iMechanica - Comments for "Woven Nano-Structure of Carbon Nanotubes"
https://imechanica.org/node/1022
Comments for "Woven Nano-Structure of Carbon Nanotubes"enballistic-resistance applications
https://imechanica.org/comment/1961#comment-1961
<a id="comment-1961"></a>
<p><em>In reply to <a href="https://imechanica.org/node/1022">Woven Nano-Structure of Carbon Nanotubes</a></em></p>
<div class="field field-name-comment-body field-type-text-long field-label-hidden"><div class="field-items"><div class="field-item even"><p>Bin: </p>
<p>You have mentioned that the woven nano-structure of carbon nanotubes can be designed for ballistic-resistance applications.</p>
<p>What's your view on this?</p>
<p>Maybe someday we can design a composite material reinforced by these woven nanotubes, which could be a very strong material but still light enough for carrying.</p>
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</ul>Mon, 26 Mar 2007 14:47:47 +0000Henry Tancomment 1961 at https://imechanica.orgHenry, so far we have not
https://imechanica.org/comment/1939#comment-1939
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<p><em>In reply to <a href="https://imechanica.org/comment/1912#comment-1912">dislocations generated from the nano-indenter tip</a></em></p>
<div class="field field-name-comment-body field-type-text-long field-label-hidden"><div class="field-items"><div class="field-item even"><p class="MsoNormal"><span>Henry, so far we have not studied deformation induced dislocations. They will be our research subjects later.</span></p>
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</ul>Sat, 24 Mar 2007 23:33:24 +0000Bin Liucomment 1939 at https://imechanica.orgdislocations generated from the nano-indenter tip
https://imechanica.org/comment/1912#comment-1912
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<p><em>In reply to <a href="https://imechanica.org/comment/1909#comment-1909">Sure, AFEM can be used in</a></em></p>
<div class="field field-name-comment-body field-type-text-long field-label-hidden"><div class="field-items"><div class="field-item even"><p>In your nanoindentation simulation (Phy. Rev. 2005), did you see dislocations generated ffrom the indenter tip?</p>
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</ul>Sat, 24 Mar 2007 02:47:33 +0000Henry Tancomment 1912 at https://imechanica.orgSure, AFEM can be used in
https://imechanica.org/comment/1909#comment-1909
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<p><em>In reply to <a href="https://imechanica.org/comment/1907#comment-1907">dynamic problems</a></em></p>
<div class="field field-name-comment-body field-type-text-long field-label-hidden"><div class="field-items"><div class="field-item even"><p>Sure, AFEM can be used in dynamics simulation. Since we already know how to compute the stiffness matrix and the mass matrix is easily abtained, the AFEM dynamics simulation is the similar to traditional FEM.</p>
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</ul>Sat, 24 Mar 2007 00:47:38 +0000Bin Liucomment 1909 at https://imechanica.orgdynamic problems
https://imechanica.org/comment/1907#comment-1907
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<p><em>In reply to <a href="https://imechanica.org/comment/1906#comment-1906">Dear Yinglee,
Thanks for</a></em></p>
<div class="field field-name-comment-body field-type-text-long field-label-hidden"><div class="field-items"><div class="field-item even"><p>Bin, can this method be easily applied to dynamic problems?</p>
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</ul>Sat, 24 Mar 2007 00:07:20 +0000Henry Tancomment 1907 at https://imechanica.orgDear Yinglee,
Thanks for
https://imechanica.org/comment/1906#comment-1906
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<p><em>In reply to <a href="https://imechanica.org/comment/1871#comment-1871">Intresting:)</a></em></p>
<div class="field field-name-comment-body field-type-text-long field-label-hidden"><div class="field-items"><div class="field-item even"><p class="MsoNormal"><span>Dear Yinglee,</span></p>
<p><span> </span><br /></p><p class="MsoNormal"><span>Thanks for your interest in our work. From my understanding, in the traditional FEM, the space of interest is firstly divided into many non-overlapping subspaces, so-called elements, and the energy is then divided correspondingly. The energy in each element can be determined with the node positions of this element only. This is just the local feature of the traditional FEM. Therefore, the traditional FEM is only accurate for systems with the energy distributed locally, such as the bond energy in terms of pair potential.</span></p>
<p><span> </span><br /></p><p class="MsoNormal"><span>However, for systems with multi-body potentials, it is not easy to accurately assign the energy into subspaces or non-overlapping elements. Therefore, we do not divide the energy in AFEM, and directly compute the first and second order derivatives of the total energy with respect to one specific node position. This node and its neighboring nodes that are needed to compute these derivatives form one AFEM element. With this strategy, we can obtain global stiffness force matrixes without any approximation (e.g. shape function), which ensure the AFEM is as accurate as other standard atomistic simulation methods. Moreover, by taking advantage of mature FEM numerical techniques, AFEM is much faster than existing molecular mechanics methods. </span></p>
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</ul>Fri, 23 Mar 2007 23:50:50 +0000Bin Liucomment 1906 at https://imechanica.orgRE: AFEM
https://imechanica.org/comment/1872#comment-1872
<a id="comment-1872"></a>
<p><em>In reply to <a href="https://imechanica.org/node/1022">Woven Nano-Structure of Carbon Nanotubes</a></em></p>
<div class="field field-name-comment-body field-type-text-long field-label-hidden"><div class="field-items"><div class="field-item even"><p>I also read the paper by Liu, et al. about the atomistic finite element modeling. The main difference between conventional FEM and atomstic finite element modeling, as far as I understand, is the empirical potential field. For instance, in Liu's paper, they used the empirical potential, provided by Brenner or others, for carbon atoms. For potential field, they considered the short-range interaction for CNT such that, for a given atom i, the neighborhood atoms near atom i are taken into account for finding stiffness matrix and force vector based on empirical potential.</p>
<p>The simple mechanics model is working very well for not only nanomaterials (e.g. CNT) but also biomolecules (e.g. proteins), since the dynamics of nanomaterials and/or biomolecules are well described by stiffness matrix and force vector on the basis of empirical potential field (e.g. Brenner's potential for CNT; Tirion's potential for proteins; CHARMM for proteins, etc.). For instance, the stiffness matrix based on Tirion's model (harmonic potential field for short-rang interaction) is sufficient to represent the low-frequency normal mode dynamics of proteins (for details, click <a href="/node/549">here</a>).</p>
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</ul>Thu, 22 Mar 2007 14:50:56 +0000Kilho Eomcomment 1872 at https://imechanica.orgIntresting:)
https://imechanica.org/comment/1871#comment-1871
<a id="comment-1871"></a>
<p><em>In reply to <a href="https://imechanica.org/node/1022">Woven Nano-Structure of Carbon Nanotubes</a></em></p>
<div class="field field-name-comment-body field-type-text-long field-label-hidden"><div class="field-items"><div class="field-item even"><p>I want to know how does the atomic-scale finite element method work and its difference with the tradditional FEM.</p>
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</ul>Thu, 22 Mar 2007 13:43:40 +0000Ying Licomment 1871 at https://imechanica.orgMore information needed
https://imechanica.org/comment/1632#comment-1632
<a id="comment-1632"></a>
<p><em>In reply to <a href="https://imechanica.org/node/1022">Woven Nano-Structure of Carbon Nanotubes</a></em></p>
<div class="field field-name-comment-body field-type-text-long field-label-hidden"><div class="field-items"><div class="field-item even"><p> Bin,</p>
<p>Can you provide more information on this image to help other's understand and facilitate possible discussions? Thanks.</p>
<p>-Teng </p>
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</ul>Mon, 12 Mar 2007 16:24:47 +0000Teng Licomment 1632 at https://imechanica.org