## Initial yield stress Vs. tensile strength

Are those the same? if not, how do I calculate the initial yield stress from the tensile strength? all the materials properties I see on the web only specify tensile strength, and I need the initial yield stress as an input on non-linear FEA analysis. Is it possible to extract the initial yield strength from a stress-strain curve?

Thanks.

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 Why do you think that the usually specified property is the tensile strength?
 Let me rephrase (made some mess with the terms): Usually I get the tensile stress at yield (or yield strength). I need the initial yield strength, are they the same? or is the initial yield the end of the elastic portion of the curve? Forgot to mention that I am dealing with plastics, so the linear portion is somewhat vague when I plot the results of a tensile test.

## Initial yield stress Vs. tensile strength

I suppose it's because plastics harden by deformation, so subsequent tests would obtain a higher yield.

 So, Is "initial yield strength" the same as "yield strength"? Currently I get good results when using the "yield strength" as the "initial yield strength" in the FEA software (Femap) so I guess its the same, but could someone please shed a light on the subject? Thanks.
 Do you not think you should study and understand the basic general load/extension graph of ductile materials before messing with FE analysis?
 I will be happy if you could give me some pointers instead of riddles... I will also be happy if you could explain how did you come to think that I don't understand/know the general concepts of the stress/strain curve. Please understand - I don't pretend that I do understand the concept fully these days (last time I studied it was 10 years ago) but I am not completely clueless, there is a language barrier and it may be that some terms are being confused when translated to English, but it seems to me that this is the reason such a forum exists, in my point of view it is OK that you are trying to make me do my home work before I ask a question, but not giving the answer and patronizing misses the point of such a forum.