arXiv subjects

Michael Urbakh

Publications and source records attributed to Michael Urbakh.

42 records · Page 3Linked to original sources

arXiv2011

Stabilizing stick-slip friction

Even the most regular stick-slip frictional sliding is always stochastic, with irregularity in both the intervals between slip events and the sizes of the associated stress drops. Applying small-amplitude oscillations to the shear force, we show, experimentally and theoretically, that the stick-slip periods synchronize. We further show that this phase-locking is related to the inhibition of slow rupture modes which forces a transition to fast rupture, providing a possible mechanism for observed remote triggering of earthquakes. Such manipulation of collective modes may be generally relevant to extended nonlinear systems driven near to criticality.

cond-mat.soft↗

arXiv2011

Cracklike Dynamics at the Onset of Frictional Sliding

We propose an elasto-plastic inspired friction model which incorporates interfacial stiffness. Steady state sliding friction is characterized by a generic nonmonotonic behavior, including both velocity weakening and strengthening branches. In 1D and upon the application of sideway loading, we demonstrate the existence of transient cracklike fronts whose velocity is independent of sound speed, which we propose to be analogous to the recently discovered slow interfacial rupture fronts. Most importantly, the properties of these transient inhomogeneously loaded fronts are determined by steady state front solutions at the {\em minimum} of the sliding friction law, implying the existence of a new velocity scale and a "forbidden gap" of rupture velocities. We highlight the role played by interfacial stiffness and supplement our analysis with 2D scaling arguments.

cond-mat.mtrl-sci↗

arXiv2007

Manipulating single enzymes by an external harmonic force

We study a Michaelis-Menten reaction for a single two-state enzyme molecule, whose transition rates between the two conformations are modulated by an harmonically oscillating external force. In particular, we obtain a range of optimal driving frequencies for changing the conformation of the enzyme thereby controlling the enzymatic activity (i.e. product formation). This analysis demonstrates that it is, in principle, possible to obtain information about particular rates within the kinetic scheme.

q-bio.BM↗

arXiv2000

Atomic scale engines: Cars and wheels

We introduce a new approach to build microscopic engines on the atomic scale that move translationally or rotationally and can perform useful functions such as pulling of a cargo. Characteristic of these engines is the possibility to determine dynamically the directionality of the motion. The approach is based on the transformation of the fed energy to directed motion through a dynamical competition between the intrinsic lengths of the moving object and the supporting carrier.

cond-mat↗

arXiv2000

Molecular motor that never steps backwards

We investigate the dynamics of a classical particle in a one-dimensional two-wave potential composed of two periodic potentials, that are time-independent and of the same amplitude and periodicity. One of the periodic potentials is externally driven and performs a translational motion with respect to the other. It is shown that if one of the potentials is of the ratchet type, translation of the potential in a given direction leads to motion of the particle in the same direction, whereas translation in the opposite direction leaves the particle localized at its original location. Moreover, even if the translation is random, but still has a finite velocity, an efficient directed transport of the particle occurs.

cond-mat↗

arXiv1999

Looking at friction through "shearons"

We study the response to shear of a one-dimensional monolayer embedded between two rigid plates, where the upper one is externally driven. The shear is shown to excite ``shearons'', which are collective modes of the embedded system with well defined spatial and temporal pattern, and which dominate the frictional properties of the driven system. We demonstrate that static friction, stick-slip events, and memory effects are well described in terms of the creation and/or annihilation of a shearon. This raises the possibility to control friction by modifying the excited shearon, which we examplify by introducing a defect at the bottom plate.

cond-mat.stat-mech↗