 # New function request

I wish Kiwi3D can output bending energy per unit area and membrane energy per unit area.

Probably it is possible to compute them from principal membrane stresses and principal bending moments but am not sure Maybe, if Poisson raito=0, then, they are like this membrane energy per unit area=1/E(N1N1+N2N2) (I think this is correct)
bending energy per unit area=??(M1M1+M2M2) (what’s the coefficient for bending energy?)

Hey,
if it is only about the distribution, i.e. per unit area, and not the total amount, you can already compute it with the existing version, see the file.
StressStrainEnergy.gh (29.4 KB)
The energy should be: Energy = 0.5 * (N1 * E1 + N2 * E2 + N12 * E12) where E1 = (N1 - nue * N2) / (E * t), E2 = (N2 - nue * N1) / (E * t) and E12 = N12 * 2 * (1 + nue) / (E * t). For the bending energy you have to divide by (t^3/12) instead of t.

Thanks Ana! Thanks for sharing the script. That’s helpful…

I would say I was close… I didn’t know there is a way to calculate strain from stress backward.

You only have to invert the material matrix. The formulas work only for linear elastic isotropic material and shells/membranes.

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