This study compared the fracture toughness values (KIC), which were derived from simplified techniques: the indentation fracture (IF), the indentation strength (IS), and fractographic approach to that from a standard testing using surface cracks in flexure (SCF). Forty bar specimens, twenty IPS Empress(®) Esthetic and twenty IPS e.max(®)Ceram were prepared. Ten specimens in each material were t...

This paper clarifies a common misunderstanding of the phase transformation in monocrystalline silicon under nanoindentation, namely that a pop-out represents the onset of a phase transition. Through a detailed investigation into the indentation-induced deformation of monocrystalline silicon using a Berkovich indenter, it was found that a pop-out does not correspond to the onset of the transform...

Average stress during shear bond testing, and deformation behaviour during nano-indentation testing were calculated for the bonding area as a bonding site for copolymerization with resin composite in dentine bonding systems. First average stress was calculated in the bonding area between bovine dentine and composite resin. Secondly, the plastic deformation zone size was calculated using an elas...

Atomic force microscopy is an established technique for probing the local elastic properties of materials at submicron scales. In some cases, linear elastic contact theories based on Hertzian and adhesive contact mechanics suffice to model the indentation process. However, at the large strains that are common in many nanoindentation experiments, the linear models become invalid. A force-indenta...

Scanning- and colloidal-probe atomic force microscopy were used to study the mechanical properties of poly(L-lysine)/hyaluronan (PLL/HA)(n) films as a function of indentation velocity and the number of polymer deposition steps n. The film thickness was determined by two independent AFM-based methods: scratch-and-scan and newly developed full-indentation. The advantages and disadvantages of both...

Viscoelastic mechanical properties of biological cells are commonly measured using atomic force microscope (AFM) dynamic indentation with spherical tips. A semiempirical analysis based on numerical simulation is built to determine the cell mechanical properties. It is shown that the existing analysis cannot reflect the accurate values of cell elastic/dynamic modulus due to the effects of substr...

Measurement of the strength of brittle materials, such as resin composites, is extremely difficult. Micro-indentation hardness testing is a convenient way of investigating the mechanical properties of a small volume of material. In this study, the mechanical properties of five commercially available flowable resin composites were investigated by the dynamic micro-indentation method. Additionall...

Due to the nature of their material properties, Calcium Fluoride (CaF2), Magnesium Fluoride (MgF2), and Potassium Dihydrogen Phosphate (KDP) are widely used for industrial purposes. A better understanding of the mechanical properties of these materials is of technological and scientific importance. The indentation nano-mechanical response of CaF2 (cubic), MgF2 (tetragonal), and KDP (tetragonal)...

An instrumented indentation method is developed for generating maps of time-dependent viscoelastic and time-independent plastic properties of polymeric materials. The method is based on a pyramidal indentation model consisting of two quadratic viscoelastic Kelvin-like elements and a quadratic plastic element in series. Closed-form solutions for indentation displacement under constant load and c...

BACKGROUND To evaluate the effect of Nd:YAG capsulotomy for posterior capsular opacification (PCO) on visualisation of the peripheral fundus with scleral indentation. METHODS Patients undergoing Nd:YAG capsulotomy for PCO were examined pre- and four weeks post- Nd:YAG capsulotomy. In order to give a quantitative measure of visualisation of the peripheral retina, a novel scalar measurement was...