TU Darmstadt / ULB / TUbiblio

Fracture mechanics model for subthreshold indentation flaws: I: Equilibrum Fracture

Lathabai, Srinivasarao and Rödel, Jürgen and Dabbs, T. and Lawn, B. R. (1991):
Fracture mechanics model for subthreshold indentation flaws: I: Equilibrum Fracture.
In: Journal of Materials Science, pp. 2157-2168, 26, (8), ISSN 0022-2461, [Online-Edition: http://dx.doi.org/10.1007/BF00549183],
[Article]

Abstract

A fracture mechanics model for subthreshold indentation flaws is. described. The model describes the initiation and extension of a microcrack from a discrete deformation-induced shear ldquofaultrdquo (shear crack) within the contact zone. A stress-intensity factor analysis for the microcrack extension in residual-contact and applied-stress fields is used in conjunction with appropriate fracture conditions, equilibrium in Part I and non-equilibrium in Part II, to determine critical instability configurations. In Part I, the K-field relations are used in conjunction with the Griffith requirements for crack equilibrium in essentially inert environments to determine: (i) the critical indentation size (or load) for spontaneous radial crack pop-in from a critical shear fault under the action of residual stresses alone; (ii) the inert strengths of surfaces with subthreshold or postthreshold flaws. The theory is fitted to literature data for silicate glasses. These fits are used to ldquocalibraterdquo dimensionless parameters in the fracture mechanics expressions, for later use in Part II. The universality of the analysis in its facility to predict the main features of crack initiation and propagation in residual and applied fields will be demonstrated. Special emphasis is placed on the capacity to account for the significant increase in strength (and associated scatter) observed on passing from the postthreshold to the subthreshold domain.

Item Type: Article
Erschienen: 1991
Creators: Lathabai, Srinivasarao and Rödel, Jürgen and Dabbs, T. and Lawn, B. R.
Title: Fracture mechanics model for subthreshold indentation flaws: I: Equilibrum Fracture
Language: English
Abstract:

A fracture mechanics model for subthreshold indentation flaws is. described. The model describes the initiation and extension of a microcrack from a discrete deformation-induced shear ldquofaultrdquo (shear crack) within the contact zone. A stress-intensity factor analysis for the microcrack extension in residual-contact and applied-stress fields is used in conjunction with appropriate fracture conditions, equilibrium in Part I and non-equilibrium in Part II, to determine critical instability configurations. In Part I, the K-field relations are used in conjunction with the Griffith requirements for crack equilibrium in essentially inert environments to determine: (i) the critical indentation size (or load) for spontaneous radial crack pop-in from a critical shear fault under the action of residual stresses alone; (ii) the inert strengths of surfaces with subthreshold or postthreshold flaws. The theory is fitted to literature data for silicate glasses. These fits are used to ldquocalibraterdquo dimensionless parameters in the fracture mechanics expressions, for later use in Part II. The universality of the analysis in its facility to predict the main features of crack initiation and propagation in residual and applied fields will be demonstrated. Special emphasis is placed on the capacity to account for the significant increase in strength (and associated scatter) observed on passing from the postthreshold to the subthreshold domain.

Journal or Publication Title: Journal of Materials Science
Volume: 26
Number: 8
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Nonmetallic-Inorganic Materials
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences
Date Deposited: 13 Jun 2012 13:31
Official URL: http://dx.doi.org/10.1007/BF00549183
Identification Number: doi:10.1007/BF00549183
Export:

Optionen (nur für Redakteure)

View Item View Item