Indentation

About: Indentation is a research topic. Over the lifetime, 13002 publications have been published within this topic receiving 340476 citations.

Indentation techniques for evaluating the fracture toughness of biomaterials and hard tissues

Abstract: Indentation techniques for assessing fracture toughness are attractive due to the simplicity and expediency of experiments, and because they potentially allow the characterization of both local and bulk fracture properties. Unfortunately, rarely have such techniques been proven to give accurate fracture toughness values. This is a concern, as such techniques are seeing increasing usage in the study of biomaterials and biological hard tissues. Four available indentation techniques are considered in the present article: the Vickers indentation fracture (VIF) test, the cube corner indentation fracture (CCIF) test, the Vickers crack opening displacement (VCOD) test and the interface indentation fracture (IIF) test. Each technique is discussed in terms of its suitability for assessing the absolute and relative toughness of materials or material interfaces based on the published literature on the topic. In general, the VIF and CCIF techniques are found to be poor for quantitatively evaluating toughness of any brittle material, and the large errors involved (approximately +/-50%) make their applicability as comparative techniques limited. Indeed, indentation toughness values must differ by at least by a factor of three to conclude a significant difference in actual toughness. Additionally, new experimental results are presented on using the CCIF test to evaluate the fracture resistance of human cortical bone. Those new results indicate that inducing cracking is difficult, and that the cracks that do form are embedded in the plastic zone of the indent, invalidating the use of linear elastic fracture mechanics based techniques for evaluating the toughness associated with those cracks. The VCOD test appears to be a good quantitative method for some glasses, but initial results suggest there may be problems associated with applying this technique to other brittle materials. Finally, the IIF technique should only be considered a comparative or semi-quantitative technique for comparing material interfaces and/or the neighboring materials.

New evidence for a pressure-induced phase transformation during the indentation of silicon

Abstract: Scanning electron micrographs of indents in (111) silicon reveal that a thin layer of material immediately adjacent to the indenter is plastically extruded. The fact that the material can be deformed in this way indicates that it has metallic-like mechanical properties. This is presented as new evidence that a pressure-induced phase transformation to the metallic state occurs during the indentation of silicon.

An Indentation Method for Measuring Matrix‐Fiber Frictional Stresses in Ceramic Composites

Abstract: A simple method for measuring frictional stresses between the mairix and individual fibers in a ceramic composite is described. A standard microhardness indenter is used to apply a force to the end of the fiber and depress it below the matrix surface. The frictional stress is calculated from measurement of the applied force and the amount of slipping between the fiber and matrix.