Micromechanical estimate of the elastic properties of the coherent domains in pyrolytic carbon

On the nanoscale, the microstructure of pyrolytic carbon (PyC) is constituted by an ensemble of graphene planes, which manifest themselves as lattice fringes in high-resolution transmission electron microscope images. This microstructure can be also considered by an aggregate of so-called coherent domains consisting of stacks of graphene planes with a common unit normal vector. In order to homogenize the elastic behavior of PyC on the micro-level, image processing techniques are used to detect the coherent domains. Subsequently, the domain orientation distribution function (DODF) is modeled by means of a von Mises-Fisher distribution. The main objective of the present paper is to estimate the elastic properties of the coherent domains of the PyC microstructure. Moreover, the Hashin-Shtrikman bounds for the elastic properties can be determined by taking into account the DODF and by applying a nonlinear averaging procedure of the spatially dependent deviations of the local elastic properties. The elastic properties of the coherent domains are estimated by an inverse parameter identification of the Hashin-Shtrikman homogenization method by using effective elastic properties. The latter ones have been obtained based on an Fourier-based image processing algorithm and the orientation distribution function of the graphene planes in a recent paper (Bohlke et al. in Z Angew Math Mech, 2012).