Calculating to the torque required to rotate a drum

[motion123]

I'm looking for a procedure to calculate the torque required to rotate a horizontal drum filled with material.

 

[bigTomHanks]

I'll try to explain how to calculate the torque.

Imagine that you are looking at a circular cut-away of the cross-section of the drum. You will see a circle with the material resting on the bottom of the drum. The maximum amount of torque that will be required to rotate the drum will occur when the material in the drum is tilted to it's angle of repose. The angle of repose is dependent on the material and is defined as the angle with respect to the horizontal that can be observed if the material is poured into a conical pile. It is at this point that the material will stop "sticking" to the drum and will begin to slide down. This angle will be the angle of rotation that you will calculate the torque at. You will need to calculate the center of gravity of the material at this rotation and you will have where your moment arm is. You'll also need to add a little to account for friction.

I would do the calculation for you, but I don't have any resources here and I don't feel like spending the time to integrate to get the center of gravity.

Good luck,
bigTomHanks

 

[Pressed]

Ultimately you are looking for this, but there are others:

torque = moment_of_inertia * angular_acceleration
--------------------------------------------------------
To save yourself trouble, think about considering the cylinder a solid mass.

These links say the same thing but in different ways, and there is a lot of fluff in there as well.

http://www.vectorsite.net/tpecp_03.html

http://acad.udallas.edu/physics/GP1/rotational_motion_ii_faqs.htm

http://www.phy.cmich.edu/people/andy/Physics110/Book/Chapters/Chapter7.htm

http://www.cod.edu/people/faculty/wolfson/PHY151/Chapter9.pdf

http://www.physics.orst.edu/~rubin/COURSES/PH211/HW/answer8.pdf

http://www.batesville.k12.in.us/physics/PhyNet/Mechanics/RotMechanics/fall_slide_roll.htm

Just for fun

http://dept.physics.upenn.edu/courses/gladney/mathphys/java/sect4/subsubsection4_1_4_1.html

------------------------------------------
Another way is to attach a sensor and measure it in real time. Good luck.

_______________________________________
Feeling frisky.........

http://www.tailofthedragon.com