Incremental Variational Principles and homogenization of nonlinear dissipative composites and polycrystals
Résumé
This study is devoted to the overall response of nonlinear composites or polycrystals comprised of phases which have a partly reversible and partly irreversible behavior. Upon use of an implicit time-discretization scheme, the evolution equations describing the constitutive behavior of the phases are reduced to the minimization of an incremental energy function. This minimization problem is rigorously equivalent to a nonlinear thermoelastic problem with a nonuniform transformation field Different techniques can be used for approximating the nonuniform eigenstrains by piecewise uniform eigenstrains and for linearizing the nonlinear thermoelastic problem. Applications to the transient response of two-phase composites under complex loading paths and to creep of elasto-viscoplastic polycrystals will be presented.