0
$\begingroup$

Should standard SI units be used in this formula or are other units supposed to be used for the formula for stress in a thin-walled spherical pressure vessel?

$$\sigma_{yield}=\frac{P_g r_i}{2t}$$

where $\sigma_{yield}$ is the yield strength of the material, $P_g$ is the gauge pressure, $r_i$ is the inner radius of the sphere, and $t$ is the thickness of the sphere wall.

$\endgroup$

2 Answers 2

7
$\begingroup$

You can use any consistent set of units. That includes SI.

But if you try to use a pressure in ATM, a sphere radius in feet, a wall thickness in mils, and want the stress in tons per square inch, you will probably get the wrong answer that you deserve!

$\endgroup$
1
  • $\begingroup$ Unless you use the disgusting conversion factor that would go along with it! $\endgroup$
    – JMac
    Commented Jan 18, 2017 at 17:33
-2
$\begingroup$

Yield should be in MPa, Pressure Pa, and R in mm t is thickness therefor mm

$\endgroup$
1
  • $\begingroup$ Any justification or sources for why those units must be used? I'm quite confident that just because t is thickness it doesn't need to be mm. $\endgroup$
    – JMac
    Commented Jan 19, 2017 at 11:55

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.