If the motor is on the drum then use the drum radius. If it is on the wheel then use the wheel radius.

Torque will be different in both cases but so will be the angular velocity. In both cases, the power will always be the same.
 
SR71 said:
My question is when I want to find the torque (Fx perpendicular distance) do I use the radius of the drum or the radius of the wheel being tested? Currently, I am using the radius of the drum as the wheel is being pushed onto the drum but this gives me huge numbers as the wheel is pushing with 1000-2500 lbs of force.
How is the radius of the drum or wheel relevant for this? The force is aligned with the axles so it's got no leverage. Am I misunderstanding the drawing? Or are you obtaining the tangential component due to the friction?

Since the angular velocity is constant during the test (or so I think from the video), I would say to size the motor you just need it to have enough torque to overcome the friction from the bearings and the friction due to the deformed wheel rolling.
I guess the second one should be the greatest one but I don't know how to derive it yet.
 

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Welcome, @SR71 !

Due to the different diameters of wheels to be tested, I recommend to engineer a variable velocity connection between motor and drum.
It could be a variable pulley-belt system, or a VFD (variable frequency drive), for example.
I assume each test has one or several specified angular velocities for the wheel.
 
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