I am trying to figure out how much torque this piece of metal that I have can deal with before breaking.

Are there any tools online that can help me calculate these items?

The hardness of this iron is 167-229Ha tensile strength is >=58kg/mm2 elasticity is >= 45% density is 0.785

Currently the pipe is a hexagaon that's 55mm in diameter, then the ends are cylinders that are 40mm in diameter.

Since this is early in the design phase I'd like to be able to adjust torque and the size of the metal pipe so that it wouldn't break.

Currently I have 1200RPM 15HP motor that I have reduced down to 85RPM which if I calculated correctly should be around 926 ft-lbs of torque.

Are there any tools that will help me convert from ft-lbs to lbs-ft3 or calculate these values? one such online calculator.

  • $\begingroup$ Where do you get ft-lbs3 ?? $\endgroup$
    – Solar Mike
    Aug 18 '17 at 10:12
  • $\begingroup$ I was looking at some online calculators although I think it was lbs-ft3. I'll edit that. $\endgroup$ Aug 18 '17 at 10:25
  • $\begingroup$ ft-lbs is a torque ie force * distance same as Nm Newton metres is. $\endgroup$
    – Solar Mike
    Aug 18 '17 at 10:37
  • 1
    $\begingroup$ For tensile strength, kg/mm^2 does not make sense. This is typically expressed in Pa, i.e. N/m^2. Did you maybe start with a strength in lbf/in^2 and then convert pounds to kg? If so, you should have converted pounds to Newtons, as this is a force not a mass. $\endgroup$
    – Daniel K
    Aug 18 '17 at 12:16
  • $\begingroup$ odd as that unit is its not at all unusual come across such in published data. $\endgroup$
    – agentp
    Aug 18 '17 at 20:53

This page and this page would be good places to get you started.

In addition to my comment above, you'll probably want to design to the yield strength and not the ultimate tensile strength.

  • $\begingroup$ This is exactly what I was looking for. Thank you very much! $\endgroup$ Aug 18 '17 at 13:07
  • 1
    $\begingroup$ a link only answer can suffer from link "rot" - please quote the relevant material in the body of your answer for the future. $\endgroup$
    – Solar Mike
    Aug 18 '17 at 14:26

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