Torque Lost to Torsion???

Sterlingz · 2016-02-22T08:34:38+00:00

So I'm a mining engineer working in a role where half of what I do is mechanical in nature. A discussion came up the other day where someone mentioned that torque is lost to torsion in a steel shaft, and I'm pretty sure that's false. Picture a steel shaft 400m in length and 500mm in diameter. When you apply torque on one end (with the other end secured), the shaft "twists".. Someone here is claiming you will lose torque to that torsion. IE: the torque on the other end will be lower because it's "lost" to torsion throughout. Can't seem to be right to me!?

Torque Lost to Torsion???

Sterlingz

Member

Updated: Oct 26, 2024

Views: 1.3K

So I'm a mining engineer working in a role where half of what I do is mechanical in nature.

A discussion came up the other day where someone mentioned that torque is lost to torsion in a steel shaft, and I'm pretty sure that's false.

Picture a steel shaft 400m in length and 500mm in diameter. When you apply torque on one end (with the other end secured), the shaft "twists"..

Someone here is claiming you will lose torque to that torsion.

IE: the torque on the other end will be lower because it's "lost" to torsion throughout.

Can't seem to be right to me!?

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Ramani Aswath

Member • Feb 22, 2016

That is exactly what happens with a spring. It is just a long wire with one end fixed and the other end twisted when the spring is extended. Within elastic limits no energy is lost. Once the applied torque is released the spring goes back to the unstressed state releasing all the energy.

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Sterlingz

Member • Feb 23, 2016

A.V.Ramani
That is exactly what happens with a spring. It is just a long wire with one end fixed and the other end twisted when the spring is extended. Within elastic limits no energy is lost. Once the applied torque is released the spring goes back to the unstressed state releasing all the energy.

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Right, so if you apply torque T on one end, there will always be an equal corresponding torque T on the other end?

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Ramani Aswath

Member • Feb 23, 2016

Sterlingz
Right, so if you apply torque T on one end, there will always be an equal corresponding torque T on the other end?
Under steady state, yes. However, if one end is fixed and a torque is applied at the other end, initially the shaft will see a gradually increasing twist. Depending on the stiffness after a time the torque will stabilize and the same torque will e felt at the fixed end.

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