Cell contraction force plays an important role in wound healing, inflammation,angiogenesis and metastasis. This study describes a novel method to quantify single cell contraction force in vitro using human aortic adventitial fibroblasts embedded in a collagen gel. The technique is based on a depth sensing nano-indentation tester to measure the thickness and elasticity of collagen gels containin...

This study investigates the influence of stimulus properties on explorative movement parameters in active touch. Using a PHANToM force-feedback device we generated virtual stimuli with different stiffness values. Participants freely explored pair-wise presented stimuli and were asked to select the softer one. Afterwards we analyzed their explorative movements considering the parameters velocity...

Instrumented indentation test has been extensively applied to study the mechanical properties such as elastic modulus of different materials. The Oliver–Pharr method to measure the elastic modulus from an indentation test was originally developed for single phase materials. During a spherical indentation test on shape memory alloys (SMAs), both austenite and martensite phases exist and evolve i...

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...

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...

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...