Fracture Toughness Effects in Geomaterial Solid Particle Erosion

Abstract

Effects of fracture toughness on the impingement of geomaterials (rocks and cementitious composites) by quartz particles at velocities between 40 and 140 m/s are investigated experimentally and analytically. If schist is excluded, relative erosion (in g/g) reduces according to a reverse power function if fracture toughness increases. The power exponent depends on impingement velocity, and it varies between -0.64 and -1.33. Lateral cracking erosion models, developed for brittle materials, deliver too high values for relative material erosion. This discrepancy is partly attributed to stress rate effects. Effects of R-curve behavior seem to be marginal. An integral approach E R = K 1 Á E R P ? (1 -K 1 ) Á E R L is introduced, which considers erosion due to plastic deformation and lateral cracking. A transition functionsuggested in order to classify geomaterials according to their response against solid particle impingement.

A transition function for the solid particle erosion of rocks

“…Because lance formation occurs under localized mixed loading regimes, these particular features support an approach of a mode-II crack propagation mode being active during lateral crack formation due to solid particle impingement [14]. The results also support the conclusion drawn in [8], that erosion of rocks due to solid particle impingement is insensitive to mode-I R-curve behaviour. In general, features of brittle fracture dominate the material removal process on the microscopic scale.…”

“…Similar to Fig. 1d, these features confirm a mixed loading regime as well as the insensitivity of the erosion process to mode-I Rcurve behaviour [8]. In general, brittle fracture features dominate the material removal process on the microscopic scale.…”

“…(3) because of its higher power exponent. For the three frame conditions: (i) K 1 ¼0 for χ ¼0; (ii) K 1 ¼1 for very high χ-numbers; (iii) inflection point between erosion modes, the relationship between χ and K 1 can be approximated with a two-parameter Weibull distribution function [8] …”

Solid Particle Erosion of a Limestone Target Surface under Controlled Conditions

“…Following the literature [23], we estimated the mass of eroded material in individual bead impacts according to a model based on impact-induced crack formation in brittle solids [34]. e model expresses the mass loss as…”

“…e volume of eroded material increases with the impinging particle diameter [19,20], and local heating processes can be inferred from schist SPE [21,22]. In addition, the increase in fracture toughness reduces relative erosion according to a reverse power law that is affected by the impingement velocity [23].…”