PSI formula for pneumatic pistons

[Matt Adams]

Originally Posted by Ryan

Thanks, I need to clarify my question. If the PSI isn't on the piston, what formula do you use to figure it out? It's for a project in my robotics class.

If you would like to treat it as a "thin-walled pressure vessel" I could get you the formula for that... it is:

Max Tangential (hoop) Stress = p * (di + t) / (2t)

p = pressure inside the vessel
di = inner diameter
t = wall thickness

Max stress for steel varies widely.. from maybe 30,000 to 150,000 psi. Assuming you know this, you can re-arrange the above equation to solve for the max pressure inside. (then divide this by maybe 1.5 or 2 for a factor of safety, probably more since failure would be catastrophic!)

A longitudinal stress also exists because of the pressure on the end of the vessel.

this stress is equal to: (p*di) /(4*t)

If you want to think of these as pressurized cylinders that are NOT thin-walled, ie. the thickness of the wall is greater than 1/20th the radius, the formulas become more complicated.

Let me know what you need, I can come up with them pretty quick.

Matt