## Determining Inflection Point

## Determining Inflection Point

(OP)

I am calculating the stress-strain curve for a material and I want to find when the curve is no longer linear - aka when it enters the plastic region. I have the function for the curve and I would like to know how to find that point when the slope is no longer constant. I can take the first and second derivative and visually see the slope and change in slope but I do not know how to find the value where it changes.

Does anyone have any recommendations?

Thanks

Does anyone have any recommendations?

Thanks

## RE: Determining Inflection Point

TTFN

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## RE: Determining Inflection Point

What I would like to know is how do I calculate the point of deviation - is there a function in mathcad that does it for me or something similar? Is there a mathematical method that I can use the first or second derivative function and find the point that has a reasonable deviation?

Another question in itself is how do you determine what a reasonable deviation is - it is, for the example of the second derivative, where "y" is equal to 0.001?

Thanks

## RE: Determining Inflection Point

## RE: Determining Inflection Point

Peter Nachtwey

Delta Computer Systems

http://www.deltamotion.com

## RE: Determining Inflection Point

TTFN

FAQ731-376: Eng-Tips.com Forum Policies

Need help writing a question or understanding a reply? forum1529: Translation Assistance for Engineers

Of course I can. I can do anything. I can do absolutely anything. I'm an expert!

There is a homework forum hosted by engineering.com: http://www.engineering.com/AskForum/aff/32.aspx