Results 1 to 4 of 4

Thread: Calculate Max Permissible Torque in a Shaft

  1. #1
    Associate Engineer
    Join Date
    Nov 2013
    Posts
    1

    Calculate Max Permissible Torque in a Shaft

    Any help with this would be much appreciated.

    I have a metal shaft - steel - it is of a certain diameter. How can I work out the max permissible torque for this geometry and diameter before the shaft fails?

    many thanks for anyone who can help.

  2. #2
    Administrator Kelly Bramble's Avatar
    Join Date
    Feb 2011
    Location
    Bold Springs, GA
    Posts
    2,400
    Welcome to EE!

    First, you need to determine the material characteristics (Young's modulus, Poissons ration and Modulus of rigidity).

    Next, determine the appropriate applied load with a FOS (Factor of Safety) - as you don't want to load the bar at yield or even close to yield.

    Then, see or use one the following calculators or videos..

    Shaft Stress and Deflection under Torque

    Torsion Formula - Mechanics of Materials

    Shaft Shear Stress due to Torsion

  3. #3
    Lead Engineer
    Join Date
    Aug 2013
    Location
    Houston TX USA
    Posts
    421
    With respect to the above please note that:

    1. When used for a rotating shaft the determination of the Factor of Safety or maximum allowable shaft must include a factoring for fatigue stresses due to varying shaft loadings and start/stop loadings if applicable.

    2. The above equations only apply to shafts in pure torsion with no applied bending forces from mounted gears, pulleys or sprockets for which the bending stresses and their inherent shaft bending fatigue stress must be included as a part of the shaft stress calculatiions and the selection of an acceptable maximum allowable stress for the shaft material.

  4. #4
    Administrator Kelly Bramble's Avatar
    Join Date
    Feb 2011
    Location
    Bold Springs, GA
    Posts
    2,400

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •