A Knoop-Indentation Method for R-Curve Determination

Chapter

Abstract

The stable growth of indentation cracks during a bending test offers an interesting possibility to study the R-curve behaviour of ceramics. The suitability of Knoop crack for such crack growth experiments is investigated on a silicon nitride.

For a proper evaluation of crack growth data the dependence of the geometric correction factor Y and of the residual stress parameter χ on crack length and indentation load have to be taken into account. Methods are developed to determine Y and χ and their change with indentation load and crack length. The measurement of R-curves is possible if Y — and χ — values determined by these methods are used for the evaluation of crack growth data.

For the investigated material a slightly rising R-curve was determined. Because of the low crack length to indent diagonal ratio of Knoop cracks a lower limit of c = 120 μm was introduced to the experimental range covered with Knoop cracks in this material.

Keywords

Fracture Toughness Crack Length Silicon Nitride Indentation Load Stable Crack Growth 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer Science+Business Media New York 2002

Authors and Affiliations

  • T. Lube
    • 1
  1. 1.Department of Structural and Functional CeramicsUniversity of LeobenLeobenAustria

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