Numerical modeling of carbon/carbon composites with nanotextured matrix and 3D pores of irregular shapes

Abstract

a b s t r a c tA multiscale modeling approach is utilized to evaluate the contribution of irregularly shaped threedimensional pores to the overall elastic properties of carbon/carbon composites. The degree of anisotropy of a carbon matrix depends on nanotexture, which is defined by manufacturing conditions. Elastic properties of the matrix are predicted assuming a Fisher distribution of orientations of graphene planes with respect to the pyrolytic carbon deposition direction. X-ray computed microtomography is employed to identify pores in a sample of carbon/carbon composite. The pores have highly irregular shapes so that micromechanical modeling based on the analytical solutions of elasticity becomes inapplicable. Thus, the cavity compliance tensor of an individual pore is found numerically by finite element method, and then used in a micromechanical modeling procedure. Examples of pores in isotropic and transversely isotropic pyrolytic carbon matrices are considered. The accuracy of pore approximation by ellipsoidal shapes is evaluated.

Nanoscale elasticity of highly anisotropic pyrocarbons

“…C/C composites are usually obtained through the deposition of a carbon matrix on a carbon fiber cloth, using different possible chemical routes, from gas or liquid precursors. Understanding the mechanical and thermal behavior of such composite materials is not straightforward and usually requires multiscale models in which the materials scale is described using finite element methods considering effective properties for the fibers and matrix as well as mean field theories [1][2][3][4]. Properties of the fibers, both mechanical and thermal, are extremely well documented in the literature due to the possibility of directly performing the measurements on single filaments.…”

Micropore Structures in Cenosphere-Containing Cementitious Materials Using Micro-CT

“…Drach et al developed the 4-factor PCC model to evaluate the influence of micropores on elastic moduli including Young's modulus ( ), bulk modulus ( ), and shear modulus ( ) [16,18]. 4-factor PCC is a statistical model to give a prediction from input variables obtained from variation in irregular pore geometries.…”

Effective stiffness and thermal expansion coefficients of unidirectional composites with fibers surrounded by cylindrically orthotropic matrix layers

“…We consider a unidirectional bundle of carbon fibers surrounded by multiple layers of PyC in the absence of pores (Note that contribution of pores to the effective response of various materials can be found in Drach et al, 2011;Kachanov, Tsukrov, & Shafiro, 1994;Levin, Lokhin, & Zingerman, 2000;Zimmerman, 1991b). All constituents, fiber and various types of PyC, can be either isotropic or transversely isotropic with respect to fiber axis (TI À z), or cylindrically orthotropic.…”