Learning Forum

[Kyle]

Hi guys!

I have a question is how do we adjust the result if the Force vs Time plot has a large oscillation in LS-DYNA? I am performing the high strain rate tensile testing in LS-DYNA.

Does anyone can please give me some suggestions about how to solve this issue?

Great Thanks!

Kyle

[Ram Gopisetti]

use some sort of filter (butterworth) and put some window frequency to smooth out but what do you mean by oscillations in the plot, any image for better support.
Cheers, Ram

[Kyle]

Thanks for your answer!!!
I can provide the figure plot to see how it goes! The JC model that I run corresponding to the tensile test with loading rate with respect to 950/s. The nodal force that I traced at one end and fixed another end.
This is the plot,

After I filter, I got this!

And then, why I doing force vs time plot, I want to get true stress and strain curve to the end since I cannot find a way to directly plot engineering stress/strain and true stress/strain. And there are only effective stress and effective plastic strain, which cannot be converted to the desired results.

[Ram Gopisetti]

you can use the cross plot option in LSPREPOST to plot the stress vs strain (v-m vs eps)these are true stress and strain and then use the reverse formula based on your specimen diameter and elongation to convert the plot to engineering strain and strain.
Check the following file as a reference for tensile testing .
you can also further smooth the graph.
cheers, Ram

[Kyle]

Thank you so much for your comments, !!! Will check these out!
Kyle