For isotropic material an elastic modulus, like Young's modulus and in combination with a Poisson ratio can be used to convert to any other elastic modulus, like for example the bulk modulus. Tables for these conversions exist, for example, on the wiki page of bulk modulus.
I'd like to use the conversions for FEM material models that are plane strain, plane stress or axisymmetric. What confuses me on the wiki page is that there is a mention of 3D material and 2D materials and these have different conversion formulae. It's unclear to me what 2D material means in this context. My questions:
Is it correct to use the 3D material conversion formulae for the plane stress case? My current thinking is that the conversions are valid for the plane strain and axisymmetric case as they model objects with 3D extend. But the plane stress case a models a thin object. Which formula should be used in that case?
Can anyone share a reference to where these conversions are derived, possibly including the 2D material conversions.