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...

The friction and adhesion between elastic bodies are strongly influenced by the roughness of the surfaces in contact. Here we develop a multiscale molecular dynamics approach to contact mechanics, which can be used also when the surfaces have roughness on many different length-scales, e.g., for self affine fractal surfaces. As an illustration we consider the contact between randomly rough surfa...

A new analytical model for spherical rough contacts, in the form of a set of relationships, is developed and solved numerically. It is shown that the maximum contact pressure is the parameter that specifies the contact pressure distribution. Simple correlations for calculating the maximum contact pressure and the radius of the macrocontact area as functions of the nondimensional parameters are ...

form, Problem P . Find fu; ; g such that 0 +K1 +K2 + C1v + S(v; ; ) = Q in V 0; Bv + Au + C2 + 4j(v; ; ; v) 3 f in E 0: Here f 2 E 0 and Q 2 V 0 are given by hf; wi = Z T 0 Z f(t)wi(t) dxdt + Z T 0 Z ij (t)wi;j(t) dxdt + Z T 0 Z N fN(t)wi(t)d dt; hQ; i = Z T 0 hq(t); (t)i dt Z T 0 Z 0(t) (t) dxdt Z T 0 Z C hR( (t) R(t)) (t)d dt Z T 0 Z kij ;i(t) ;j(t) dxdt; and 4j(v; ; ; w) denotes the partial ...

The goal of this study was to determine how well a medial meniscal allograft restores the normal contact mechanics of the medial tibial plateau at the time of implantation. We measured maximum pressure, mean pressure, and contact area of the intact human cadaveric knee, the knee after meniscectomy, the knee with the original meniscus removed and reimplanted as an autograft, and the knee with an...