Viscoelastic equilibrium problems of KIRCHHOFF plates can be solved in a closed form only under special geometric assumptions, loading conditions and kinematic constraints on the boundary. A new solution procedure, based on a correspondence principle between a linearly elastic, homogeneous and orthotropic SAINT-VENANT beam under torsion and an isotropic linearly viscoelastic and functionally graded KIRCHHOFF plate with no kinematic constraints on the boundary, is proposed. The methodology is adopted to eval- uate displacement, bending–twisting curvature and moment fields of an elliptic plate, with viscoelastic constitutive behavior and loading conditions described by convolution integrals, assessing thus new benchmarks for computational mec...