Stress Linearisation Question

[engtime]

Hello, I'm a recent Mechanical Engineering graduate and have recently began working with Abaqus. I am designing a pressure vessel (obviously in a junior role, trying to get to grips with the software etc). Now I am getting my head around the idea of stress linearisation (wasnt mentioned at uni) and splitting the stress into a membrane and a membrane + bending component. What I am not too sure about is the output generated by Abaqus (textfile). What is the difference between the "Component Results" and the "Invariant Results"? I have been advised to use the invariant results but wasnt given much of an explanation, and I could not find anything in the help file. Thanks for any help provided.

 

[TGS4]

This has been covered in significant detail in the Boiler & Pressure Vessel Engineering Forum. Take a look through the posts there. If you have any questions, that forum is probably a better location for your query.

A word of advice - your focus at this point in time should be the Code (ASME, PED, etc), and less about your FEA software.

 

[corus]

I thought Abaqus calculated this for you, but the stress linearisation will give you the equivalent linear bending stress through the thickness of the shell. The membrane stress is just the mean stress through the shell. This will remove any peak stresses so that the linear membrane and bending stress alone (hoop or axial) can be assessed against design limits (some proportion of yield). The membrane plus bending plus peak stress (or the total stress) would be assessed for fatigue damage.