Effective Elastic Moduli of Porous Ceramic Materials

Abstract

This paper compares the applicability of a few theoretical models for determining effective elastic moduli, using published experimental data on ceramic materials in a porosity range of 0 4 0 % and on a cellular material with a porosity of about 90%. As the experimental data for the effective Poisson's ratio involve a large scatter, a set of numerical experiments using the finite element method was carried out to obtain the variation of the effective Poisson's ratio with porosity. These variations show that the effective Poisson's ratio approaches 0.25 with increasing porosity, irrespective of the material Poisson's ratio. The effect of pore shapes on the effective elastic moduli and the Poisson's ratio has also been analyzed using FEM.

Failure Modes of Thin Supported Membranes

“…(The specified value is an estimate taking into account, that the support is highly porous, which has a strong impact on the modulus 8 ). Considering as an example a tube of 5 cm diameter and a required external pressure of 30 atm., the necessary support thickness deduced from the stability criterion is only 1,5 mm.…”

“…The maximum tensile stress in the plate for the present case will occur at r=a (at the plate periphery). It is given by: (7,8) Where N is the compressive load (per unit length) acting along the outer periphery of the plate. M max is the maximum moment of a plate subjected only to the lateral load, and fak is a "correction factor" taking into account the effect of the compression on the local curvature.…”

Whole cell mechanics of contractile fibroblasts: relations between effective cellular and extracellular matrix moduli

“…Bounding theorems dictate limits on the elastic response of the collagen as a function of the mechanical response of the deoxycholate-treated construct (appendix A). Estimates like those of Ramakrishnan & Arunachalam (1993) and Monte Carlo simulations like those of Roberts & Garboczi (2000) incorporate specific void shapes, and predict that the modulus of a deoxycholate-treated construct will disappear at a void (cell) volume fraction sufficiently large that void clusters coalesce, eliminating continuity in the collagen. Accurate estimates do not exist for composites containing dense concentrations of ellipsoidal or spherical inclusions.…”

Cooling and Annealing Effect on Indentation Response of Lead-Free Solder

“…To facilitate the legends of the figures, the as-machined condition, water quenched, furnace cooled conditions and annealing treatment are abbreviated as AM, WQ, FC and AN, respectively. As proposed by Ramakrishnan and Arunachalam [1993], Young's modulus E is related to the porosity θ in the form of Eq. (1).…”