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

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 medianhadial 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.

Solid particle erosion mechanisms of protective coatings for aerospace applications

“…One such relationship is the H/E ratio which has been shown by Leyland and Matthews [19] to be descriptive of several mechanical contact situations related to tribological processes. In fact, it can be found in several of the models proposed to calculate fracture toughness by sharp probe indentation, most notably in the work by Lawn and coworkers [20][21][22]. It has also been shown to be an indicator of surface resistance to sliding wear [23,24] of coated surfaces, and to be an important predictor of the amount of energy dissipated through plastic deformation during indentation [25,26].…”

“…In addition, the depth from which the lateral cracks are believed to propagate is below the plastic zone and not at the maximum depth of penetration. In order to correct these two deficiencies, Buijs [68] refined the quasi-static model by using the lateral fracture system analysis proposed by Marshal et al [21]. The approach was later expanded by Slikkerveer et al [69] using a more complex representation of the lateral crack system.…”

“…[71] elaborated on this approach and developed analytical expressions that predict these transitions in material behavior. They based their work on the analytical indentation models proposed by Wiederhorn and Lawn [72] for cone cracks, Lawn et al [20] for the median/radial crack system and Marshall et al [21] for the lateral crack system. They expressed the transition thresholds as critical velocities (V crit ) for a given particle size at which transition will occur.…”

“…Based on the work by Marshall, Lawn and Evans [20,21,197,201], several indentation-based analytical models have been developed for the SPE by lateral fracture, among which both Evans [66] and Wiederhorn et al [202] proposed interpretations based on elasto-plastic indentation. The former adopted a dynamic approach for the calculation of the particle penetration depth and the maximum applied load while the latter used a quasi-static approach where the particle's KE is transferred to the target by the work of indentation.…”

“…The former adopted a dynamic approach for the calculation of the particle penetration depth and the maximum applied load while the latter used a quasi-static approach where the particle's KE is transferred to the target by the work of indentation. In a series of more recent papers, Buijs [68] and Slikkerveer et al [69] further developed the quasi-static model by using the analytical model for lateral fracture originally developed by Marshall et al [21].…”