Hertz contact theory has been widely used for the determination of cell elasticity based on AFM indentation experiments. In light of the adhesive contact between AFM tip and cell, this study applied Johnson-Kendall-Roberts (JKR) model to fit the indentation force-displacement (F-D) curves reported previously. A MIN6 cell has been modeled as first a sphere and then a flattened cell with differen...

INTRODUCTION The raster scanning and nanoindentation capabilities of the AFM are exploited in force spectroscopy, a valuable quantitative technique for mapping the elastic properties of materials down to nanometer resolution. When the probe is of well-defined geometry and the indentation behavior can be represented by established contact mechanics models, the force maps can be transformed to el...

A comprehensive study on the spherical indentation of hyperelastic soft materials is carried out through combined theoretical, computational, and experimental efforts. Four widely used hyperelastic constitutive models are studied, including neo-Hookean, Mooney-Rivlin, Fung, and Arruda-Boyce models. Through dimensional analysis and finite element simulations, we establish the explicit relations ...

The finite-element method is used to perform an accurate numerical study of the normal indentation of an elastic-plastic half-space by a rigid sphere. The effects of elasticity and strain-hardening rate of the half-space are explored, and the role of friction is assessed by analysing the limiting cases of frictionless contact and sticking friction. Indentation maps are constructed with axes of ...

We consider the effect of an elastic modulus that decreases with depth on the load-displacement relation for indentation of a graded half space by a rigid indenter. A closed-form approximation incorporating features of the plate on an elastic substrate and the Hertzian contact theory is compared with finite element results for the case of a uniform stiff layer on a homogeneous substrate. Some g...

We explore the collective mechanical behavior of monolayer assemblies composed of close-packed arrays of hollow silica nanoparticles using a spherical nanoindentor. Seven types of well-defined hollow nanoparticles are studied with their radii ranging from 100 to 300 nm and shell thickness ranging from 14 to 44 nm. Micromechanical models reveal the underlying deformation mechanisms during indent...

The problem of a low-velocity normal impact rigid sphere upon an infinite viscoelastic Kirhhoff-Love plate is considered. dynamic behaviour the described by fractional derivative standard linear solid model. parameter defining order governs variation in viscosity plate’s material within contact domain during process. local bearing under sphere’s indentation, as well force are defined via genera...

Using atomic force microscopy we have studied the nanomechanical response to nanoindentations of surfaces of highly oriented molecular organic thin films (thickness<1000 nm). The Young’s modulus E can be estimated from the elastic deformation using Hertzian mechanics. For the quasi-one-dimensional metal tetrathiafulvalene tetracyanoquinodimethane E;20 GPa and for the a phase of the p-nitropheny...