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Need help on a torque calculation.

  1. Jun 23, 2011 #1
    Good folks, I need some guidance.

    I have a shaft in a machine, hardened A2 tool steel- Rc 48-52 that is 2.126" dia., 3" long.

    This shaft will see a maximum peak torque loading of 2,500 ft/lbs.

    I am hopelessly mired in calculations I do not trust. Can someone weigh in? Is this shaft section satisfactory?

  2. jcsd
  3. Jun 23, 2011 #2
    Try this approach:

    Torque = J * allowable stress / radius

    J = polar moment of inertia = 1/2 * PI * radius^4

    allowable shear stress for tool steel - you will need to look up, but probably somewhere between 12 ksi to 20 ksi. If your tool steel is HRC, the yield may be much higher. See if you have MTR for the steel.
    Last edited: Jun 23, 2011
  4. Jun 27, 2011 #3
    Hi I'm new here. i just came across this post.

    edgepflow,no offence but won't that method account for only static loading?
    You might have to go through the whole shaft design process (Free Body Force diagrams-->BM and shear force diagrams-->stress calculation using endurance limit etc.) for fatigue loading(cyclic stress) since it will be mounted in a machine. I'd refer to Shigley's Mechanical Engineering Design book ISBN: 0−390−76487−6. To be honest i experienced MANY problems myself, when i designed my first shaft alone, so i know how it feels.
  5. Jun 29, 2011 #4
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