Stiffness and strength of hierarchical polycrystalline materials with imperfect interfaces

►► Generalized expressions for the Voigt and Reuss estimates of the bounds to the effective elastic modulus of heterogeneous materials, considering imperfect interfaces. ► Effect of hierarchy of the material microstructure on stiffness, strength and anisotropy of hierarchical cellular polycrystalline materials. ► Numerical characterization of the interaction between interfaces at different hierarchical levels and determination of the condition for scale separation.