Question

Is the following statement true or false?

"Shear stress caused by a Torque is always in the direction of Torque.”

Answer 1

Torsion causes twisting of an object. In non-circular cross section, twisting is also accompanied by warping (distortion which causes transverse section to not being a plane anymore).

Now when a shaft is loaded only in torsion, then one of the principal stresses will be in tension and other in compression and they are oriented in such a way as to make a 45 degrees helical angle around the shaft. Mohr's circle is used to resolve the shear stress in the shaft into principal stresses.

Thus, the statement given is false. Hope you understood.