Structural material properties must be input as an isotropic, orthotropic, or anisotropic material.
If the material is isotropic:
Young's modulus (EX) must be input.
Poisson's ratio (PRXY or NUXY) defaults to 0.3. If a zero value is desired, input PRXY or NUXY with a zero or blank value. Poisson's ratio should not be
0.5 nor 
-1.0. The shear modulus (GXY) defaults to EX/(2(1+NUXY)). If GXY is input, it must match EX/(2 (1+NUXY)). The GXY value ensures consistency with the other two properties.
If the material is orthotropic:
EX, EY, EZ, (PRXY, PRYZ, PRXZ, or NUXY, NUYZ, NUXZ), GXY, GYZ, and GXZ must all be input if the element type uses the material property. There are no defaults. For example, if only EX and EY are input (with different values) to a plane stress element. The program generates an error message indicating that the material is orthotropic and that GXY and NUXY are also needed.
Poisson's ratio may be input in either major (PRXY, PRYZ, PRXZ) or minor (NUXY, NUYZ, NUXZ) form, but not both for a particular material. The major form is converted to the minor form during the solve operation (SOLVE). Solution output is in terms of the minor form, regardless of how the data was input. If zero values are desired, input the labels with a zero (or blank) value.
For axisymmetric analyses, the X, Y, and Z labels refer to the radial (R), axial (Z), and hoop (θ) directions, respectively. Orthotropic properties given in the R, Z, θ system should be input as follows: EX = ER, EY = EZ, and EZ = E θ. An additional transformation is required for Poisson's ratios. If the given R, Z, θ properties are column-normalized (see the Mechanical APDL Theory Reference), NUXY = NURZ, NUYZ = NUZ θ = (ET/EZ) *NU θZ, and NUXZ = NUR θ. If the given R, Z, θ properties are row-normalized, NUXY = (EZ/ER)*NURZ, NUYZ = (E θ/EZ)*NUZ θ = NU θZ, and NUXZ = (E θ/ER)*NUR θ.
For all other orthotropic material properties (including ALPX, ALPY, and ALPZ), the X, Y, and Z part of the label (as in KXX, KYY, and KZZ) refers to the direction (in the element coordinate system) in which that particular property acts. The Y and Z directions of the properties default to the X direction (for example, KYY and KZZ default to KXX) to reduce the amount of input required.
If the material is anisotropic: