3.2.2.2. Fully Anisotropic Linear-Elastic Material Properties

The procedure to calculate fully anisotropic linear-elastic material properties is similar to the one used to compute orthotropic linear-elastic material properties. The primary difference is that the full stiffness matrix must be computed. Still, each load case yields one column of the stiffness matrix. In contrast with the orthotropic linear elastic computations, more integrated force results must be extracted. For instance, in the tensile tests, both the normal components of the forces on the boundary faces and the tangential components are extracted and used to compute entries in the stiffness matrix. For the anisotropic linear-elastic case, engineering constants are not determined. The entire stiffness matrix is the primary result for this material type.


Note:  Non-periodic boundary conditions cannot be used for anisotropic linear-elastic materials, as they will yield incorrect results. For example, all the tangential forces on the boundary would be zero by definition for the tensile test (in x). This would lead to , , and being zero, which is obviously incorrrect for an anisotropic material.