ABSTRACT
In classical linear elasticity, it is advantageous to use eigenspace projectors to describe the elasticity tensor. A similar approach can be applied at directed surfaces, whereby we reduce our concern to coplanarity of all material points of the surface. The starting point is the introduction of stiffness measures presenting the in-plane, the out-of-plane, and the transverse shear states at the surface. We assume these states to be uncoupled, but superposed eventually. For the special case of homogeneous surfaces composed of linear elastic and isotropic material, projection operators and eigenvalues of the stiffness tensors are exploited. Correlations to classical engineering parameters are identified and discussed. The entire procedure allows for a clear distinction of dilatoric and deviatoric portions of the constitutive equations.
