One of the primary features of nano-indentation technique is that the contact area induced by an indenter is indirectly measured by a relationship between the penetration depth and the known geometry of the indenter. However, this indirect measurement occasionally leads to inaccurate properties of the indented material. The objective of this study is to investigate the effects of E/σr and the s...

This study is aimed to develop a novel noncontact ultrasonic indentation system for measuring quantitative mechanical properties of soft tissues, which are increasingly important for tissue assessment and characterization. The key idea of this method is to use a water jet as an indenter to compress the soft tissue while at the same time as a medium for an ultrasound beam to propagate through. T...

Detecting and localizing hard lumps in soft tissues is an important medical procedure. A psychophysics experiment measured minimum indentation forces required to detect a hard ball embedded in a soft rubber model. Ball size and finger indentation speed were varied. Threshold detection forces increased with ball size and decreased with indentation speed. The shape of the finger and contact press...

Nix and Gao established an important relation between microindentation hardness and indentation depth. Such a relation has been verified by many microindentation experiments (indentation depths in the micrometer range), but it does not always hold in nanoindentation experiments (indentation depths approaching the nanometer range). We have developed a unified computational model for both microan...

Ti-TiC-TiC/diamond-like carbon (DLC) gradient nano-composite films have been prepared on NiTi alloy substrates by the technique of plasma immersion ion implantation and deposition (PIIID) combined with plasma-enhanced chemical vapor deposition (PECVD). The influence of negative bias voltage applied to the substrate (from -100 V to -500 V) on the chemical structure, microstructure, mechanical pr...

The indentation slope curve from a spherical indentation on elastic-plastic materials is examined. By comparing it with that of an linear elastic material of the same elastic properties, we found that the start point of plastic yielding for an elastic-plastic material can be easily located from the indentation slope curve. Based on this analysis, a simple but effective method is proposed tomeas...

Indentation methods are finding increasing use in the study of mechanical properties of bulk and thin-film materials over a wide range of size scales (e.g., [1,2]). With the increasing sophistication of instrumented, depth-sensing indentation equipment and of computational methods to model the deformation of materials subjected to indentation, there is growing interest in studying the elastopla...

This paper presents a flexible, vision-based test setup to perform 3D measurements of thin, sheet-like structures and indentation trials to obtain geometric properties and stiffness maps of biological soft tissues. The system is utilized for in vitro testing of cartilage-bone plugs to acquire a “gold standard” which will be used to validate MRI measurements of cartilage properties.