Eran Bouchbinder's blog
https://www.imechanica.org/blog/16914
enDynamic instabilities of frictional sliding at a bimaterial interface
https://www.imechanica.org/node/18531
<div class="field field-name-taxonomy-vocabulary-6 field-type-taxonomy-term-reference field-label-hidden"><div class="field-items"><div class="field-item even"><a href="/taxonomy/term/76">research</a></div></div></div><div class="field field-name-taxonomy-vocabulary-8 field-type-taxonomy-term-reference field-label-hidden"><div class="field-items"><div class="field-item even"><a href="/taxonomy/term/356">friction</a></div><div class="field-item odd"><a href="/taxonomy/term/744">elastodynamics</a></div><div class="field-item even"><a href="/taxonomy/term/5990">instabilities</a></div><div class="field-item odd"><a href="/taxonomy/term/7522">rupture</a></div><div class="field-item even"><a href="/taxonomy/term/2679">Earthquakes</a></div><div class="field-item odd"><a href="/taxonomy/term/1519">tribology</a></div><div class="field-item even"><a href="/taxonomy/term/706">contact mechanics</a></div></div></div><div class="field field-name-body field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"><p>Understanding the dynamic stability of bodies in frictional contact steadily sliding one over the other is of basic interest in various disciplines such as physics, solid mechanics, materials science and geophysics. Here we report on a two-dimensional linear stability analysis of a deformable solid of a finite height H, steadily sliding on top of a rigid solid within a generic rate-and-state friction type constitutive framework, fully accounting for elastodynamic effects.</p>
<p>We derive the linear stability spectrum, quantifying the interplay between stabilization related to the frictional constitutive law and destabilization related both to the elastodynamic bi-material coupling between normal stress variations and interfacial slip, and to finite size effects. The stabilizing effects related to the frictional constitutive law include velocity-strengthening friction (i.e.~an increase in frictional resistance with increasing slip velocity, both instantaneous and under steady-state conditions) and a regularized response to normal stress variations.</p>
<p>We first consider the small wave-number k limit and demonstrate that homogeneous sliding in this case is universally unstable, independently of the details of the friction law. This universal instability is mediated by propagating waveguide-like modes, whose fastest growing mode is characterized by a wave-number satisfying k H ~O(1) and by a growth rate that scales with 1/H. We then consider the limit k H>>1 and derive the stability phase diagram in this case.</p>
<p>We show that the dominant instability mode travels at nearly the dilatational wave-speed in the opposite direction to the sliding direction. In a certain parameter range this instability is manifested through unstable modes at all wave-numbers, yet the frictional response is shown to be mathematically well-posed. Instability modes which travel at nearly the shear wave-speed in the sliding direction also exist in some range of physical parameters. Previous results obtained in the quasi-static regime appear relevant only within a narrow region of the parameter space. Finally, we show that a finite-time regularized response to normal stress variations, within the framework of generalized rate-and-state friction models, tends to promote stability.</p>
<p>The relevance of our results to the rupture of bi-material interfaces is briefly discussed.</p>
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<tr class="odd"><td><span class="file"><img class="file-icon" alt="PDF icon" title="application/pdf" src="/modules/file/icons/application-pdf.png" /> <a href="https://www.imechanica.org/files/LSA_bimaterials_submitted.pdf" type="application/pdf; length=863072">LSA_bimaterials_submitted.pdf</a></span></td><td>842.84 KB</td> </tr>
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</div></div></div>Fri, 03 Jul 2015 06:37:11 +0000Eran Bouchbinder18531 at https://www.imechanica.orghttps://www.imechanica.org/node/18531#commentshttps://www.imechanica.org/crss/node/18531An Eulerian projection method for quasi-static elastoplasticity
https://www.imechanica.org/node/17177
<div class="field field-name-taxonomy-vocabulary-6 field-type-taxonomy-term-reference field-label-hidden"><div class="field-items"><div class="field-item even"><a href="/taxonomy/term/76">research</a></div></div></div><div class="field field-name-taxonomy-vocabulary-8 field-type-taxonomy-term-reference field-label-hidden"><div class="field-items"><div class="field-item even"><a href="/taxonomy/term/169">Plasticity</a></div><div class="field-item odd"><a href="/taxonomy/term/10072">elasto-plasticity</a></div><div class="field-item even"><a href="/taxonomy/term/10073">additive decomposition</a></div><div class="field-item odd"><a href="/taxonomy/term/358">numerical methods</a></div><div class="field-item even"><a href="/taxonomy/term/23">fluid mechanics</a></div></div></div><div class="field field-name-body field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"><p class="MsoPlainText"> <img src="http://imechanica.org/files/proj2.png" alt="" width="500" height="178" /></p>
<p class="MsoPlainText">Hypoelastic-plastic models, which invoke an additive decomposition of the total rate of deformation into elastic and plastic parts, are quite common in various branches of solid mechanics. In the framework of these models, the Eulerian velocity field is usually regarded as the basic field of interest. As the timescale characterizing plastic deformation is typically small compared to elastic wave travel times, and when the loading rates are not very high, quasi-static stress equilibrium is essentially maintained throughout the deformation process. This means that the inertial term involving the time derivative of the velocity field (acceleration) can be omitted from the linear momentum balance equation, which in turn implies that there is no way to explicitly update the velocity field in time. Retaining the inertial term and employing an explicit simulation method would make it prohibitively computationally expensive to consider realistic strain rates, which is physically relevant in many problems.</p>
<p class="MsoPlainText">In the paper attached below (by Chris Rycroft, Yi Sui and Eran Bouchbinder) we address this problem by building a mathematical correspondence between Newtonian fluids in the incompressible limit and hypoelastic-plastic solids in the quasi-static limit. In the incompressible fluids problem, it is the pressure field (rather than the velocity field) that cannot be updated explicitly in time. A well-established numerical approach to solve this problem is Chorin's projection method, whereby the fluid velocity is explicitly updated, and then an elliptic problem for the pressure is solved, which is used to orthogonally project the velocity field to maintain the incompressibility constraint.</p>
<p class="MsoPlainText">Using this correspondence between these two different classes of physical problems, we formulate a new fixed-grid, Eulerian projection method -- analogous to Chorin's projection method for incompressible fluids -- for simulating quasi-static hypoelastic-plastic solids, whereby the stress is explicitly updated, and then an elliptic problem for the velocity is solved, which is used to orthogonally project the stress to maintain the quasi-staticity constraint. We develop a finite-difference implementation of the method and apply it to a specific elasto-viscoplastic model. We demonstrate via a few examples that the method is in quantitative agreement with an explicit method. We also demonstrate that the method can be extended to simulate objects with evolving boundaries.</p>
<p class="MsoPlainText">We find that the numerical method developed here offers a useful practical approach for dealing with hypo-elastoplastic materials in the quasi-static limit. One of the main advantages of the fluid projection method is that it maintains the incompressibility condition through a single algebraic problem for the pressure, which is generally well-conditioned and can be carried out efficiently, and we find that many of the same benefits remain valid for the elasto-plasticity method we develop. Throughout the paper, we find a surprising number of correspondences between the two methods, such as analogous considerations for boundary conditions or the uniqueness of solutions. The mathematical connection opens up interesting possibilities for translating numerical methods for incompressible fluid mechanics over to quasi-static elastoplasticity and vice versa.</p>
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</div></div></div>Tue, 16 Sep 2014 19:43:41 +0000Eran Bouchbinder17177 at https://www.imechanica.orghttps://www.imechanica.org/node/17177#commentshttps://www.imechanica.org/crss/node/17177A new postdoctoral position in the mechanics of glassy/amorphous materials
https://www.imechanica.org/node/12834
<div class="field field-name-taxonomy-vocabulary-6 field-type-taxonomy-term-reference field-label-hidden"><div class="field-items"><div class="field-item even"><a href="/taxonomy/term/73">job</a></div></div></div><div class="field field-name-taxonomy-vocabulary-8 field-type-taxonomy-term-reference field-label-hidden"><div class="field-items"><div class="field-item even"><a href="/taxonomy/term/31">fracture</a></div><div class="field-item odd"><a href="/taxonomy/term/541">job</a></div><div class="field-item even"><a href="/taxonomy/term/549">continuum mechanics</a></div><div class="field-item odd"><a href="/taxonomy/term/871">postdoc</a></div><div class="field-item even"><a href="/taxonomy/term/7746">amorphous materials</a></div><div class="field-item odd"><a href="/taxonomy/term/7747">glasses</a></div><div class="field-item even"><a href="/taxonomy/term/7748">shear banding</a></div><div class="field-item odd"><a href="/taxonomy/term/7749">non-equilibrium thermodynamics</a></div></div></div><div class="field field-name-body field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"><p class="MsoNormal">
<span>A new postdoctoral position in the mechanics of glassy/amorphous materials is<br />
available at the Weizmann Institute of Science. </span><span>The project will focus on<br />
strongly non-linear phenomena such as cavitation, shear-banding and fracture,<br />
with applications to Bulk Metallic Glasses, </span><span>and will involve advanced<br />
theoretical and computational techniques. </span><span>Highly motivated candidates, with a strong<br />
background in theoretical mechanics and/or physics, and experience with<br />
analytical and computational modeling, are encouraged to apply. </span>
</p>
<p class="MsoNormal">
<span>To apply, please send CV, publications list and a statement of research interests<br />
to Dr. Eran Bouchbinder, <a href="mailto:eran.bouchbinder@weizmann.ac.il">eran.bouchbinder@weizmann.ac.il</a></span></p>
</div></div></div>Wed, 25 Jul 2012 10:21:41 +0000Eran Bouchbinder12834 at https://www.imechanica.orghttps://www.imechanica.org/node/12834#commentshttps://www.imechanica.org/crss/node/12834A new postdoc position is available
https://www.imechanica.org/node/9141
<div class="field field-name-taxonomy-vocabulary-6 field-type-taxonomy-term-reference field-label-hidden"><div class="field-items"><div class="field-item even"><a href="/taxonomy/term/73">job</a></div></div></div><div class="field field-name-taxonomy-vocabulary-8 field-type-taxonomy-term-reference field-label-hidden"><div class="field-items"><div class="field-item even"><a href="/taxonomy/term/169">Plasticity</a></div><div class="field-item odd"><a href="/taxonomy/term/356">friction</a></div><div class="field-item even"><a href="/taxonomy/term/439">biomaterials</a></div><div class="field-item odd"><a href="/taxonomy/term/499">dislocations</a></div><div class="field-item even"><a href="/taxonomy/term/549">continuum mechanics</a></div><div class="field-item odd"><a href="/taxonomy/term/685">dynamic fracture</a></div><div class="field-item even"><a href="/taxonomy/term/5681">glass physics</a></div><div class="field-item odd"><a href="/taxonomy/term/5682">nonequilibrium physics</a></div></div></div><div class="field field-name-body field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"><p>A new postdoctoral position in continuum mechanics is available at the Weizmann Institute of Science. Candidates should have a strong background in physics and/or theoretical mechanics, as well as experience with analytical and computational methods for solving partial differential equations. Possible projects include the mechanics of frictional sliding, the mechanics of biomaterials, the mechanics of glassy materials and dislocation-mediated plasticity. Highly motivated candidates are requested to send their CV, publications list and statement of research interests to Dr. Eran Bouchbinder <a href="mailto:eran.bouchbinder@weizmann.ac.il"><strong>eran.bouchbinder@weizmann.ac.il</strong></a></p>
</div></div></div>Thu, 21 Oct 2010 21:06:47 +0000Eran Bouchbinder9141 at https://www.imechanica.orghttps://www.imechanica.org/node/9141#commentshttps://www.imechanica.org/crss/node/9141Postdoctoral/PhD position
https://www.imechanica.org/node/7994
<div class="field field-name-taxonomy-vocabulary-6 field-type-taxonomy-term-reference field-label-hidden"><div class="field-items"><div class="field-item even"><a href="/taxonomy/term/73">job</a></div></div></div><div class="field field-name-body field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"><p>A postdoctoral/PhD position in various non-equilibrium problems in solid mechanics is available at the Weizmann Institute of Science. Candidates should have a strong background in physics and/or theoretical mechanics, as well as experience with analytical and computational methods for solving partial differential equations. More details can be found in <a href="http://www.weizmann.ac.il/chemphys/bouchbinder/">http://www.weizmann.ac.il/chemphys/bouchbinder/</a> For information about specific research projects, please send CV, a publications list and a statement of research interests to Dr. Eran Bouchbinder, <a href="mailto:eran.bouchbinder@weizmann.ac.il">eran.bouchbinder@weizmann.ac.il</a> (PhD candidates must have a Master of Science (MSc) degree)</p>
</div></div></div>Thu, 15 Apr 2010 08:38:14 +0000Eran Bouchbinder7994 at https://www.imechanica.orghttps://www.imechanica.org/node/7994#commentshttps://www.imechanica.org/crss/node/7994Weakly Nonlinear Theory of Dynamic Fracture
https://www.imechanica.org/node/7827
<div class="field field-name-taxonomy-vocabulary-6 field-type-taxonomy-term-reference field-label-hidden"><div class="field-items"><div class="field-item even"><a href="/taxonomy/term/76">research</a></div></div></div><div class="field field-name-taxonomy-vocabulary-8 field-type-taxonomy-term-reference field-label-hidden"><div class="field-items"><div class="field-item even"><a href="/taxonomy/term/86">singularity</a></div><div class="field-item odd"><a href="/taxonomy/term/185">experimental mechanics</a></div><div class="field-item even"><a href="/taxonomy/term/481">Nonlinear elasticity</a></div><div class="field-item odd"><a href="/taxonomy/term/505">asymptotic methods</a></div><div class="field-item even"><a href="/taxonomy/term/685">dynamic fracture</a></div><div class="field-item odd"><a href="/taxonomy/term/810">finite deformation</a></div><div class="field-item even"><a href="/taxonomy/term/995">instability</a></div><div class="field-item odd"><a href="/taxonomy/term/2801">crack tip</a></div></div></div><div class="field field-name-body field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"><p class="MsoNormal">
A fundamental understanding of the dynamics of brittle fracture remains a challenge of great importance for various scientific disciplines. From a theoretical point of view, a major difficulty in making progress in this problem stems from the fact that it intrinsically involves the coupling between widely separated time and length scales. Brittle fracture is ultimately driven by the release of linear elastic energy stored on large scales, while this energy is being dissipated in the very small scales near the front of a crack, where large stresses and deformations are concentrated and material separation is actually taking place. The strongly nonlinear and dissipative dynamics in the near vicinity of a crack's front controls the rate of crack growth and its direction, and hence its resolution seems relevant. Indeed, there are indications that various fast fracture instabilities (micro-branching, oscillations) are intimately related to the small scale physics near a crack's front. On the other hand, the phenomenology of brittle fracture appears to be rather universal, being qualitatively and quantitatively similar in materials with wholly different micro-structures and dissipative mechanisms (e.g. glassy polymers, structural glasses and elastomer gels).
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These observations may suggest that a well-established theory of brittle fracture should incorporate a lengthscale that is associated with the near crack front region, but should otherwise be independent of the details of the small scales physics (unless one aims at calculating the fracture energy, i.e. the amount of energy needed to propagate a crack, instead of using it an a phenomenological material parameter). The canonical theory of fracture, linear elastic fracture mechanics (LEFM), is a scale-free theory and hence every lengthscale that appears in this framework is necessarily of a geometrical nature. This immediately implies that the identification of a non-geometric lengthscale entails the extension of LEFM when it breaks down near the front of a crack. As LEFM is based on a linear elastic constitutive behavior, which is only a first term in a more general displacement-gradients expansion, it is expected to break down near the front of a crack, where deformations become large enough to invalidate the linearity assumption. Progress in understanding the physics of this critical, near-front, nonlinear region has been, on the whole, limited by our lack of hard data describing the detailed physical processes that occur within. Due to the microscopic size and near–sound speed propagation of this region, it is generally experimentally intractable.
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<p> </p>
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Recently, this experimental barrier was overcome by using a quasi-2D brittle neo-Hookean material (polyacrylamide<span> </span>gel) in which the fracture phenomenology mirrors that of more standard brittle amorphous materials (e.g. soda-lime glass and Plexiglass), but in which the near-tip (a crack-front becomes a crack-tip in 2D) region is significantly larger and moves significantly more slowly [1, 4]. The latter property allows unprecedented, direct and precise measurements of the near-tip fields of rapid cracks. These experiments revealed in detail how the canonical 1/√r fields and parabolic crack tip opening displacement (CTOD) of LEFM break down as the tip is approached.
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<p> </p>
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To account for these observations, a weakly nonlinear theory of dynamic fracture was developed based on a systematic displacement-gradients expansion [2, 3]. The theory predicts novel, universal, 1/r singular displacement-gradients and log(r) displacements. It was shown to be in excellent quantitative agreement with the direct near-tip measurements of rapid cracks [2, 3]. The theory also resolves various puzzles in LEFM, such as the fact that the normal (to the crack propagation direction) component of the linear strain tensor ahead of a running crack becomes negative at sufficiently high speeds, which is physically unintuitive [2]. <span> </span>The presence of linear and weakly nonlinear terms in the crack tip solution allows the definition of a new lengthscale (basically by taking the ratio of these terms), that is shown to be related to a high-speed crack tip oscillatory instability [5]. This lengthscale may hold the key for unlocking various open questions in dynamic fracture. The special mathematical properties of the 1/r singularity (which is strictly forbidden in LEFM) and its relation to the concept of autonomy are discussed in detail in [3]. It is important to note that the weakly nonlinear theory is universally applicable since elastic nonlinearities must precede any irreversible behavior as the crack tip is approached.
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<p> </p>
<p class="MsoNormal">
A very recent combined experimental and theoretical study of the large deformation crack-tip region in a neo-Hookean brittle material revealed a hierarchy of linear and nonlinear elastic zones through which energy is transported before being dissipated at a crack’s tip [4]. This result provides a comprehensive picture of how remotely applied forces drive brittle failure and highlight the emergence of a lengthscale associated with nonlinear elastic effects, which are expected to precede near-tip dissipation. The results are corroborated by unprecedented direct measurements of the linear and nonlinear J-integral for cracks approaching the Rayleigh wave speed.<span> </span>
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<p> </p>
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It is important to stress that LEFM works perfectly well for the gels used in the experiments where it should - not too close to the tip. In fact, these experiments provide the most comprehensive validation of LEFM under fully dynamic conditions, as this material has successfully “passed” every “test” that LEFM can throw its way (e.g. functional form of fields not too close to the tip, equations of motions in both an infinite medium and strip – soon to be published in Physical Review Letters); therefore, these results can be considered to be much more general than simply relevant for this class of neo-Hookean materials. Finally, these experiments have also demonstrated that – at least in this class of materials – nonlinear effects entirely dominate the behavior of the fields surrounding the crack’s tip. Dissipation may still be considered “point-like” – but this material shows that the two qualitatively different mechanisms for the breakdown of LEFM (nonlinear elasticity and dissipation) are separated. It remains to be seen if this is also characteristic for other materials. Currently, these materials are the only ones for which we have such detailed data.
</p>
<p class="MsoNormal">
</p>
<p class="MsoNormal">
[1] A. Livne, E. Bouchbinder, J. Fineberg,
</p>
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<span> </span><strong>Breakdown of Linear Elastic Fracture Mechanics near the Tip </strong>
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<strong> of a Rapid Crack</strong>,
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<a href="http://link.aps.org/doi/10.1103/PhysRevLett.101.264301" target="_blank">Phys. </a><a href="http://link.aps.org/doi/10.1103/PhysRevLett.101.264301" target="_blank">Rev. Lett. 101, 264301 (2008).</a>
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Also: <span> </span><a href="http://arxiv.org/abs/0807.4866" target="_blank">ArXiv:0807.4866</a>
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[2] A. Livne, E. Bouchbinder, J. Fineberg, <strong>Weakly Nonlinear Theory </strong>
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<p class="MsoNormal">
<strong> of Dynamic Frcature</strong><br /><span> </span><a href="http://link.aps.org/doi/10.1103/PhysRevLett.101.264302" target="_blank">Phys. Rev. Lett. 101, 264302 (2008).</a>
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Also: <a href="http://arxiv.org/abs/0807.4868" target="_blank">ArXiv:0807.4868</a>
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[3] E. Bouchbinder, A. Livne, J. Fineberg, <br /><span> </span><span> </span><strong>The 1/r Singularity in Weakly Nonlinear Fracture Mechanics</strong> <br /><span> </span><a href="http://dx.doi.org/10.1016/j.jmps.2009.05.006" target="_blank">J. Mech. Phys. Solids 57, 1568 (2009).</a>
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Also: <a href="http://arxiv.org/abs/0902.2121" target="_blank">ArXiv:0902.2121</a>
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[4] A. Livne, E. Bouchbinder, I. Svetlizky, J. Fineberg,
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<span> </span><strong>The Near-Tip Fields of Fast Cracks<br /></strong><span> </span><a href="http://www.sciencemag.org/cgi/content/abstract/327/5971/1359" target="_blank">Science 327, 1359 (2010).</a>
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[5]<span> </span>E. Bouchbinder
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<span> </span><strong>Dynamic Crack Tip Equation of Motion: High-speed </strong>
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<strong> Oscillatory Instability</strong>
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<a href="http://link.aps.org/doi/10.1103/PhysRevLett.103.164301" target="_blank">Phys. Rev. Lett. 103, 164301 (2009).</a>
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Also: <a href="http://arxiv.org/abs/0908.1178" target="_blank">ArXiv:0908.1178</a>
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<p> </p>
</div></div></div>Wed, 17 Mar 2010 15:40:11 +0000Eran Bouchbinder7827 at https://www.imechanica.orghttps://www.imechanica.org/node/7827#commentshttps://www.imechanica.org/crss/node/7827Nonequilibrium Thermodynamics in Solid Mechanics
https://www.imechanica.org/node/7512
<div class="field field-name-taxonomy-vocabulary-6 field-type-taxonomy-term-reference field-label-hidden"><div class="field-items"><div class="field-item even"><a href="/taxonomy/term/76">research</a></div></div></div><div class="field field-name-taxonomy-vocabulary-8 field-type-taxonomy-term-reference field-label-hidden"><div class="field-items"><div class="field-item even"><a href="/taxonomy/term/169">Plasticity</a></div><div class="field-item odd"><a href="/taxonomy/term/180">thermodynamics</a></div><div class="field-item even"><a href="/taxonomy/term/499">dislocations</a></div><div class="field-item odd"><a href="/taxonomy/term/861">glass</a></div><div class="field-item even"><a href="/taxonomy/term/1268">deformation</a></div><div class="field-item odd"><a href="/taxonomy/term/1398">continuum thermomechanics</a></div><div class="field-item even"><a href="/taxonomy/term/2622">nonequilibrium</a></div></div></div><div class="field field-name-body field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"><p>
Solids that are driven beyond their elastic limit exhibit strongly disspative and irreversible dynamical behaviors. Such behaviors call for the development of nonequilibrium approaches that go beyond standard equilibrium thermodynamics. In a recent work we have developed an internal-variable, effective-temperature non-equilibrium thermodynamics for glass-forming and polycrystalline materials driven away from thermodynamic equilibrium by external forces [1, 2]. The basic idea is that the slow configurational (structural) degrees of freedom of such materials are weakly coupled to the fast kinetic-vibrational degrees of freedom and therefore these two subsystems can be described by different temperatures during deformation. The configurational subsystem is defined by the mechanically stable positions of the constituent atoms, i.e. the "inherent structures", and is characterized by an effective temperature. The kinetic-vibrational subsystem is defined by the momenta and the displacements of the atoms at small distances away from their stable positions, and is characterized by the bath temperature.
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In glass-forming materials, the configurational degrees of freedom include structural objects such as Shear-Transformation-Zones (STZ) and vacancy-like defects. In polycrystalline materials, the configurational degrees of freedom include structural defects such as interstitials, dislocations, disclinations, stacking faults and grain boundaries. A continuum level description of the configurational subsystem contains coarse-grained internal variables that are state variables that account for the effect of the evolving structure on various macroscopic mechanical properties. We highlighted the need for understanding how both energy and entropy are shared by the different components of the system and used the first and second laws of thermodynamics to constrain the equations of motion for the internal variables and the effective temperature.
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The proposed framework should be supplemented with physics-based models for describing specific phenomena and systems. It was recently applied to three different problems:
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A. Plastic deformation of amorphous materials [3].
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The theory was based on the Shear-Transformation-Zones (STZ) model, which was already shown to be in agreement with a wide range of amorphous plasticity phenomena, including shear banding instabilities.
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B. Dislocation-mediated plasticity and strain-hardening of polycrystalline materials [4].
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The theory was shown to be in agreement with experimental strain-hardening data for Cu over a wide range of temperatures and strain rates. Furthermore, the transition between stage II and stage III hardening, including the observation that this transition occurs at smaller strains for higher temperatures, was predicted. Finally, power-law rate hardening in the strong-shock regime was explained.
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C. A thermo-mechanical memory effect in glassy polymers [5].
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The memory effect, the so-called "Kovacs effect", reveals some of the most subtle and important nonequilibrium features of glassy materials in which they deform irreversibly and remember their thermo-mechanical histories. The developed theory was shown to be in good quantitative agreement with extensive molecular dynamics simulations of ortho-terphenyl (OTP).
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[1] E. Bouchbinder and J.S. Langer,<strong> Nonequilibrium Thermodynamics of Driven Amorphous Materials I </strong><strong>:</strong><strong> Internal Degrees of Freedom and Volume Deformation</strong>, <a href="http://link.aps.org/doi/10.1103/PhysRevE.80.031131">Phys. Rev. E 80, 031131 (2009)</a>.
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[2] E. Bouchbinder and J.S. Langer,<strong> Nonequilibrium Thermodynamics of Driven Amorphous Materials II </strong><strong>: Effective-Temperature Theory</strong>, <a href="http://link.aps.org/doi/10.1103/PhysRevE.80.031132">Phys. Rev. E 80, 031132 (2009)</a>.
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[3] E. Bouchbinder and J.S. Langer,<strong> Nonequilibrium Thermodynamics of Driven Amorphous Materials III </strong><strong>: Shear-Transformation-Zone Plasticity</strong>, <a href="http://link.aps.org/doi/10.1103/PhysRevE.80.031133">Phys. Rev. E 80, 031133 (2009)</a>.
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[4] J.S. Langer, E. Bouchbinder and T. Lookman,<strong> Thermodynamic Theory of Dislocation-mediated Plasticity</strong>,<strong> </strong><a href="http://arxiv.org/abs/0908.3913">arXiv:0908.3913 (2009)</a>.
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[5] E. Bouchbinder and J.S. Langer, <strong>Nonequilibrium Thermodynamics of the Kovacs Effect</strong>, <a href="http://arxiv.org/abs/1001.3701">arXiv:1001.3701 (2010)</a>.
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</div></div></div>Wed, 03 Feb 2010 12:44:36 +0000Eran Bouchbinder7512 at https://www.imechanica.orghttps://www.imechanica.org/node/7512#commentshttps://www.imechanica.org/crss/node/7512