Xiaoding Wei's blog
https://imechanica.org/blog/2280
enA new continuum model for metallic glass based on thermodynamics
https://imechanica.org/node/24719
<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-body field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"><p><span>My group at Peking University proposed a novel mechano-chemical continuum model based on the framework of thermodynamics that can describe the microstructural evolution in metallic glass, and connect it with the macroscopic plastic deformation. The model successfully simulated the shear band instability and dilatancy effects of metallic glass under uniaxial tension and simple shear. Furthermore, the model discovers that the transition of the creep behavior of metallic glass under low and high-stress levels is associated with two different atomic diffusion mechanisms that driven by thermal energy gradient and strain energy gradient, respectively (Figure 1). At low stresses, the creep is accompanied by atom flows along the concentration gradient, and the material tends to be more uniform; while at high stresses, the creep is accompanied by atom flows along the strain energy gradient, and the structural heterogeneity gradually strengthens until the material becomes unstable. The new continuum constitutive theory helps the understanding of the relationship between the microstructure and macroscopic properties in metallic glass and other amorphous systems. This work has been published in <em>Journal of the Mechanics and Physics of Solids </em>(<a href="https://doi.org/10.1016/j.jmps.2020.104216">https://doi.org/10.1016/j.jmps.2020.104216</a>). </span></p>
<p><span><img src="https://imechanica.org/files/metallic%20glass.jpg" alt="" width="397" height="357" /></span></p>
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<p class="MsoNormal"><span><span>Figure 1. Top: different atomic kinetics during the creep of metallic glasses. At low stresses, atoms move from large-free-volume (loose) regions to small-free-volume (dense) regions. At high stresses, however, atoms move from the loose regions to the dense regions. Bottom: Nucleation and formation of a major shear band in metallic glass under uniaxial tension.</span></span></p>
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</div></div></div>Wed, 11 Nov 2020 13:50:00 +0000Xiaoding Wei24719 at https://imechanica.orghttps://imechanica.org/node/24719#commentshttps://imechanica.org/crss/node/24719Postdoc openings at Peking University
https://imechanica.org/node/24573
<div class="field field-name-body field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"><p><span>Prof. Xiaoding Wei's group at the Department of Mechanics and Engineering Science at Peking University (Group Website: <a href="https://www.nml-pku.com/" target="_blank" rel="noopener noreferrer">https://www.nml-pku.com/</a>) has postdoc openings for graduates with Ph.D. degrees in Applied Physics, Chemical Engineering, Materials Science, and Mechanical Engineering:</span></p>
<p><span>Research Area #1: Multiscale modeling and simulations: experiences in simulations of material systems including 1D or 2D materials, fiber-reinforced composites, nanocrystalline metals, metallic glass, polymers, and so on. using FEM, coarse-grained simulations, Molecular Dynamics, and Density Functional Theory.</span></p>
<p><span></span><span>Research Area #2: Material synthesis and nanomechanical characterization: experiences in synthesis or characterization of mechanical properties of material systems including 1D or 2D materials, nanocrystalline metallic films, metallic glass, fiber-reinforced composites, etc. </span></p>
<p><span>Please contact Prof. Wei at <a href="mailto:xd-wei@outlook.com">xd-wei@outlook.com</a> </span></p>
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</div></div></div>Mon, 07 Sep 2020 01:27:31 +0000Xiaoding Wei24573 at https://imechanica.orghttps://imechanica.org/node/24573#commentshttps://imechanica.org/crss/node/24573Multiple Postdoc Positions available in Nanomechanics Lab at Peking University
https://imechanica.org/node/22450
<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 align="left"><strong>Department of Mechanics and Engineering Science at Peking University </strong>has postdoc openings for graduates with Ph.D. degrees in Applied Physics, Chemical Engineering, Materials Science, and Mechanical Engineering:</p>
<p align="left"><strong>Research Area #1 Multiscale modeling and simulations:</strong> experiences in simulations of material systems including 1D or 2D materials, fiber-reinforced composites, nanocrystalline metals, metallic glass, polymers and so on. using FEM, coarse-grained simulations, Molecular Dynamics, and Density Functional Theory.</p>
<p align="left"><strong>Research Area #2 Material synthesis and nanomechanical characterization: </strong>experiences in synthesis or characterization of mechanical properties of material systems including 1D or 2D materials, nanocrystalline metallic films, metallic glass, fiber-reinforced composites, etc. </p>
<p align="left"> </p>
<p align="left">Please send your applications materials (including CV, representative publications, contact information of at least three references) to Prof. Xiaoding Wei at <a href="mailto:xd-wei@outlook.com">xd-wei@outlook.com</a></p>
</div></div></div>Thu, 21 Jun 2018 13:13:07 +0000Xiaoding Wei22450 at https://imechanica.orghttps://imechanica.org/node/22450#commentshttps://imechanica.org/crss/node/22450Call for abstracts USNC/TAM 2018 Symposium 321: Mechanics in Nano- And Micro-Scale Material Design: Synthesis, Experiments, Theory and Simulation
https://imechanica.org/node/21851
<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 lang="EN-US" xml:lang="EN-US">Dear Colleagues,</span></p>
<p class="MsoNormal"><span lang="EN-US" xml:lang="EN-US">The 18th USNC/TAM Congress to be held June 5-9, 2018 in Chicago. We would like to invite you to submit an abstract to a symposium named </span><strong><span lang="EN-US" xml:lang="EN-US">321: Mechanics in Nano- And Micro-Scale Material Design: Synthesis, Experiments, Theory and Simulation.</span></strong></p>
<p class="MsoNormal"><span lang="EN-US" xml:lang="EN-US">This symposium addresses recent advances in fundamental mechanics related to nano- and micro-scale material development, synthesis, experimental characterization, theory and modeling. Topics of interest (but not limited to) include: 1). Multi-scale mechanics of engineered, biological, and multi-functional materials 2). Synthesis of materials with nano- or micro-scale structures, or hierarchical composites consist of multi-scale structures. 3). Multi-scale experimentation design and characterization of constitutive laws of nano- and micro-scale materials to reveal the structure-property relationships. 4). Theory, simulation and modeling of nano- and micro-scale materials or composites with multilevel hierarchy. </span></p>
<p class="MsoNormal"><span lang="EN-US" xml:lang="EN-US">Abstracts are due by Nov. 25, 2018 via the website:</span></p>
<p class="MsoNormal"><span lang="EN-US" xml:lang="EN-US"><a href="http://sites.northwestern.edu/usnctam2018/usnctam-2018/abstract-submission/">http://sites.northwestern.edu/usnctam2018/usnctam-2018/abstract-submission/</a></span></p>
<p class="MsoNormal"><span>We look forward to seeing you in Chicago in 2018!</span></p>
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<p class="MsoNormal"><span lang="EN-US" xml:lang="EN-US"> </span></p>
</div></div></div>Wed, 15 Nov 2017 01:57:04 +0000Xiaoding Wei21851 at https://imechanica.orghttps://imechanica.org/node/21851#commentshttps://imechanica.org/crss/node/21851"Imperfection" in graphene oxide invites surprising properties in a mechano-chemical way
https://imechanica.org/node/18756
<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/10717">graphene oxide</a></div><div class="field-item odd"><a href="/taxonomy/term/169">Plasticity</a></div><div class="field-item even"><a href="/taxonomy/term/25">ductility</a></div><div class="field-item odd"><a href="/taxonomy/term/3280">defects</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>In an article published in the August 20 issue of <em>Nature Communications, </em>we report a mechanochemical phenomenon in graphene oxide membranes, covalent epoxide-to-ether functional group transformations that deviate from epoxide ring-opening reactions, discovered through nanomechanical experiments and density functional-based tight binding calculations.</p>
<p>As an oxidized derivative of graphene, graphene oxide comprises two carbon atoms and one oxygen atom, a formation known as an epoxide. This can be imagined as a triangle with two carbon atoms at the base and an oxygen atom on top. When an epoxide's bonds are chemically broken, the carbon-oxygen bonds break, leaving the carbon-carbon bond in tact. We, however, found that when an in-plane tension was applied to graphene oxide, the carbon-carbon bond broke first, leaving the carbon-oxygen bonds in place. These mechanochemical transformations in a two-dimensional system are directionally dependent, and confer pronounced plasticity and damage tolerance to graphene oxide monolayers. Additional experiments on chemically modified graphene oxide membranes, with ring-opened epoxide groups, verify this unique deformation mechanism. These studies establish graphene oxide as a two-dimensional building block with highly tuneable mechanical properties for the design of high-performance nanocomposites, and stimulate the discovery of new bond-selective chemical transformations in two-dimensional materials.</p>
<p>link to the article: <a class="links" title="link to the article" href="http://www.nature.com/ncomms/2015/150820/ncomms9029/full/ncomms9029.html" target="_blank">http://www.nature.com/ncomms/2015/150820/ncomms9029/full/ncomms9029.html</a></p>
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</div></div></div>Tue, 25 Aug 2015 03:10:14 +0000Xiaoding Wei18756 at https://imechanica.orghttps://imechanica.org/node/18756#commentshttps://imechanica.org/crss/node/18756Deadline Extended! IMECE 2013 Symposium on Advanced Nanomanufacturing and Mechanics of Structural Nanomaterials (Topic 10-7)
https://imechanica.org/node/14124
<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/74">conference</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/8409">conference | nanomaterials | nanomanufacturing | nanomechanics | biomimetic | bioinspired</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>Dear Colleagues, <br />
On behalf of the co-organizers, I would like to invite you to submit an abstract to the symposium on "<strong>Symposium on Advanced Nanomanufacturing and Mechanics of Structural Nanomaterials</strong>", Topic <strong>10-7</strong> under track "<strong>Mechanics of Solids, Structures and Fluids</strong>" at the upcoming 2013 ASME IMECE conference to be held in San Diego, CA from November 15-21.<br />
This symposium will review the state-of-the-art on nanomanufacturing and mechanical performance of advanced nanoreinforced and/or nanostructured fibers, composites, and ther high-performance materials with special emphasis on the mechanisms governing their deformation and failure. Experimental and modeling aspects will be covered. Biomimetic and bioinspired materials will be reviewed. Issues to be resolved to further improve materials processing and performance will be identified and discussed. <br />
Interested authors should submit their abstracts via the website <a href="http://www.asmeconferences.org/Congress2013/Author/NewAbstract.cfm">http://www.asmeconferences.org/Congress2013/Author/NewAbstract.cfm</a> by <strong>February 14, 2013</strong>. <br />
Please feel free to forward this to other interested parties. <br />
We look forward to seeing you in San Diego!</p>
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Sincerely,
</p>
<p>
Xiaoding Wei
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Department of Mechanical Engineering<br />
Northwestern Uniersity<br />
2145 Sheridan Road, Evanston IL 60208
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On behalf of: <br />
Yuris A. Dzenis, Ph.D. <br />
R. Vernon McBroom Professor of Engineering<br />
Department of Mechanical and Materials Engineering <br />
University of Nebraska-Lincoln, Lincoln NE 68588-0526
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<p>
Horacio D. Espinosa<br />
James and Nancy Farley Professor of Mechanical Engineering<br />
Director, Theoretical and Applied Mechanics Program<br />
McCormick School of Engineering<br />
Northwestern University
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</div></div></div>Sat, 02 Feb 2013 18:09:29 +0000Xiaoding Wei14124 at https://imechanica.orghttps://imechanica.org/node/14124#commentshttps://imechanica.org/crss/node/14124Error | iMechanica