We find that the classical failure criteria, i.e., maximum normal stress criterion, Tresca criterion, Mohr-Coulomb criterion, and von Mises criterion, cannot satisfactorily explain the tensile fracture behavior of the bulk metallic glass (BMG) materials. For a better description, we propose an ellipse criterion as a new failure criterion to unify the four classical criteria above and apply it t...

The purpose of this paper is to study the solutions to the Signorini problem with Coulomb friction (the so-called Coulomb problem). Some optimal a priori estimates are given and a uniqueness criterion is exhibited. Recently, nonuniqueness examples have been presented in the continuous framework. It is proven, here, that if a solutions satisfies a certain hypothesis on the tangential displacemen...

Abstract Wellbore instability issues represent the most critical problems in Iraq Southern fields. These problems, such as hole collapse, tight and stuck pipe result tremendous increasing nonproductive time (NPT) well costs. The present study introduced a calibrated three-dimensional mechanical earth model (3DMEM) for X-field South of Iraq. This post-drill can be used to conduct comprehensive g...

Contacts at the Coulomb threshold are unstable to tangential perturbations and thus contribute to failure at the microscopic level. How is such a local property related to global failure, beyond the effective picture given by a Mohr–Coulomb type failure criterion? Here, we use a simulated bed of frictional disks slowly tilted under the action of gravity to investigate the link between the avala...

The Graphene based single electron transistor (SET) as a coulomb blockade device need to be explored .It is a unique device for high-speed operation in a nano scale regime. A single electron transfers via the coulomb barriers, but its movement may be prevented by coulomb blockade, so its effect is investigated in this research. The conditions of coulomb blockade and its controlling factors such...

This paper discusses Coulomb failure criteria for brittle deformation of intact rock and fault gouge. Data are presented from laboratory experiments designed to identify the critical gouge layer thickness required to effect a transition from the standard Coulomb criterion to a modified failure law (referred to as Coulomb plasticity) appropriate for simple shear of a gouge layer. Experiments wer...

Coulomb friction is inevitable in every mechanical system with contact motion. When the mechanical system with Coulomb friction is under feedback control, it can destabilize the system by generating limit cycles. Controlled mechanical systems with ideal Coulomb friction can be viewed as a particular class of relay feedback systems characterized by the zero DC gain property and the positivity of...

We examine electrically and color neutral quark matter in β-equilibrium focusing on the possibility of mixed phases between different color superconducting phases. To that end we apply the Gibbs criterion to ensure phase equilibrium and discuss the external conditions under which these mixed phases can occur. Neglecting surface and Coulomb effects we find a rich structure of different mixed pha...