Determining step time at first yield 1

[isok89]

Hi,


I'm conducting three point bending, displacement controlled. I would like
to calculate the yield moment by determining at what step time the first element yields. Does anyone know how I can achieve this?

 

[Dave442]

Can you not just flick through each frame in Viewer and see when your peak stress of interest first exceeds yield?

 

[Mustaine3]

It is easier to look when PE or PEEQ or ACYIELD become unequal zero.

 

[Dave442]

much better idea

 

[isok89]

I have to conduct 500-600 experiments with varyingg parameters.
I have a script currently, I would just like to implement this into my script.

But where do I find in the history or field data the ACYIELD or PE or PEEQ data for the entire model (is this even possible?). Whenever I plot this, I get the plots from all the elements.

I'm hoping to create a plot with step time on x-axis, and on y-axis ACYIELD, PE or PEEQ for the entire model.

 

[Mustaine3]

You can only create xy-data for every integration point, when your model is quite small.

I see two realistic options:
1. Use *El Print to write PEEQ into the .dat for every integration point in every frame. Then you can use a script to check if the maximum value (see Summary option) is larger than zero.

2. In the Scripting Users Manual is in Section 9.10.1 an example script, that looks for the Mises stress in each element in each frame. With few modifcations it can be used for your task.

 

[Mustaine3]

I think I have the solution for the problem. When plasticity occurs, it will contribute to the model energy. So you just have to look when history output ALLPD becomes nonzero.

 

[isok89]

thanks Mustaine3, your solution will save me a lot of time

I started writing a script which would check my maximum von mises stresses (=yielding stress for yield moment) after each analysis and would automatically reduce the prescribed plate displacement in increments until the max von mises stresses = yield stress of my material. But that would lead to countless iterations and a lot of computational effort.