Optimum linear and nonlinear viscoelastic designer functionally graded materials-Characterizations and analysis

A pilot study of the elastic and viscoelastic behavior of functionally graded materials (FGMs) is presented by considering them solely and primarily as having prescribed nonhomogenous mechanical properties, such as relaxation moduli and/or failure envelopes. Such an umbrella FGM definition, of course, includes composites. The consequences of FGM prescriptions on solution patterns are examined in detail. Protocols are formulated for the analytic determination of material properties tailored to specific service conditions. The inherent difficulties associated with such inverse approaches used to generate expressions for designer FGMs are discussed.