The viscoelastic behavior of a chopped glass fiber/polyester sheet molding compound (SMC-25) and of a modified epoxy adhesive (Metlbond 1113-2) as determined by creep and creep recovery tests is presented. A nonlinear viscoelastic characterization method of Schapery is presented and applied to the data for both materials. The nonlinear constitutive equation so obtained is used together with a delayed failure law postulated by Crochet to describe creep rupture data for both materials. Discussion is also given on the feasibility of applying the nonlinear viscoelastic procedures of Schapery in conjunction with the time-temperature superposition principle to obtain a time-stress-temperature surface to define failure. / Master of Science