Issue 24

P.V. Makarov et alii, Frattura ed Integrità Strutturale, 24 (2013) 127-137; DOI: 10.3221/IGF-ESIS.24.14 127 Special Issue: Russian Fracture Mechanics School The numerical simulation of ceramic composites failure at axial compression P.V. Makarov, M.O. Eremin Institute of Strength Physics and Material Science Siberian Branch of Russian Academy of Science, National Researching Tomsk State University bacardi@sibmail.com A BSTRACT . On the basis of the developed model of quasibrittle medium the brittle and quasibrittle failure of composite ceramic materials with zirconium dioxide matrix and various percentage of hardening particles of corundum are studied numerically. The theory of the damaged media is applied in the calculations. It is shown that failure process educes in 2 stages - a relatively slow quasistationary phase of accumulation of inelastic deformations and damages in all hierarchy of scales and superfast catastrophic phase - a blow-up regime when the failure process reaches the macro-scale and there is a macro-crack formation. The failure process in the proposed model assumes to be completed when the damage function reaches its maximum value and the strength of the composite evolve to zero. K EYWORDS . Brittle and quasi-brittle failure; Quasistationary phase; Blow-up regime. I NTRODUCTION onstructional ceramic composites have received a wide practical application in the industry because of their high unit strength, the raised toughness, hardness, crack stability, high resistivity to fatigue breakdown etc. Constructional ceramics on the basis of strong oxides of various metals (zirconium, aluminum, etc.) are capable to resist the intensive mechanical loads effectively. However the brittle properties of ceramic composites, their rather low stability to shock loads strongly confine the ranges of their application. Studying the mechanisms and features of brittle and quasibrittle failure of ceramic materials is one of the most urgent problems of modern fracture mechanics. According to the approach of physical mesomechanics [1] and ideas of paper [2] the loaded solid is the nonlinear dynamic system which evolution in fields of operating forces completely corresponds to the fundamental features of evolution of nonlinear dynamic systems. In the present paper the basic attention is given to the character of failure of quasibrittle solids and media – the presence of two stages of failure: rather slow quasistationary and superfast catastrophic stage – the blow-up regime according to the S.P. Kurdyumov terminology [3] as it is the fundamental feature of evolution of the nonlinear dynamic systems possessing the self-organized criticality [4]. One of the central problems of solid mechanics is a problem of the formulation of the fracture criteria or conditions when the crack formation starts. Many papers are dedicated to the problems of crack-growing in non-homogeneous media, such as rocks [19], polycrystalline materials or ceramics and ceramic composites [18]. For example, in paper [21] the equation of state is built on the basis of crack interaction and crack density accounting and strain rate dependency and used for simulation of macroscopic stress-strain curves. Such approach gives good qualitative and quantitative results in calculation of the degradation stage in stress-strain curves, strain rate dependency and defects density evolution. However C