What is Torsion?
Channel: MechanicaLEi
Date: 2018-06-20

Welcome back MechanicalEI, did you know that Torsion is what makes your car move and keeps your head from turning 360 degrees? This makes us wonder, what is Torsion? Before we jump in check out the previous part of this series to learn about How Shear Stress is distributed? 
Now, torsion is the twisting of an object due to an applied torque. It is expressed in newtons per square metre (Pa) or pounds per square inch (psi). For shafts of uniform cross-section, the torsion T is given by the product of torsion constant J t and Maximum shear stress tau divided by the distance between rotational axis and outer surface r. The maximum shear stress value for a solid shaft of diameter d with torque T applied to it, is given by T max equals 16T upon pi d cubed. The same value for a hollow shaft of outer diameter D not and inner diameter D i is given by tau max equals 1.066 into 16T upon pi D O cubed. Form the above equations we can infer that MAXIMUM SHEAR Stress is directly proportional to the torque applied and inversely proportional to the outer diameter cubed. The power transmitted by a shaft is given by the product of 2 pi N t upon 60 into 10 to the power 3. Where N is the speed in rpm. Theta here is the angle of twist. If two or more shafts of different material, diameter or basic forms are connected together in such a way that each carries the same torque, then the shafts are said to be connected in series & the composite shaft so produced is therefore termed as series – connected. Here in this case the equilibrium of the shaft requires that the torque ‘T' to be the same throughout both the parts and is given by G J theta upon L for each shaft. If two or more shafts are rigidly fixed together such that the applied torque is shared between them then the composite shaft so formed is said to be connected in parallel. For parallel connection. Total Torque T = T1 + T2 and the angle of twist for each portion are equal and can be obtained from t1 L1 upon g1 J1 equals t2 l2 upon g2 j2. Where G and J are Shear modulus and Polar moment of inertia respectively. Hence, we first saw what Torsion is, then saw how stresses occur in hollow and solid shafts and finally saw how shafts are connected in series and parallel?
In the next episode of MechanicalEI find out what Strain Energy is?

Attributions:

Doh De Oh by Kevin MacLeod is licensed under a Creative Commons Attribution licence (https://creativecommons.org/licenses/by/4.0/)
Source: http://incompetech.com/music/royalty-free/index.html?isrc=USUAN1100255
Artist: http://incompetech.com/

Subtle Library by Fabian Measures (http://freemusicarchive.org/music/Fabian_Measures/) is licensed under a Creative Commons Attribution licence ( https://creativecommons.org/licenses/by/4.0/)
Source: http://freemusicarchive.org/music/Fabian_Measures/Emotion_Music/Subtle_Library

https://en.wikipedia.org/wiki/File:Twisted_bar.png
By Orion 8 [CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0) or GFDL (http://www.gnu.org/copyleft/fdl.html)], from Wikimedia Commons