Asymptotic analysis of heterogeneous micromorphic elastic solids
Résumé
Heterogeneous materials like metal polycrystals and metal matrix composites exhibit a size-dependent mechanical elastoplastic and fracture behavior. Generalized continuum theories can be used for the constitutive behavior of each constituent in order to predict such size effects. Extended homogenization methods are then needed to compute the effective properties of composite higher-order materials. Higher-order continua include the Cosserat medium for which the material point is endowed with independent translational and rotation degrees of freedom and the micromorphic continuum which accounts for the full microdeformation of a triad of directors attached to the material point. An asymptotic multiscale expansion method is used here to derive the effective properties of heterogeneous linear elastic micromorphic media. The type of continuum theory representing the effective medium is shown to be either a Cauchy, Cosserat, microstrain, or full micromorphic model, depending