Plastic strain requirement in Section III

[Raidrp]

Hello guys,

I would like to know what if there is any percentage limit on the plastic strain in a plastic analysis ( limit load or elastic plastic). I know there is for plastic collapse (2/3 of design pressure).
If not, what is acceptable limit.

Thank you

 

[r6155]

1) Nuclear is a serious issue. Experience is required in design, fabrication and inspection.
2) Contact a pressure vessel engineer.

Regards

 

[TGS4]

While I echo r6155's sentiments, I will add a few technical responses.

The magnitude of the plastic strains in a Limit Load analysis are non-physical, and therefore should not be relied upon for any purpose whatsoever.

An elastic-plastic stress analysis used the concept of LRFD (Load and Resistance Factored Design). Therefore, although the strains should be physical(assuming that they are based on a reasonable stress-strain curve), in general you are using a factored-load approach. Therefore, the only strains that would have any physical relation to reality would be those at the design-level loads (unfactored). Beyond that, the criteria of the EP method (note that this is a method for determining Protection Against Plastic Collapse - yes I realize that I am using VIII-2 terminology, but the same concept applies to Section III) is based on lack of convergence of the numerical model, and note on a plastic strain limit.

Do you have a specific question about a specific paragraph? Perhaps we can assist you with additional specificity.