Correspondence Principle in Viscoelastic Functionally Graded Materials

This paper presents an extension of the correspondence principle (as applied to homogeneous viscoelastic solids) to nonhomogeneous viscoelastic solids under the assumption that the relaxation (or creep) moduli be separable functions in space and time. A few models for graded viscoelastic materials are presented and discussed. The revisited correspondence principle extends to specific instances of thermoviscoelasticity and fracture of functionally graded materials.