Anisotropic Stiffness Tensor
Defines an Anisotropic Linear Elastic Property by specifying a positive definite, second order, symmetric stiffness tensor in Voigt notation for the constitutive relationship sigma_i = C_ij * epsilon_j (i,j=1,6), where sigma = (sigma_xx, sigma_yy, sigma_zz, sigma_yz, sigma_zx, sigma_xy) and epsilon = (epsilon_xx, epsilon_yy, epsilon_zz, gamma_yz, gamma_zx, gamma_xy). Providing scalar fields as inputs will result in spatially varying material properties.