Autodesk Inventor

[#1]

Hi

as part of a college project im trying to analyse a stress analysis on a closed cylinder on inventor.

ive drawn the cylinder and done the stress analysis but the results are confusing me (allot) maybe its just my inexperience..

In an experiment i pressurised the cylinders till fail and they fractured at 610 bar. but in the analysis the max stress is turning out oto be  555 mpa. on the von misses stress.  this is way above what i expected  and wondered if anyone could advise me on what i might be doing wrong?

ive attached the cylinder in question..

Thank you Kindly

[#2]

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eugene.byrne wrote:

In an experiment i pressurised the cylinders till fail and they fractured at 610 bar. but in the analysis the max stress is turning out oto be  555 mpa. on the von misses stress.  this is way above what i expected  ...

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The yield strength for your material selection is 350MPa.  Yield strength is not the same as fracture point.

It doesn't sound like you are using FEA analysis correctly in relation to your expectations from the physical experiment test.

What textbook are you using?

The use of the FEA analysis is the linear portion of the stress/strain graph below yield strength, in the elastic area of the graph - not a measure of fracture point.  In other words, if the pressure is removed the part returns to it's original dimensions. (Safety Factor greater than or equal to 1.)

[#3]

I nearly forgot to mention - the process of manufacturing that pressure vessel sends the material well into the plastic deformation portion of the curve.

Some other software might be more appropriate for this analysis.
I don't know enough about Autodesk Analysis (formerly Algor), but might be worth a check to see what pressure vessel analysis tools it has.

Students can download Autodesk Analysis for free from http://www.autodesk.com/edcommunity