Anybody help with these questions?

[scw1]

Anybody help with these questions?

Homework Statement

A spherical pressure vessel has been designed such that the tensile stresses in its walls should not exceed 150MPa. The ratio of the vessels radius to wall thickness is 100. Applying a thin-walled plane stress assumption, what is the maximum uniform internal pressure that the vessel is intended to contain?

Homework Equations

Thin walled pressure cylinder assumption P= sigma(s) x radius/2xt(s)

The Attempt at a Solution

i tried the answer 0.15MPa but not sure if its right can anyone help me??

 

[rock.freak667]

Your equation should read σ= (Pr)/t or P = σt/r

 

[scw1]

Your equation should read σ= (Pr)/t or P = σt/r

Hi how do you denote the radius to wall thickness, is it 100 to 1 or 10 to 0.1?
Many thanks
Stevo

 

[rock.freak667]

Hi how do you denote the radius to wall thickness, is it 100 to 1 or 10 to 0.1?
Many thanks
Stevo

since r is the radius and t is the wall thickness

radius to wall ratio = 100 OR r/t = 100.

 

[nvn]

Good advice by rock.freak667, except the equation should be sigma = p*r/(2*t).

 

[rock.freak667]

Good advice by rock.freak667, except the equation should be sigma = p*r/(2*t).

Yes it should, I was thinking about a thin-walled cylinder.