For control applications involving small displacements and velocities, friction modeling and compensation can be very important. In particular, the modeling of presliding displacement (motion prior to fully developed slip) can play a pivotal role. In this paper, it is shown that existing single-state friction models exhibit a nonphysical drift phenomenon which results from modeling presliding a...

The plastic flow of a foam results from bubble rearrangements. We study their occurrence in experiments where a foam is forced to flow in 2D: around an obstacle; through a narrow hole; or sheared between rotating disks. We describe their orientation and frequency using a topological matrix defined in the companion paper (F. Graner, B. Dollet, C. Raufaste, and P. Marmottant, this issue, 25 (2008...

We report on large-scale non-equilibrium molecular dynamics (NEMD) simulations of shock wave compression in Ta single crystals. The atomic interactions are modeled via a recently developed and optimized embedded-atom method (EAM) potential for Ta, which reproduces the equation of state up to 200 GPa. We examined the elastic-plastic transition and shock wave structure for wave propagation along ...

The changes in elastic lattice-strain profiles and plastic zone around the fatigue crack in a compact-tension specimen were investigated during monotonic tensile loading and unloading cycles using neutron diffraction. Spatially-resolved strain measurements were performed on a 316 LN stainless steel to determine the in-plane (parallel to the loading direction) lattice-strain profiles ahead of th...

A new approach to the description of processes of plastic defonnation is developed. Within this approach, the evolution of a dislocation ensemble is detennined by both dislocation multiplication and dislocation transfonnations with both the processes occurring against the background of elastic stresses produced by the dislocation ensemble itself. Apart from the equations of detailed balance tha...

In this appendix, we list the expressions that characterize the response of an elastic-perfectly plastic solid with sinusoidal roughness to indentation by a rigid flat punch. The substrate is an elastic-perfectly plastic solid with Young’s modulus E, Poisson’s ratio ν and yield stress Y σ . The surface roughness has wavelength n λ and amplitude n g . In terms of these parameters, we define a ma...

Steady state axisymmetric deformations of an elastic perfectly plastic target being penetrated by a fast moving rigid cylindrical rod have been analyzed by the finite element method. The target is assumed to obey the yon Mises yield criterion and the associated flow rule. Contact between target and penetrator has been assumed to be smooth. A mixed formulation, in which two components of the vel...

The fundamentals of particle-particle adhesion for ultrafine particles (d < 10 μm) are presented using continuum mechanics approaches. The models for elastic (Hertz, Huber), elastic-adhesive (Derjaguin, Johnson, Maugis, Greenwood), viscoelastic (Yang), plastic-adhesive (Krupp, Molerus, Johnson, Maugis & Pollock) contact displacement response of a single, normal loaded, isotropic, smooth contact...

The paper deals with structural optimization of biomorphic microcellular ceramics invoking an elasto– plasticity with the von Mises yield criterion in the macroscopic model. The return mapping algorithms introduced by Simo and Ortiz in 1985 are applied for the numerical solution of the problem. The latter methods are computationally effective, robust and stable, and have recently become the mos...

We suggest a scalar model for deformation and flow of an amorphous material such as a foam or an emulsion. To describe elastic, plastic and viscous behaviours, we use three scalar variables: elastic deformation, plastic deformation rate and total deformation rate; and three material-specific parameters: shear modulus, yield deformation and viscosity. We obtain equations valid for different type...