Specimens of the SA508-IV reactor pressure vessel (RPV) steel, containing 3.26 wt. % Ni and just 0.041 wt. % Cu, were irradiated at 290 ◦C to different displacement per atom (dpa) with 3.5 MeV Fe ions (Fe2+). Microstructure observation and nano-indentation hardness measurements were carried out. The Continuous Stiffness Measurement (CSM) of nano-indentation was used to obtain the indentation de...

Thin shells are found in nature at scales ranging from viruses to hens' eggs; the stiffness of such shells is essential for their function. We present the results of numerical simulations and theoretical analyses for the indentation of ellipsoidal and cylindrical elastic shells, considering both pressurized and unpressurized shells. We provide a theoretical foundation for the experimental findi...

Nanoindentation tests using the Berkovich indenter tip were performed on 50 and 200 nm thick polycrystalline gold films deposited on hard substrates. Gold film hardness increased with the indentation depth due to the influence of the substrate. A procedure based on the Joslin-Oliver method was introduced to correct for the substrate effect. The method utilizes the fact that the measured elastic...

Mechanical properties and deformation of the vertically aligned carbon nanotube arrays (VA-CNTs) has been examined with large-displacement indentation tests inside a scanning electronic microscope (SEM). The in-situ indentation allows for establishment of the load-depth responses and real-time observations of the deformation processes. Under a cylindrical, flat indenter, the VA-CNTs exhibit ela...

We derive an expression relating the axial load, the indentation depth, and the elastic constants of an orthotropic material, and simplify it to that for a cubic material (e.g., an FCC single crystal). We use this formula and results of three virtual (i.e., numerical) indentation tests on the same specimen oriented differently to find values of the elastic moduli, and show that they agree well ...

Multimillion-atom molecular dynamics simulation of indentation of nanocrystalline silicon carbide reveals unusual deformation mechanisms in brittle nanophase materials, resulting from the coexistence of brittle grains and soft amorphous grain boundary phases. Simulations predict a crossover from intergranular continuous deformation to intragrain discrete deformation at a critical indentation de...

The indentation test is a popular experimental method to measure a material’s mechanical properties such as elastic modulus and hardness, and the Oliver–Pharr method is commonly used in commercial indentation instruments to obtain these two quantities. To apply the Oliver–Pharr method correctly in all of these cases, it is essential to know the limitations of this method. The present study focu...

The localized loading of an elastic sheet floating on a liquid bath occurs at scales from a frog sitting on a lily pad to a volcano supported by the Earth's tectonic plates. The load is supported by a combination of the stresses within the sheet (which may include applied tensions from, for example, surface tension) and the hydrostatic pressure in the liquid. At the same time, the sheet deforms...

background: the aim of this study was to compare the effects of conventional acid etching and laser etching on the nano-mechanical properties of the dental enamel using nano-indentation test. materials and methods: in this experimental in vitro study, buccal surfaces of 10 premolars were divided into three regions. one of the regions was etched with 37% phosphoric acid and another etched with e...

We report on quantifiable depth-dependent contact resonance AFM (CR-AFM) measurements over polystyrene-polypropylene (PS-PP) blends to detail surface and sub-surface features in terms of elastic modulus and mechanical dissipation. The depth-dependences of the measured parameters were analyzed to generate cross-sectional images of tomographic reconstructions. Through a suitable normalization of ...