The Use of Sphere Indentation Experiments to Characterize Ceramic Damage Models

Abstract

Sphere impact experiments are used to calibrate and validate ceramic models that include statistical variability and/or scale effects in strength and toughness parameters. These dynamic experiments supplement traditional characterization experiments such as tension, triaxial compression, Brazilian, and plate impact, which are commonly used for ceramic model calibration. The fractured ceramic specimens are analyzed using sectioning, X‐ray computed tomography, microscopy, and other techniques. These experimental observations indicate that a predictive material model must incorporate a standard deviation in strength that varies with the nature of the loading. Methods of using the spherical indentation data to calibrate a statistical damage model are presented in which it is assumed that variability in strength is tied to microscale stress concentrations associated with microscale heterogeneity.

Mesoscale modeling of nonlinear elasticity and fracture in ceramic polycrystals under dynamic shear and compression

“…Weibull distributions are often used to characterize failure behavior of brittle solids, including polycrystalline ceramics (Warner et al, 2005;Brannon et al, 2007;Foulk and Vogler, 2010;Graham-Brady, 2010;Leavy et al, 2010). Let s P 0 denote an independent variable.…”

“…However, experiments do suggest that certain properties can strongly affect dynamic performance. These properties include hardness, elastic stiffness, fracture toughness, unconfined compressive strength, dynamic shear strength, and failure probabilities (e.g., Weibull parameters) (Sternberg, 1989;Shockey et al, 1990;Curran et al, 1993;Gailly and Espinosa, 2002;Ray et al, 2007;Leavy et al, 2010). Experiments indicate that ceramics exhibit an increase in shear strength with increasing compressive pressure or confinement (Heard and Cline, 1980;Chen and Ravichandran, 2000).…”

“…Of particular interest in the present study are the following physical phenomena: dependence of dynamic shear strength on pressure, sensitivity of peak strength to grain morphology and elastic anisotropy, and dependence of statistical variations in peak strength on specimen size (i.e., number of grains) and local material properties. Pressure-dependent strength statistics from mesoscale simulations can be used to provide parameters entering macroscopic constitutive models for ceramic material behavior incorporating statistical failure criteria (Brannon et al, 2007(Brannon et al, , 2009Leavy et al, 2010;Graham-Brady, 2010). This paper is structured as follows.…”

The phenomenological mechanochemistry of damage and radial cracking

“…Radial cracking is of a high practical importance in high-rate mechanics of solids and terminal ballistics, in particular (see, for instance, the publications [1][2][3][4] and references therein). Due to the efforts of many researchers, including Brannon, Leavy, LaSavia, Strack, Ramesh, and Tonge, among others, computer modeling techniques became capable of reproducing, remarkably well, various features of brittle fracture, observed in nature and engineering experiments (see, for instance, Fig.…”

Dynamic compressibility, shear strength, and fracture behavior of ceramic microstructures predicted from mesoscale models

“…Properties of importance in the ballistic loading regime include hardness, elastic stiffness, fracture toughness, unconfined compressive strength, dynamic shear strength, and failure probabilities [1][2][3][4][5][6]. The present work investigates two ceramic materials: silicon carbide (SiC) and aluminum oxynitride (AlON).…”