Determine the largest allowable square cross section of a steel shaft of length 6 m if the maximum shearing stress is not to exceed 135 MPa when the shaft is twisted through one complete revolution. Use G = 77.2 GPa.© BrainMass Inc. brainmass.com October 9, 2019, 8:43 pm ad1c9bdddf
Consider the square shaft 6 metres long with each side being B cms.
The formula or shear stress due to torsion is
= T r / J (1)
where is the shear stress
T is the torque applied in Kg / cm2
. r is distance of the extreme point on the square shaft from the center of the shaft
J is the moment of inertia of the shaft
As the shaft is square in cross section the moment of inertia is
J = 1/12 ...
Word doc attached gives calculations to find the largest allowable cross section of a described steel shaft in revolution.