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PTB-3 - E5.2.3 - Stress strain curve data

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pvros

Mechanical
Nov 16, 2023
15
Dear All,
I am replicating the example problem E5.2.2 and I am facing some issue in the inputs.
I have created my own spreadsheet as per annex 3D and I am comparing my results with the material input data given at E5.2.3.

Why as per E5.2.3 in the tab data elastic strain is considered equal to zero?
Are the strain data in the PTB3 tab only plastic strain and in the actual curve considered by the software the plastic strain data are summed to the "nominal" elastic strain (sy/Ey)?

Moreover, how are calculated the strain data in the tab? Should i subtract to the total strain values as per annex 3D the elastic strain at yield value calculated as per annex 3D?
Even if I "clean" the total strain I have calculated with the calculated elastic strain at yield as per annex 3D I obtain always a discrepancy of 0.5-2% between my strain values and ptb-3 strains.

What am I missing?

Thanks!






 
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Do you know the difference between Elastic strain and Plastic Strain?
 
I think so, but i do not get your point.
It is just my wording not totally correct (i have tried to edit the original post and make it more clear) or i did a trivial mistake?
 
I think that the strain numbers in PTB-3 are Plastic strain because at Yield you would expect plastic strain to be zero...ish. I think that Appendix 3D material curve is outdated. The current Appendix 3D produces a small amount of Plastic strain below the yield stress.
In ANSYS, the user inputs only, Elastic modulus and a table of True Stress vs True 'plastic' strain to produce the Elastic-plastic stress strain curve. Perhaps it is the same for Abaqus.

From Appendix 3D, True Plastic Strain = True Total Strain - E/σ[sub]True[/sub]
 
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