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Given: A steel (shear yield stressty = 20 ksi) pressure vessel operates at a pressure of 300 psi. The radius and thickness of the pressure vessel are 40 in. and 0.50 in., respectively. Req'd: Based on the maximum shear stress theory (Tresca) what is the factor of safety for the pressure vessel? |
sH = pR/t = 24 ksi and sL = pR/2t = 12 ksi
The maximum and minimum principal stresses are therefore:
sI = sH = 24 ksi and sIII = out-of-plane stress = 0 ksi
The maximum shear stress is:
tmax = (24 ksi – 0)/2 = 12 ksi
Therefore, the factor of safety is:
F.S. = ty/tmax = (20 ksi)/(12 ksi) = 1.67
F.S. = 1.67
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