Pressure vessel - Von Mises Stress
Pressure vessel - Von Mises Stress
(OP)
I've got a small cylinder of 3 in. OD, 2. in ID running a pressure of 2000 psi. I am familiar with hoop and longitudinal stress calculations. How do I calculate the von Mises stress?





RE: Pressure vessel - Von Mises Stress
Now, for a tough question, why are you needing to calculate the von mises stress? What will you do with this scalar?
RE: Pressure vessel - Von Mises Stress
Sigma 1 = PR/t
Sigma 2 = PR/2t
And sigma 3 = 0
Using the von mises approach to calculate an effective stress under the given conditions;
Sigma e = von mises equation
Plug in the values for the principal stresses and calculate sigma e
If sigma e is less than the tensile yield strength, no permanent deformation will occur.
RE: Pressure vessel - Von Mises Stress
To answer your question (with no regard to "why") go to B31.3 and look at Chapter IX. Go to paragraph K304.1.2 (note the "K" paragraph) and read the paragraph and especially the notes.
For some background on failure theories you might find this interesting:
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Regards, John.
RE: Pressure vessel - Von Mises Stress
To answer your question directly, a pressure vessel 3.0 OD X 2.0 ID holding 2000 psig would have a maximum stress of 6235.38 psi on it.
Taking into account significant digits, I would report 6200 psi as Von Mises-Hencky stress.
Kenneth J Hueston, PEng
Principal
Sturni-Hueston Engineering Inc
Edmonton, Alberta Canada