Compressive failure

  • Thread starter darkelf
  • Start date
  • #1
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Hello,

Does anyone know how to calculate the cross sectional compressive strength of a piece of pipe? I know as you compress or crush the pipe along the cross section of the pipe it will strain harden at which point compression will be unable to continue experimentally. I need to know what force would be required to overcome this and completely crush or compress the pipe on its sides.

I'm thinking of a hollow steel pipe with a wall thickness of say 3 1/2".

Thanks so much.
 

Answers and Replies

  • #2
dav2008
Gold Member
609
1
Note: I am assuming that by "along the cross-section" you mean you are loading the pipe like this: --> ===== <--

How long is your pipe segment? As your pipe gets to be a lot longer than it is wide then you have to consider buckling as a mode of failure. At that point, once it buckles it's pretty meaningless to ask what happens next since you've basically bent the pipe and are no longer loading it uniformly.

If the pipe is short then why do you say compression will be unable to continue experimentally? At some point it will plastically yield and begin to barrel out but you would still be able to load it as high as your tester will go.

You can predict the buckling load using buckling equations, and you can predict the yield point just by considering uniform compressive loading, but once it's yielded you need to define what you mean by "completely crush" the pipe. In theory you could continue crushing it until the pipe has turned into a pancake.
 
  • #3
77
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Thank you Dav2008,

At present, I am attempting to load the pipe like this ->||<-

The pipe length as such does not really play much a part but the length should be at least a feet long. I am trying to overcome the buckling that occurs on the side of the pipe as it is compressed as these areas experience increased strength due to strain strengthening or work hardening.

I am looking for an equation that can be used to calculate the load needed to completely crush the pipe.

Thank you.
 
  • #4
26
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darkelf you can use the usual equations for elasticity but in cilindrical coordinates (polar). You have a stress of sigma sub r with sigma sub theta =0 and sigma sub z=0. Then you can solve the system to obtain the deformation
 

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