Those paper thin soda cans can hold soda at up to 50 psi at times,
as a more familiar example, of course.
Actually, attaching a strain gage to a full can and opening to check
the internal pressure by reading the delta strain is a popular
undergrad exercise, I understand.
jobijoba thought carefully and wrote on 11/21/2004 6:16 AM:
I don't know if you're naive, but there are two entirely different ways
to design pressure vessels (like railroad tank cars) depending on if
they are subjected to internal or external pressure.
The primary consideration for internal pressure design is to prevent
stresses from exceeding the strength of the material. An exploding tank
car is an example of stresses exceeding material strength.
The primary consideration for external pressure design is to prevent
buckling. I don't know too much about buckling, but I know it's more
complicated design process and difficult to predict. Your steam-cleaned
tank car is an example of buckling.
Here's a site that shows some typical equations for internal and
external pressure vessel design. Depending on which code you based your
design, the equations may be slightly different:
In addition to these equations, we also consider secondary effects like
welding, corrosion, material weight, local stresses created by
penetrations, dynamic forces, etc.
BTW, someone on your site mentioned that the tank car would probably
shrink perfectly in zero gravity.
That's not true, the car would buckle in much the same way.
Years ago at an unnamed nuclear power station, a large filament wound water
storage tank was hydro tested by filling it with water from a fabric fire
hose through a top-mounted connection and by then pressurizing it. At the
completion of the test, the tank was emptied through the bottom drain. The
crew had failed to disconnect the fill hose or otherwise vent the tank, the
hose sucked flat, and the tank imploded in impressive fashion.
Just because something isn't in the procedure doesn't mean you don't have to