Nanoindentation testing of compliant materials has recently attracted substantial attention. However, nanoindentation is not readily applicable to softer materials, as numerous challenges remain to be overcome. One key concern is the significant effect of adhesion between the indenter tip and the sample, leading to larger contact areas and higher contact stiffness for a given applied force rela...

Cohesion effects are of prime importance in powders and granular media, and they are strongly affected by the roughness of the grain surface. We report measurements of the adhesion force between surfaces of Pyrex having a nanometric roughness, with a surface force apparatus. The two surfaces are immersed in liquid n-dodecane. The adhesion force measured is much smaller than expected in the case...

Dynamic simulations of wave propagation are performed in dense granular media with a narrow polydisperse size-distribution and a linear contact-force law. A small perturbation is created on one side of a static packing and its propagation, for both P- and S-waves, is examined. A size variation comparable to the typical contact deformation already changes sound propagation considerably. The tran...

Relaxation indentation experiments using atomic force microscopy (AFM) are used to obtain viscoelastic material properties of soft samples. The quasilinear viscoelastic (QLV) model formulated by Fung (1972, "Stress Strain History Relations of Soft Tissues in Simple Elongation," in Biomechanics, Its Foundation and Objectives, Prentice-Hall, Englewood Cliffs, NJ, pp. 181-207) for uniaxial compres...

We modify the formulation of Hertz contact theory between two elastic half-solids with axial symmetry and show that these modifications to Hertz's original framework allow the development of force laws of the form F [Please see symbol] z(n), 1 < n < ∞, where F is the force and z is the distance between the centers of the two solids. The study suggests that it may be possible to design physical ...

A study of four constitutive contact models employed in discrete element analysis is presented. Most discrete element simulations employ simple contact models due to computational time constraints. However, few works are available in literature which evaluates the suitability of these simple models to simulate DEM applications. The influence of more complex models on bulk behavior is examined t...