Array nThe top matrix you show is the Anisotropic Elasticity material definition. That stiffness matrix is multiplied by the strains to get the stresses.n help page above says that you can define the material using the flexibility form (compliance) instead of stiffness.nInitialize the constant table (TB,ANEL or TB,ELAS,,,,AELS/AELF). Select the stiffness or flexibility form via the appropriate TBOPT value.nThe bottom matrix you show is the Compliance (flexibility) matrix that is multiplied by the stresses to get the strains and the values you show are for an orthotropic material. nAnsys can define an orthotropic material by providing the nine material constants.n can also use Engineering Data to enter Orthotropic elasticity.nNow you have to enter the 18 constants.nAlso in ANSYS HELP says that the matrix can be either rigid or pliable.nThe words I found in the Help system are stiffness or flexibilitynAn isotropic material is defined by only two material constants and an equation to get the third. The values to use in the anisotropic material definition using the Stiffness form is given by equation 6.3.21 in this reference: nhttp:/