Stress-Strain Relation

I am modeling wind blades using PCOMPG entry in Nastran. I am using linear static solver (SOL 101). I request stress and strain outputs. However when I check the ply stresses and strains I have a problem with the stress strain relation. Normally Stress / Strain must give the Young’s Modulus (E). But when I divide the computed ply stresses by computed ply strains I don’t obtain E value of the material. The value I get is way different from E. Is this reasonable what might be the reason of that?


For isotropic materials, you have to take into account poisson’s ratio:

Strain-x * E = Fx - uFy - uFz

For orthotropic it get more complicated because you have Ex, Ey, and Ez. And we haven’t talked about shear. Look up Hooke’s law for orthotropic composites:…

Above is a snippet.