arXiv subjects

Eduardo A. Jagla

Publications and source records attributed to Eduardo A. Jagla.

8 recordsLinked to original sources

arXiv2026

Nonholonomic constraints at finite temperature

We investigate the behavior of dynamical systems with nonholonomic constraints when coupled to a thermal bath, focusing on the paradigmatic case of the Chaplygin sleigh. A straightforward Langevin-type approach obtained by naively adding stochastic and dissipative terms to the equations of motion predicts a regime in which useful work can be extracted, violating the second law of thermodynamics. To resolve this paradox, we resort to a physically motivated implementation of the nonholonomic constraint as the limiting case of a viscous interaction. However, at finite temperature, fluctuation-dissipation relations imply that the viscous force has to be complemented with stochastic forces acting at the contact. We show that their incorporation restores compliance with the second law. Therefore, our results place fundamental limits on the physical realizability of idealized nonholonomic constraints.

cond-mat.stat-mech↗

arXiv2025

Common principles behind rainbows and boat wakes

Rainbows and boat wakes may seem unrelated, but they share deep mathematical connections through ray folding, caustics, and Airy interference. This paper explores these principles, which are also relevant for explaining phenomena such as shimmering effects on the bottom of pools and twinkling stars. By revisiting Airy's theories on wavefronts and caustics, we demonstrate their applications not only in optics and for water waves but also in quantum wave packets. Using concepts from undergraduate physics, we highlight the universal patterns that unify these diverse phenomena.

physics.pop-ph↗

arXiv2025

Soil creep facilitated by cyclic variations of environmental conditions

Sloped terrains tend to creep downward over time, even when their slope is below the nominal angle of repose. This behavior can result from periodic variations in environmental conditions, such as daily or seasonal fluctuations in temperature and humidity. We study this process by considering a model of an athermal yield stress material under an applied stress lower than the critical yield stress value $σ_c$. Normally, in such a situation the material does not flow at all. However, under cyclic temporal variation of system parameters a finite amount of irreversible deformation can remain after each cycle, and a long term steady-state flow of the whole system can be induced. In our model, we cycle the strength of internal elastic interactions to mimic the effect of cyclic variation of environmental conditions in the real soils. We find that the amount of deformation per cycle increases if $σ_c$ is approached from below, and it decreases and even vanishes at a novel critical stress $σ_0<σ_c$ when this, in turn, is reached from above. Interestingly, $σ_0$ plays a role similar to the endurance limit in the context of fatigue damage propagation. Despite the model's simplicity, our results offer a fresh perspective on subcritical landform evolution, with implications for the creep of hill slopes over long periods and the precursors to runaway landslides.

cond-mat.dis-nn↗

arXiv2023

The chiral knife edge: a simplified rattleback to illustrate spin inversion

We present the chiral knife edge rattleback, an alternative version of previously presented systems that exhibit spin inversion. We offer a full treatment of the model using qualitative arguments, analytical solutions as well as numerical results. We treat a reduced, one--mode problem which not only contains the essence of the physics of spin inversion, but that also exhibits an unexpected connection to the Chaplygin sleigh, providing new insight into the non-holonomic structure of the problem. We also present exact results for the full problem together with estimates of the time between inversions that agree with previous results in the literature.

physics.pop-ph↗

arXiv2022

The Fate of Shear-Oscillated Amorphous Solids

The behavior of shear-oscillated amorphous materials is studied using a coarse-grained model. Samples are prepared at different degrees of annealing and then subject to athermal and quasistatic oscillatory deformations at various fixed amplitudes. The steady-state reached after several oscillations is fully determined by the initial preparation and the oscillation amplitude, as seen from stroboscopic stress and energy measurements. Under small oscillations, poorly annealed materials display shear-annealing, while ultra-stabilized materials are insensitive to them. Yet, beyond a critical oscillation amplitude, both kind of materials display a discontinuous transition to the same mixed state composed by a fluid shear-band embedded in a marginal solid. Quantitative relations between uniform shear and the steady-state reached with this protocol are established. The transient regime characterizing the growth and the motion of the shear band is also studied.

cond-mat.soft↗

arXiv2021

The yielding of amorphous solids at finite temperatures

We analyze the effect of temperature on the yielding transition of amorphous solids using different coarse-grained model approaches. On one hand we use an elasto-plastic model, with temperature introduced in the form of an Arrhenius activation law over energy barriers. On the other hand, we implement a Hamiltonian model with a relaxational dynamics, where temperature is introduced in the form of a Langevin stochastic force. In both cases, temperature transforms the sharp transition of the athermal case in a smooth crossover. We show that this thermally smoothed transition follows a simple scaling form that can be fully explained using a one-particle system driven in a potential under the combined action of a mechanical and a thermal noise, the stochastically-driven Prandtl-Tomlinson model. Our work harmonizes the results of simple models for amorphous solids with the phenomenological $\sim T^{2/3}$ law proposed by Johnson and Samwer [Phys. Rev. Lett. 95, 195501 (2005)] in the framework of experimental metallic glasses yield observations, and extend it to a generic case. Finally, our results strengthen the interpretation of the yielding transition as an effective mean-field phenomenon.

cond-mat.dis-nn↗

arXiv2020

Properties of the density of shear transformations in driven amorphous solids

The strain load $Δγ$ that triggers consecutive avalanches is a key observable in the slow deformation of amorphous solids. Its temporally averaged value $\langle Δγ\rangle$ displays a non-trivial system-size dependence that constitutes one of the distinguishing features of the yielding transition. Details of this dependence are not yet fully understood. We address this problem by means of theoretical analysis and simulations of elastoplastic models for amorphous solids. An accurate determination of the size dependence of $\langle Δγ\rangle$ leads to a precise evaluation of the steady-state distribution of local distances to instability $x$. We find that the usually assumed form $P(x)\sim x^θ$ (with $θ$ being the so-called pseudo-gap exponent) is not accurate at low $x$ and that in general $P(x)$ tends to a system-size-dependent \textit{finite} limit as $x\to 0$. We work out the consequences of this finite-size dependence standing on exact results for random-walks and disclosing an alternative interpretation of the mechanical noise felt by a reference site. We test our predictions in two- and three-dimensional elastoplastic models, showing the crucial influence of the saturation of $P(x)$ at small $x$ on the size dependence of $\langle Δγ\rangle$ and related scalings.

cond-mat.dis-nn↗

arXiv2012

Fatigue crack propagation in a quasi one-dimensional elasto-plastic model

Fatigue crack advance induced by the application of cyclic quasistatic loads is investigated both numerically and analytically using a lattice spring model. The system has a quasi-one-dimensional geometry, and consists in two symmetrical chains that are pulled apart, thus breaking springs which connect them, and producing the advance of a crack. Quasistatic crack advance occurs as a consequence of the plasticity included in the springs which form the chains, and that implies a history dependent stress-strain curve for each spring. The continuous limit of the model allows a detailed analytical treatment that gives physical insight of the propagation mechanism. This simple model captures key features that cause well known phenomenology in fatigue crack propagation, in particular a Paris-like law of crack advance under cyclic loading, and the overload retardation effect.

cond-mat.mtrl-sci↗