Elastic/Plastic Indentation Damage in Ceramics: The Lateral Crack System

TLDR

Lateral crack propagation in sharp‑indenter contacts is governed by the mechanics of the elastic/plastic field, with the hardness‑to‑modulus ratio complementing toughness as in median/radial crack systems. The study aims to predict lateral fracture extent in ceramics to provide a basis for analyzing surface erosion. The authors derive equilibrium crack evolution expressions based on the residual elastic/plastic field that dominates during unloading, accounting for crack‑plane proximity to the free surface, and test the resulting predictions against experimental lateral crack measurements across diverse ceramics. Experimental measurements of lateral crack dimensions across ceramics confirm the theory’s predictions.

Abstract

The mechanics of lateral crack propagation in a sharp‐indenter contact field are described. The driving force for fracture has its origin in the residual component of the elastic/plastic field, which becomes dominant as the indenter is unloaded. Expressions for equilibrium crack evolution are derived, with due allowance for the close proximity of crack plane and specimen free surface. As with the median/radial crack system considered in an earlier paper, the ratio hardness‐to‐modulus complements toughness in the fracture relations. The basic predictions of the theory are examined in terms of experimental measurements of lateral crack dimensions in materials with a wide range of mechanical properties. The prospects of predicting the extent of lateral fracture in other ceramics, and thence of establishing a base for analyzing such important practical properties as surface erosion, are discussed.