The thermoelastic response of cracked polycrystals with hexagonal symmetry
Résumé
The influence of a population of randomly-oriented cracks on the macroscopic thermal and linear-elastic response of a hexagonal polycrystal is addressed using a self-consistent method. Coupling between micro-cracks and crystal anisotropy is taken into account through the effective medium where all inhomogeneities are embedded. In the absence of cracks, the proposed approach reduces to the self-consistent estimate of Berryman (2005). The accuracy of the present method is first assessed using numerical, Fourier-based computations. In the absence of crystal anisotropy, the estimates for the effective elastic properties are close to that obtained numerically for a homogeneous body containing disk-shaped cracks, with Boolean spatial dispersion. Various other analytical estimates and bounds, that are available for homogeneous cracked bodies, are also considered and compared to the present approach. Second, the combined role of crystal anisotropy and micro-cracks is investigated analytically, specifically when the in-plane shear modulus of the crystal becomes zero. The cracks-density perco-lation threshold is found to diminish abruptly in this limit. This "advanced" percolation threshold is concomitant to the onset of large, weakly-loaded regions surrounding cracks in strongly-anisotropic crystals.
Domaines
Matériaux
Origine : Fichiers produits par l'(les) auteur(s)
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