Journal ArticleDOI
A Critical Evaluation of Indentation Techniques for Measuring Fracture Toughness: I, Direct Crack Measurements
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In this paper, the application of indentation techniques to the evaluation of fracture toughness is examined critically, in two parts: the first part is focused on an approach which involves direct measurement of Vickers-produced radial cracks as a function of the indentation load.Abstract:
The application of indentation techniques to the evaluation of fracture toughness is examined critically, in two parts. In this first part, attention is focused on an approach which involves direct measurement of Vickers-produced radial cracks as a function of indentation load. A theoretical basis for the method is first established, in terms of elastic/plastic indentation fracture mechanics. It is thereby asserted that the key to the radial crack response lies in the residual component of the contact field. This residual term has important implications concerning the crack evolution, including the possibility of post indentation slow growth under environment-sensitive conditions. Fractographic observations of cracks in selected “reference” materials are used to determine the magnitude of this effect and to investigate other potential complications associated with departures from ideal indentation fracture behavior. The data from these observations provide a convenient calibration of the Indentation toughness equations for general application to other well-behaved ceramics. The technique is uniquely simple in procedure and economic in its use of material.read more
Citations
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Journal ArticleDOI
An improved technique for determining hardness and elastic modulus using load and displacement sensing indentation experiments
Warren C. Oliver,George M. Pharr +1 more
TL;DR: In this paper, the authors used a Berkovich indenter to determine hardness and elastic modulus from indentation load-displacement data, and showed that the curve of the curve is not linear, even in the initial stages of the unloading process.
Journal ArticleDOI
A Critical Evaluation of Indentation Techniques for Measuring Fracture Toughness: II, Strength Method
TL;DR: In this paper, the sharp-indentation technique of strength-test precracking for toughness evaluation is examined and the residual-stress term discussed in Part I of this study is now introduced explicitly into the strength formulation.
Journal ArticleDOI
The search for novel, superhard materials
TL;DR: The recent development in the field of superhard materials with Vickers hardness of ⩾40 GPa is reviewed in this article, where two basic approaches are outlined including the intrinsic superhard material, such as diamond, cubic boron nitride, C3N4, carbonitrides, etc. and extrinsic, nanostructured materials for which superhardness is achieved by an appropriate design of their microstructure.
Journal ArticleDOI
Measurement of mechanical properties by ultra-low load indentation
TL;DR: In this paper, the use of sharp indenters and how they can be used to measure elastic modulus, hardness, and fracture toughness is discussed, which characterize the three primary modes of deformation in solids.
Journal ArticleDOI
Single-wall carbon nanotubes as attractive toughening agents in alumina-based nanocomposites
TL;DR: This work fabricated fully dense nanocomposites of single-wall carbon nanotubes with nanocrystalline alumina (Al2O3) matrix at sintering temperatures as low as 1,150 °C by spark-plasma sintered, demonstrating their potential use in reinforcing nanocrystaline ceramics.
References
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Journal ArticleDOI
Fracture Toughness Determinations by Indentation
Anthony G. Evans,E. A. Charles +1 more
Journal ArticleDOI
Elastic/Plastic Indentation Damage in Ceramics: The Median/Radial Crack System
TL;DR: In this article, a theory for describing the evolution of the median/radial crack system in the far field of sharp-indenter contacts is developed, based on a model in which the complex elastic/plastic field beneath the indenter is resolved into elastic and residual components.
Journal ArticleDOI
Indentation fracture: principles and applications
Brian R. Lawn,Rodney Wilshaw +1 more
TL;DR: The basic principles and practical applications of indentation fracture are reviewed in this article, with a focus on the application of fracture fracture in the field of orthogonal fracture repair and alignment.
Journal ArticleDOI
A Critical Evaluation of Indentation Techniques for Measuring Fracture Toughness: II, Strength Method
TL;DR: In this paper, the sharp-indentation technique of strength-test precracking for toughness evaluation is examined and the residual-stress term discussed in Part I of this study is now introduced explicitly into the strength formulation.
Journal ArticleDOI
Quasi-static solid particle damage in brittle solids—I. Observations analysis and implications
Anthony G. Evans,T.R. Wilshaw +1 more
TL;DR: In this paper, an approximate stress analysis has indicated the importance of both the impression radius and the ratio of the hardness to the fracture toughness in the development of the observed fractures, which has been used to examine several important consequences of indentation fracture.
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