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Abaqus: how to plot overall stress-strain curve?

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falloutranger

Materials
Aug 10, 2015
5
Hi all,

How to plot the overall stress strain curve for multiple elements? For example, I'd like to simulate the deformation of a material. The mesh consists of 1000 elements. When the calculation completes, I want to extract the overall stress-strain curve for the whole model (1000 elements). How do I do that?

So far I've seen two different approaches. One is to extract the stress and strain values in each element (for example LE33, S33 etc. in each element), then average the values over all 1000 elements. The averaged stress strain values are the overall stress strain for the whole model, which can be combined into a stress-strain curve. The other approach is to create a reference point, then constrain it with the surface on which the force is loaded via Equation Constraint in the Interaction Module. After the calculation, first extract the reaction force (RF33) and displacement (U3) of the reference point, then convert the displacement U3 into engineering strain by dividing it by the original length of the material, and convert the reaction force RF33 into engineering stress by dividing it by the original area of the surface. Finally, convert the engineering stress-strain curve into the true stress-strain curve. I tried both approaches, but the stress-strain curves given by the two approaches are (slightly) different. So which approach is the correct one?
 
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Hi,

If you are doing an non-linear analysis, dividing by original length will not be correct. I assume you have put NLGEOM on since you get logarithmic strain (LE).
 
Hi hansini,

Yes I was doing a non-linear analysis. So you mean I should plot the stress-strain curve from LE33 and S33 of each element, rather than from the force-displacement relation of the reference point?
 
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