# Differing values for Modulus of Resilience

Hi, a newbie here.
I have a problem, using the 2 different equations for calculating the Modulus of Resilience, I get 2 different answers. It seems simple, but I’m a little perplexed.
For the following values:

• Yield Stress = 1880 MPa
• Yield Strain = 0.0068
• E = 401 GPa
[U(r) = (Yield Stress x Yield Strain) / 2] - answer = 6.39 MJ/m^3
[U(r) = Yield Stress^2 / (2 x E)] - answer = 4.4 MJ/m^3

Sorry if this is the wrong forum.
Thanks

You’ll probably want to change to the ScienceTalk category, as I don’t think this has anything to do with Ovito…

As for your question, they differ because the modulus E isn’t defined by the yield stress and strain, but by a linear fit during linear deformation. If you defined E = Yield Stress / Yield Strain, then the two equations would be equal, but the line representing Stress = E * Strain would be a poor fit.

Hi Michael, yes, that makes perfect sense. I will just leave it at that as I’m unsure how to move/transfer the comment, if that’s ok.