BARÉS Jonathan
Fonction : Ingénieur de Recherche
jonathan.bares
umontpellier.fr
0467149663
Bureau: B6.5, Etg: 1, Bât: Halle  Site : SaintPriest
Programme de Recherche/CV:  
Domaines de Recherche:  Sciences de l'ingénieur/Acoustique
 Sciences de l'ingénieur/Matériaux
 Sciences de l'ingénieur/Mécanique/Mécanique des solides
 Sciences de l'ingénieur/Mécanique
 Sciences de l'ingénieur/Traitement du signal et de l'image
 Sciences de l'ingénieur/Mécanique/Mécanique des matériaux
 Physique/Physique/Physique Classique
 Physique/Physique/Analyse de données, Statistiques et Probabilités
 Sciences de l'ingénieur/Mécanique/Biomécanique
 Sciences du Vivant/Biologie végétale
 Physique/Matière Condensée/Mécanique statistique
 Physique/Matière Condensée/Systèmes désordonnés et réseaux de neurones
 Physique/Matière Condensée/Science des matériaux

Dernieres productions scientifiques :


Crack growth in heterogeneous brittle solids: intermittency, crackling and induced seismicity
Auteur(s): Barés J., Bonamy Daniel
(Article) Publié:
Philosophical Transactions Of The Royal Society A Mathematical, Physical And Engineering Sciences, vol. p. (2018)
Ref HAL: hal01908906_v1
DOI: 10.1098/rsta.2017.0386
Exporter : BibTex  endNote
Résumé: Crack growth is the basic mechanism leading to the failure of brittle materials. Engineering addresses this problem within the framework of continuum mechanics, which links deterministically the crack motion to the applied loading. Such an idealization, however, fails in several situations and in particular cannot capture the highly erratic (earthquakelike) dynamics sometimes observed in slowly fracturing heterogeneous solids. Here, we examine this problem by means of innovative experiments of crack growth in artificial rocks of controlled microstructure. The dynamical events are analysed at both global and local scales, from the time fluctuation of the spatially averaged crack speed and the induced acoustic emission, respectively. Their statistics are characterized and compared with the predictions of a recent approach mapping fracture onset with the depinning of an elastic interface. Finally, the overall timesize organization of the events are characterized to shed light on the mechanisms underlying the scaling laws observed in seismology.




Sinking in a bed of grains activated by shearing
Auteur(s): Zheng Hu, Wang Dong, Barés J., Behringer Robert
(Article) Publié:
Physical Review E, vol. 98 p. (2018)
Ref HAL: hal01878501_v1
DOI: 10.1103/PhysRevE.98.010901
Exporter : BibTex  endNote
1 citation
Résumé: We show how a weak force f enables intruder motion through dense granular materials subject to external mechanical excitations, in the present case, stepwise shearing. A force acts on a Teflon disk in a twodimensional system of photoelastic disks. This force is much smaller than the smallest force needed to move the disk without any external excitation. In a cycle, the material plus intruder are sheared quasistatically from γ=0 to γmax, and then backwards to γ=0. During various cycle phases, fragile and jammed states form. Net intruder motion δ occurs during fragile periods generated by shear reversals. δ per cycle, e.g., the quasistatic rate c, is constant, linearly dependent on γmax and f. It vanishes as c∝(ϕc−ϕ)a, with a≃3 and ϕc≃ϕJ, reflecting the stiffening of granular systems under shear [J. Ren, J. A. Dijksman, and R. P. Behringer, Phys. Rev. Lett. 110, 018302 (2013)] as ϕ→ϕJ. The intruder motion induces largescale grain circulation. In the intruder frame, this motion is a granular analog to fluid flow past a cylinder, where f is the drag force exerted by the flow.




Aftershock sequences and seismiclike organization of acoustic events produced by a single propagating crack
Auteur(s): Barés J., Dubois Alizée, Hattali Lamine, Dalmas Davy, Bonamy Daniel
(Article) Publié:
Nature Communications, vol. 9 p.1253 (2018)
Ref HAL: hal01756904_v1
DOI: 10.1038/s41467018035594
Exporter : BibTex  endNote
Résumé: Brittle fractures of inhomogeneous materials like rocks, concrete, or ceramics are of two types: Nominally brittle and driven by the propagation of a single dominant crack or quasibrittle and resulting from the accumulation of many microcracks. The latter goes along with acoustic noise, whose analysis has revealed that events form aftershock sequences obeying characteristic laws reminiscent of those in seismology. Yet, their origin lacks explanation. Here we show that such a statistical organization is not only specific to the multicracking situations of quasibrittle failure and seismology, but also rules the acoustic events produced by a propagating crack. This simpler situation has permitted us to relate these laws to the overall scalefree distribution of interevent time and energy and to uncover their selection by the crack speed. These results provide a comprehensive picture of how acoustic events are organized upon material failure in the most fundamental of fracture states: single propagating cracks.




Force and Mass Dynamics in NonNewtonian Suspensions
Auteur(s): Lim Melody, Barés J., Zheng Hu, Behringer Robert P.
(Article) Publié:
Physical Review Letters, vol. 119 p.184501 (2017)
Ref HAL: hal01669033_v1
DOI: 10.1103/PhysRevLett.119.184501
Exporter : BibTex  endNote
Résumé: Above a certain solid fraction, dense granular suspensions in water exhibit nonNewtonian behavior,including impactactivated solidification. Although it has been suggested that solidification depends onboundary interactions, quantitative experiments on the boundary forces have not been reported. Usinghighspeed video, tracer particles, and photoelastic boundaries, we determine the impactor kinematics andthe magnitude and timings of impactordriven events in the body and at the boundaries of cornstarchsuspensions. We observe mass shocks in the suspension during impact. The shock front dynamics arestrongly correlated to those of the intruder. However, the total momentum associated with this shock neverapproaches the initial impactor momentum. We also observe a faster second front associated with thepropagation of pressure to the boundaries of the suspension. The two fronts depend differently on the initialimpactor speed v0 and the suspension packing fraction. The speed of the pressure wave is at least an orderof magnitude smaller than (linear) ultrasound speeds obtained for much higher frequencies, pointing tocomplex amplitude and frequency response of cornstarch suspensions to compressive strains.




Local and global avalanches in a 2D sheared granular medium
Auteur(s): Barés J., Wang Dengming, Wang Dong, Bertrand Thibault, O 'hern Corey, Behringer Robert
(Article) Publié:
Physical Review E, vol. 96 p.052902 (2017)
Ref HAL: hal01650149_v1
DOI: 10.1103/PhysRevE.96.052902
Exporter : BibTex  endNote
3 citations
Résumé: We present the experimental and numerical studies of a 2D sheared amorphous material constituted of bidisperse photoelastic disks. We analyze the statistics of avalanches during shear including the local and global fluctuations in energy and changes in particle positions and orientations. We find scale free distributions for these global and local avalanches denoted by powerlaws whose cutoffs vary with interparticle friction and packing fraction. Different exponents are found for these powerlaws depending on the quantity from which variations are extracted. An asymmetry in time of the avalanche shapes is evidenced along with the fact that avalanches are mainly triggered from the shear bands. A simple relation independent from the intensity, is found between the number of local avalanches and the global avalanches they form. We also compare these experimental and numerical results for both local and global fluctuations to predictions from meanfield and depinning theories.


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