Single Cycle Pressure Test for Pressure Vessel

[Jschrodes4]

Homework Statement

I need to design a pressure test that, in one cycle, will simulate the 8000 cycles that a given pressure vessel will undergo. I know the dimensions and material of the vessel, the number of pressure cycles it will undergo, and the max and min working pressures.

Homework Equations

I found a variety of different equations, but they generally look like this: Testing Pressure = 1.5 x Max Allowable Working Pressure. However, none of these equations take into consideration the high number of cycles the vessel will have to undergo so I don't think they will work.

The Attempt at a Solution

I have not yet attempted a full solution as I am not sure if the equations I've found are applicable to what I need to do.

 

[jrmichler]

Since your profile indicates that you are currently an undergrad, this is apparently a homework problem. I would refer you to the ASME Boiler and Pressure Vessel Code, but that runs to some 16,000 pages. You are correct in that what you have found so far does not take into account cyclic loading.

You have a metal fatigue analysis problem, and a basic introduction to metal fatigue takes a full semester senior level course. You can test the static strength by a single cycle overpressure test, but not the fatigue strength. A good read is the accident report for the De Havilland Comet airliner. Here's one link: https://web.archive.org/web/20091026195856/http://geocities.com/CapeCanaveral/Lab/8803/fcogalyp.htm. Note especially how and why a few overpressure tests caused the initial fatigue test fuselage to last much longer.