iMechanica - Geometry
https://imechanica.org/taxonomy/term/2099
enPost-doctoral position in the Maddocks group at EPFL
https://imechanica.org/node/22266
<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/11128">thin structures</a></div><div class="field-item odd"><a href="/taxonomy/term/2099">Geometry</a></div><div class="field-item even"><a href="/taxonomy/term/6461">helices</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>Assistantship in the Maddocks group at the EPFL </span><a class="moz-txt-link-freetext" href="http://lcvmwww.epfl.ch">http://lcvmwww.epfl.ch</a> </p>
<p> <span>A position is available to work on a combined analytical, numerical and experimental study of uniform elastic rods in two contexts: </span></p>
<p> 1) the characterisation of helical equilibria, including stability properties, in both the cases of self-avoiding and self-contacting configurations, </p>
<p> and </p>
<p> 2) the equilibria of knots in the presence of friction. </p>
<p> The first project will be carried out in collaboration with the group of Prof J. Kolinski (<a href="https://emsi.epfl.ch">https://emsi.epfl.ch</a>)<span> and the second in collaboration with the group of Prof Pedro Reis (</span><span><span><a href="https://flexlab.epfl.ch/en/" target="_blank">fleXLab: Flexible Structures Laboratory</a>) <br /></span><br /></span><span><span>Preferences will be given to applications at the postdoctoral level, although doctoral level applications will also be considered. </span>Review of applications will start April 15 and will continue until the post is filled. The position is available immediately, with the desired starting date being as soon as practicable, with December 2018 being the latest possible start date. </span></p>
<p> The application procedure and further information is described at <a class="moz-txt-link-freetext" href="http://lcvmwww.epfl.ch/jobs.php">http://lcvmwww.epfl.ch/jobs.php</a></p>
</div></div></div>Thu, 29 Mar 2018 09:01:03 +0000John M. Kolinski22266 at https://imechanica.orghttps://imechanica.org/node/22266#commentshttps://imechanica.org/crss/node/22266Tuning capillary penetration in porous media: Combining geometrical and evaporation effects
https://imechanica.org/node/22250
<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/2508">porous media</a></div><div class="field-item odd"><a href="/taxonomy/term/12020">capillary penetration</a></div><div class="field-item even"><a href="/taxonomy/term/2099">Geometry</a></div><div class="field-item odd"><a href="/taxonomy/term/8270">evaporation</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>Liu, M., Wu, J., Gan, Y., Hanaor, D. A. H., & Chen, C. Q. </span><span><em><strong>Int. J Heat Mass Transf. </strong></em>,</span><span> 2018, 123: 239–250. <a href="https://www.sciencedirect.com/science/article/pii/S0017931017344563">https://www.sciencedirect.com/science/article/pii/S0017931017344563</a></span></p>
<p><span><img src="https://ars.els-cdn.com/content/image/1-s2.0-S0017931017344563-fx1_lrg.jpg" alt="" width="425" height="240" /></span></p>
<p>Capillary penetration of liquids in porous media is of great importance in many applications and the ability to tune such penetration processes is increasingly sought after. In general, liquid penetration can be retarded or restricted by the evaporation of volatile liquid at the surface of the porous media. Moreover, when capillary penetration occurs in a porous layer with non-uniform cross section, the penetration process can be accelerated or impeded by adjusting the section geometry. In this work, on the basis of Darcy’s Law and mass conservation, a theoretical model of capillary penetration combining evaporation effects in two-dimensional homogeneous porous media of varying cross-section is developed and further examined by numerical simulations. The effects of sample geometry and liquid evaporation on capillary penetration are quantitatively analyzed. Results show that the penetration velocity is sensitive to the geometry of the porous layer, and can be tuned by varying the evaporation rate for a given geometry. Under given evaporation conditions, penetration is restricted to a limited region with a predictable boundary. Furthermore, we find that the inhibition of liquid penetration by evaporation can be offset by varying the geometry of the porous layer. The theoretical model is further extended to model the capillary flow in three-dimensional porous media. The interplay of geometry and evaporation during the capillary flow process in 3D conditions is also investigated. The results obtained can be used to facilitate the design of porous structures to achieve tunable capillary penetration for practical applications in various fields.</p>
</div></div></div><div class="field field-name-upload field-type-file field-label-hidden"><div class="field-items"><div class="field-item even"><table class="sticky-enabled">
<thead><tr><th>Attachment</th><th>Size</th> </tr></thead>
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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://imechanica.org/files/IJHMT-2018-Tuning%20capillary%20penetration%20in%20porous%20media_Combining%20geometrical%20and%20evaporation%20effects.pdf" type="application/pdf; length=1173058">IJHMT-2018-Tuning capillary penetration in porous media_Combining geometrical and evaporation effects.pdf</a></span></td><td>1.12 MB</td> </tr>
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</div></div></div>Tue, 20 Mar 2018 07:08:21 +0000Mingchao Liu22250 at https://imechanica.orghttps://imechanica.org/node/22250#commentshttps://imechanica.org/crss/node/22250Geometry and mechanics of thin growing bilayers
https://imechanica.org/node/19862
<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/2099">Geometry</a></div><div class="field-item odd"><a href="/taxonomy/term/17">thin film</a></div><div class="field-item even"><a href="/taxonomy/term/1101">swelling</a></div><div class="field-item odd"><a href="/taxonomy/term/2798">growth</a></div><div class="field-item even"><a href="/taxonomy/term/218">buckling</a></div><div class="field-item odd"><a href="/taxonomy/term/5088">large deformations</a></div><div class="field-item even"><a href="/taxonomy/term/10888">plate and shells</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>Matteo Pezzulla, Gabriel P. Smith, Paola Nardinocchi, and Douglas P. Holmes, <em>Soft Matter</em>, <strong>12</strong>, 4435-4442, (2016).</p>
<p> </p>
<p>We investigate how thin sheets of arbitrary shapes morph under the isotropic in-plane expansion of their top surface, which may represent several stimuli such as nonuniform heating, local swelling and differential growth. Inspired by geometry, an analytical model is presented that rationalizes how the shape of the disk influences morphing, from the initial spherical bending to the final isometric limit. We introduce a new measure of slenderness that describes a sheet in terms of both thickness and plate shape. We find that the mean curvature of the isometric state is three fourths the natural curvature, which we verify by numerics and experiments. We finally investigate the emergence of a preferred direction of bending in the isometric state, guided by numerical analyses. The scalability of our model suggests that it is suitable to describe the morphing of sheets spanning several orders of magnitude.</p>
<p> </p>
<p><img src="http://www.bu.edu/moss/files/2016/05/Figure1.jpg" alt="" width="893" height="502" /></p>
<p>Link: <a href="http://pubs.rsc.org/en/content/articlelanding/2016/sm/c6sm00246c#!divAbstract">http://pubs.rsc.org/en/content/articlelanding/2016/sm/c6sm00246c#!divAbstract</a></p>
<p>arXiv: <a href="http://arxiv.org/abs/1509.05259">http://arxiv.org/abs/1509.05259</a></p>
<p> </p>
</div></div></div>Mon, 16 May 2016 14:27:38 +0000Douglas P Holmes19862 at https://imechanica.orghttps://imechanica.org/node/19862#commentshttps://imechanica.org/crss/node/19862Call for Papers: Shape Modeling International 2014 (Deadline July 7, 2014)
https://imechanica.org/node/16842
<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/151">Conference</a></div><div class="field-item odd"><a href="/taxonomy/term/2099">Geometry</a></div><div class="field-item even"><a href="/taxonomy/term/9930">graphics</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> </p>
<p><span><span> </span></span><span><strong><span>DEADLINE EXTENDED TO </span></strong><strong><span><a href="http://airmail.calendar/2014-07-08%2008:00:00%20EDT">JULY 8, 2014 12:00 GMT</a>/UTC (</span></strong><span><span><a href="http://airmail.calendar/2014-07-07%2012:00:00%20EDT">JULY 7</a>, 2014 </span><a href="http://en.wikipedia.org/wiki/Anywhere_on_Earth">AoE</a>)</span></span>
</p><p><span><span>International Convention on SPM/SMI 2014 - </span></span><a href="http://www.mae.cuhk.edu.hk/~smi2014/"><span>Shape Modeling International</span></a></p>
<p><a href="http://www.mae.cuhk.edu.hk/~smi2014/">http://www.mae.cuhk.edu.hk/~smi2014/</a><span><span> </span></span><span><span> </span></span><span><span>Call for Papers: Shape Modeling International 2014</span></span>
</p><p><span><span>Shape Modeling International 2014 (SMI 2014) will be held on Oct 28–30, 2014, in the Chinese University of Hong Kong, Hong Kong.</span></span></p>
<p><span>SMI will be co-located with the <strong>Symposium on Solid and Physical Modeling 2014 (SPM 2014).</strong></span></p>
<p><span><span> </span></span><span><span> </span></span><span><span><strong>General Information</strong></span></span>
</p><p><span><span>Shape Modeling International is the premier international forum for the dissemination of new mathematical theories and novel computational techniques for modeling, simulating, and processing digital representations of shapes and their properties, to a community of researchers, developers, practitioners, and students in academia and industry, across a wide range of fields. In 2001, SMI merged with the Implicit Surface Workshop, and is now run as an annual event alternating between Asia, Europe, and America. <strong>SMI 2014 will immediately follow the Symposium on Solid and Physical Modeling 2014(SPM 2014), to be held on <a href="http://airmail.calendar/2014-10-26%2012:00:00%20EDT">Oct 26–28, 2014</a>, in the Chinese University of Hong Kong, Hong Kong, China.</strong></span></span></p>
<p><span><span>Original research papers accepted for presentation at the conference, both full-length (up to 14 pages) and short (6–8 pages), will be published as a special issue of</span> <span>Computers & Graphics</span><span>.</span></span></p>
<p><span><span> </span></span><span><span> </span></span><span><span><strong>Conference Topics</strong></span></span>
</p><p><span><span>Papers presenting original research are being sought in all areas of geometry processing and its applications, including (but not limited to)</span></span></p>
<ul><li><span>- isogeometric analysis</span></li>
<li><span>- barycentric coordinates</span></li>
<li><span>- meshing, remeshing, and parameterization</span></li>
<li><span>- computational topology</span></li>
<li><span>- discrete differential geometry</span></li>
<li><span>- curves and surfaces</span></li>
<li><span>- implicit surfaces</span></li>
<li><span>- shape transformation, manipulation, and deformation</span></li>
<li><span>- interactive design and editing</span></li>
<li><span>- sketching and 3D input</span></li>
<li><span>- acquisition and reconstruction</span></li>
<li><span>- healing, resampling, and shape completion</span></li>
<li><span>- correspondence and registration</span></li>
<li><span>- shape analysis and semantics</span></li>
<li><span>- shape descriptors, matching and retrieval</span></li>
<li><span>- features extraction and classification</span></li>
<li><span>- compression and streaming</span></li>
<li><span>- subdivision surfaces and methods</span></li>
<li><span>- parametric and procedural models</span></li>
<li><span>- volume and multi-dimensional modeling</span></li>
<li><span>- multi-resolution techniques</span></li>
<li><span>- physics-based techniques</span></li>
</ul><ul><li><span><span> </span></span><span><span> </span></span><span><span><strong>Important Dates (Updated)</strong></span></span> <span><span><strong>Full paper submission due: <span><span><a href="http://airmail.calendar/2014-07-08%2012:00:00%20EDT">JULY 8, 2014 12:00</a> GMT/UTC (</span></span><span><span><a href="http://airmail.calendar/2014-07-07%2012:00:00%20EDT">JULY 7, 2014</a> </span><a href="http://en.wikipedia.org/wiki/Anywhere_on_Earth">AoE</a>)</span><br /></strong></span></span><em><span><strong>If you have already submitted a manuscript and would like to make changes to it, please <a href="mailto:computers-and-graphics@inesc-id.pt">contact the Editor-in-Chief</a> directly.</strong></span></em><span><em><span><strong> </strong></span></em></span><span><span>Review due: <a href="http://airmail.calendar/2014-07-30%2012:00:00%20EDT">July 30</a>, 2014<br />Submission of revision: <a href="http://airmail.calendar/2014-08-15%2012:00:00%20EDT">August 15, 2014</a><br />Final Accept/Reject Decisions: <a href="http://airmail.calendar/2014-09-15%2012:00:00%20EDT">September 15, 2014</a> Final version due: <a href="http://airmail.calendar/2014-09-30%2012:00:00%20EDT">September 30, 2014</a></span></span><span>SMI 2014: October 28–30, 2014</span><span><span><span> </span></span></span> <span><span><strong> </strong></span></span><span><span><strong>Committee</strong></span></span>
<p><span><span><strong>Program Chairs:</strong></span></span></p>
<p><span><span>Eitan Grinspun (Columbia University, USA)<br />Alexander A. Pasko (Bournemouth University, UK)<br />Charlie C.L. Wang (The Chinese University of Hong Kong, Hong Kong) </span></span></p>
<p><span><strong>Convention Co-chairs:</strong></span></p>
<p><span><span>Shuming Gao (Zhejiang University, China)<br />John C. Hart (University of Illinois, Urbana-Champaign, USA)<br />Joaquim Jorge (Instituto Superior Técnico, Portugal)<br />Konrad Polthier (Freie Universität Berlin, Germany)<br />Wenping Wang (Hong Kong University, Hong Kong)</span><span><br /></span></span></p>
<p><span><span><strong>Organization Chair:</strong></span></span></p>
<p><span><span><span>Charlie C.L. Wang (The Chinese University of Hong Kong, Hong Kong)</span> <span>Conference Website</span></span></span></p>
<p><span><span><a href="http://www.mae.cuhk.edu.hk/~smi2014/">http://www.mae.cuhk.edu.hk/~smi2014/</a></span></span></p>
</li>
</ul><p><span> </span></p>
</div></div></div>Tue, 01 Jul 2014 18:12:40 +0000Eitan Grinspun16842 at https://imechanica.orghttps://imechanica.org/node/16842#commentshttps://imechanica.org/crss/node/16842iMechanica Journal Club (October 2013): Contortion of thin elastic rods
https://imechanica.org/node/15442
<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/347">elasticity</a></div><div class="field-item odd"><a href="/taxonomy/term/855">journal club</a></div><div class="field-item even"><a href="/taxonomy/term/1636">experiments</a></div><div class="field-item odd"><a href="/taxonomy/term/2099">Geometry</a></div><div class="field-item even"><a href="/taxonomy/term/9194">Thin elastic rods</a></div><div class="field-item odd"><a href="/taxonomy/term/9195">geometric nonlinearities</a></div><div class="field-item even"><a href="/taxonomy/term/9196">mechanical instabilities</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>
</p>
<p>
There has been a recent revival of the study of thin elastic rods from the mechanics, physics and computer science communities. From a fundamental perspective, predicticting the geometrically-nonlinear behavior of thin rods in the post-buckling regime is a challenging endeavor. Moreover, there are many modern industrial contexts for which rationalizing the mechanics of thin elastic filamentary structures is both relevant and timely. The role of intrinsic natural curvature of an elastic filament, which is often overlooked, is of particular interest since it can dramatically, quantitatively and qualitatively change the behavior of the system.
</p>
<p>
<strong>1. The Mechanics of thin elastic rods - past and present:</strong>
</p>
<p align="justify">
Thin elastic rods are long and slender structures that are nearly one-dimensional; their length is significantly larger than their diameter (Fig. 1). Instances of thin rods as structural elements appear in a wide range of contexts and length scales, both in the natural and built environment. Under different loading conditions, these structures can undergo mechanical instabilities that lead to large displacements and geometrically-nonlinear configurations that result in mechanical behavior that is challenging to rationalize and predict. The ‘ease’ and ‘softness’ in their reconfiguration provides outstanding kinematic freedom for function and practical applications. Examples include DNA [1], coiling of carbon nanotubes [2], bacteria flagella [3], conducting elements for stretchable electronics [4], filamentary plant structures [5], human hair [6], flexible cables and pipes [7] and coiled-tubing operations in the oil-gas industry [8].
</p>
<p>
</p>
<p> <img src="http://web.mit.edu/preis/www/images/iMechanica_Oct2013/PedroReis_iMechanica_Fig1.jpg" alt="iMechanica Journal Club October 2013 | Pedro Reis | MIT" title="Contorting Thin Elastic Rods | Fig. 1" hspace="10" vspace="10" width="500" height="329" /></p>
<p>
</p>
<p>
<strong>Figure 1.: Thin Elastic Rods. </strong>a) Ensemble of thin elastic rods exhibiting geometrically-nonlinear behavior. b) Kinematics of a Cosserat rod in the global cartesian frame <em>(x,y,z)</em> The configuration of the rod is defined by its centerline, <em><strong>r</strong>(s)</em>, as a function of the arclength, <em>s</em>. The orientation of each mass point of the rod is represented by an orthonormal basis <em>(<strong>d</strong>1(s), <strong>d</strong>2(s),<strong>d</strong>3(s))</em>, called the directors, where <em><strong>d</strong>3(s)</em> is constrained to be tangent to <em><strong>r</strong>(s)</em> [6].
</p>
<p align="justify">
The analysis of the mechanics of elastic rods has a long and distinguished history, a thorough description of which is beyond the scope of this post. In short, the earlier studies on the mechanics of rods are often traced back to the experimental buckling investigations of Musschenbroek in 1721 [6] and the analytic work of Euler in 1744 [9] for planar deformations of straight rods. Kirchhoff later derived the general equations for elastic rods in 1859 [10]. Kirchhoff’s kinetic analogy identified a correspondence between the equilibria of a rod and the motion of a spinning top [11]. This elegant connection allowed for a deeper understanding of mechanical instabilities and nonlinear equilibrium configurations of rods with natural curvature [12].
</p>
<p align="justify">
Many people, especially since the 1980’s, have been making important contributions in this area. A far-from-exhaustive list of researchers who have been making substantial contributions to the field is given at the end of this post. For a more detailed account of the mechanics of elastic rods, including a review of the modern state-of-the-art of the theory, we suggest the recent book by Basile Audoly and Yves Pomeau - “Elasticity and Geometry: From Hair Curls to the Non-linear response of Shells” (OUP) [6].
</p>
<p><strong>2. Our take on thin rods:</strong></p>
<p align="justify">
In my research group we have recently revisited the classic field of the mechanics of thin elastic rods and have been developing a research program that combines experimental, numerical and theoretical efforts. Surely, a lot has been done by previous giants in the field but we have also identified a number of new opportunities. One specific direction that we are currently pursuing involves developing tools for better understanding the non-trivial role of intrinsic natural curvature on thin rods. This is particularly relevant to many engineering problems where fibers, filaments, cables and pipes are spooled for storage and transport, which may irreversibly impart a natural curvature that must be treated as an independent variable. As others before, we have found that intrinsic natural curvature can lead to nontrivial and counter-intuitive effects that can dramatically change, both qualitatively and quantitatively, the behavior of the system, thereby calling for a thorough predictive physical understanding.
</p>
<p align="justify">
<strong>2.1. Precision model experiments:</strong>
</p>
<p align="justify">
During the deformation process of a thin rod, the large displacements involved can lead to non-negligible geometric nonlinearities, even if the material properties remain linear, that are mostly system independent. These universal modes of deformation underlie the fact that similar phenomena can be observed over a wide range of lengthscales (small and large). This opens the way to approach application in a unified way, without the need to work at the original scale that motivated the problem. In this context, we have been developing an experimental methodology for studying the mechanics of geometrically-nonlinear scenarios that has <em>Precision Model Experiments</em> (desktop-scale) at its basis. These model experiments allow for a reduction of the problem to its bare essential physical ingredients, that take advantage of the geometrically-rooted behavior of thin rods. Given the often non-trivial and counter-intuitive behavior of these systems, in addition to their use for model/numerics validation purposes, these model experiments also play an invaluable role as a tool for discovery and exploration.
</p>
<p> <img src="http://web.mit.edu/preis/www/images/iMechanica_Oct2013/PedroReis_iMechanica_Fig2.jpg" alt="iMechanica Journal Club October 2013 | Pedro Reis | MIT" title="Contorting Thin Elastic Rods | Fig. 2" hspace="10" vspace="10" width="700" height="240" /></p>
<p>
<strong>Figure 2.: Experiments with thin elastic rods.</strong> a,b) Fabrication of our thin rods with custom natural curvature, <em>ko</em>, through casting of an elastomere inside a PVC flexible tube wound around a rigid cylinder of set diameter. c) Collection of elastic rods with different natural curvatures, <em>ko</em>. d) The writhing experiment. A naturally curved elastomeric rod is clamped to two concentrically aligned drill chucks, which allow for the end-to-end displacement or rotation of the extremities to be imposed.
</p>
<p align="justify">
Using rapid prototyping techniques, we cast our own rods with full custom control of material and geometric properties (Fig. 2). A flexible PVC tube, which acts as a mold (inner and outer diameter, <em>Di=3.1mm</em> and <em>Do=5mm</em>, respectively) is first wound around a cylinder of external radius <em>Re</em> (see Fig. 2a,b). Vinylpolysiloxane (VPS), an elastomer, is then injected into the PVC tube, which eventually cross-links at room temperature. After a setting period (typically of 24 hours) the outer flexible PVC pipe is cut to release the inner slender VPS elastic rod with constant natural curvature <em>ko=1/(Re+Do/2)</em>. Using cylinders with different radius <em>Re</em>, we can systematically produce rods with different custom values of natural curvature, typically in the range 0<<em>ko</em><60m-1, which allow <em>ko</em> to be treat it as a control parameter that can be varied systematically. Whereas we also have control over the other geometric and material parameters, we typically fix them at: Young’s modulus, <em>E~0.3-1.3MPa</em>, density <em>ρ=1200 kg/m-3</em>, Poisson’s ratio <em>ν~0.5</em> and rod’s radius <em>R~1mm</em>. In Fig. 2c we show a collection of rods with different values of intrinsic natural curvature <em>ko</em>.
</p>
<p align="justify">
<strong>2.2. Path-following numerical tools:</strong>
</p>
<p align="justify">
In parallel to the physical experiments we have developed our own simulation tool that enables us to obtain the equilibrium configurations, as well as compute the full bifurcation diagrams of the system, which may include multiple stable and unstable states. We used MANlab [13], a continuation software package that we recently adapted for the specific use with elastic rods [14, 15]. The 3D kinematics of the rod is treated in a geometrically exact way by parameterizing the position of the centerline and making use of quaternions to represent the orientation of the material frame. The rod is assumed to be inextensible and unshearable. The equilibrium equations and the stability of their solutions are derived from the mechanical energy which takes into account the contributions due to internal moments (bending and twist), external forces and torques. Our use of quaternions allows for the equilibrium equations to be written in a quadratic form and solved efficiently with an asymptotic numerical continuation method. This finite element perturbation technique gives interactive access to semi-analytical equilibrium branches, in contrast with the individual solution points obtained from classical minimization or predictor–corrector techniques. Our simulation tool based on MANlab has similar capabilities to the path-following software AUTO [16] but with a number of added advantages including interactivity, user-friendliness and efficiency. More details about our numerical method can be round in the following reference [14]:
</p>
<p>
<a href="http://web.mit.edu/preis/www/mypapers/reis_JMPS_ContinuationRods_2013.pdf" title="Continuation of equilibria and stability of slender elastic rods using an asymptotic numerical method">A.Lazarus, J.T. Miller and P.M. Reis "Continuation of equilibria and stability of slender elastic rods using an asymptotic numerical method"<br />
J. Mech. Phys. Solids., 61(8), 1712 (2013). </a>
</p>
<p>
</p>
<p><strong>3. The writhing of a thin rod as a test-bed:<br /></strong></p>
<p align="justify">
As an example of our approach, we test-ride our experimental and numerical tools by tackling the classic problem of writhing of a thin rod (which has received much studies in the past [17]) and has become a canonical model-system in which to investigate the equilibrium configurations, stability and spatial localization of contorted filamentary structures. In Fig. 2d we show a photograph of our experimental set-up. Upon fabricating our own rods as described above, the rod sample is then suspended between two horizontal concentric chucks which are used to apply an end-to-end rotation to the rod, while fixing the distance between the clamps. We have also studied the converse scenario of varying the end-to-end displacement of the clamps without rotation. We highlight that the primary control parameter in this study is the intrinsic natural curvature of the rod, which we vary systematically. More details on this study can be found in [15]:
</p>
<p>
<a href="http://web.mit.edu/preis/www/mypapers/lazarus_reis_SoftMatter_ContorningRods.pdf" title="Contorting a heavy and naturally curved elastic rod">A.Lazarus, J.T. Miller, M. Metlitz and P.M. Reis "Contorting a heavy and naturally curved elastic rod", Soft Matter, 9 (34), 8274 (2013). </a>
</p>
<p align="justify">
A variety of experimental and numerical configurations for rods with increasing end-to-end rotation are presented in Fig. 3. Fig. 3a presents configurations for a naturally straight rod (<em>ko=0 m-1</em>) and Fig. 3b presents configuration for a naturally straight rod (<em>ko=44.8 m-1</em>), with the two cases being strikingly different from both qualitative and quantitative viewpoints.
</p>
<p>
</p>
<p> <img src="http://web.mit.edu/preis/www/images/iMechanica_Oct2013/PedroReis_iMechanica_Fig3.jpg" alt="iMechanica Journal Club October 2013 | Pedro Reis | MIT" title="Contorting Thin Elastic Rods | Fig. 3" hspace="10" vspace="10" width="700" height="231" /></p>
<p>
</p>
<p>
<strong>Figure 3.: The writhing experiment. </strong>Top views of experimental and numerical equilibrium conﬁgurations for increasing values of the end-to-end rotation angle. The experimental pictures have a black background and the simulations have a white background. The simulation results are rendered to visualize twist by using bi-color rods. a) <em>ko=0 m-1</em> b) <em>ko=44.8 m-1</em>.
</p>
<p align="justify">
In the video below we present the corresponding comparison between experimental and numerical configurations, as a function of end-to-end rotation. Each of the four panels in the video corresponds to rods with increasing natural curvature and the video stops as soon as a plectoneme (localized deformation) forms. Again, we find excellent quantitative and qualitative agreement between the two, with no fitting parameters. Note that we also take the effect of self-weight into account in the simulations.
</p>
<object classid="d27cdb6e-ae6d-11cf-96b8-444553540000" codebase="http://download.macromedia.com/pub/shockwave/cabs/flash/swflash.cab#version=6,0,40,0" width="600" height="337">
<embed type="application/x-shockwave-flash" width="600" height="337" src="http://www.youtube.com/v/wjfUVweSEcQ"></embed></object><p>
</p>
<p align="justify">
We have uncovered the original effect that weight delays the effect of natural curvature. Below a critical value of k_o^{crit}, gravity balances the imposed geometry and the heavy rod can be considered as being naturally straight, albeit with a small imperfection k_o. In contrast, above k_o^{crit}, the effect of natural curvature is significant and sufficient to break the symmetry of the rod’s pattern formation. We propose that this critical curvature is set by the inverse of the elastro-gravity lengthscale, <em>1/L_gb=[EI/(ρg S)]^{-1/3}</em>, where <em>EI</em> is the bending modulus of the rod, <em>ρS</em> is its linear mass density and <em>g</em> is the gravitational acceleration. Counterintuitively, we also find that imparting a constant natural curvature to our rods (essentially adding a geometric imperfection to the stress-free configuration) results in considerably postponing (in our particular study by approximately 43%) the emergence of the plectoneme instability, which is often synonymous of failure in practical systems. This study highlights the power of combining our precision model experiments, which are used primarily as a tool of discovery in addition to validation, with our own simulation tools, which are then used to help rationalize the process by enabling access to quantities unavailable experimentally. More details can be found in [15].
</p>
<p>
<strong>4. Ongoing work:</strong></p>
<p align="justify">
Geared with both our precision model experiment approach and our simulation toolbox, we are now actively pursuing a variety of other problems involving geometrically-nonlinear configuration of thin rods in a variety of configurations, some of which with direct industrial relevance (and sponsorship). In collaboration with Eitan Grinpun’s group (Columbia University), we are also exploring the porting of a simulation tool - Discrete Elastic Rod Method [18] - that was originally developed in the context of physically-based computer animation, into engineering as a predictive tool. We hope to share these latest developments with the community in the near future.
</p>
<p>
<strong>5. Concluding thoughts:</strong></p>
<p align="justify">
In summary, we have identified new opportunities in reviving the study of the mechanics of thin rods, with a focus on geometrically-nonlinear behavior in the far-from-threshold post-buckling regime. In addition to a mechanism for validation, precision model experiments can play an important role as a tool for exploration and discovery in these nonlinear and often counter-intuitive processes. The role of intrinsic natural curvature of an elastic filament, which is often overlooked, is of particular interest since it can dramatically, quantitatively and qualitatively change the behavior of the system. Natural curvature arises naturally in many instances of filamentary structures during their fabrication, storage and transport in spools. These problems in naturally curved elastic rods pose significant challenges from a fundamental perspective, while having direct relevance and impact on practical applications.
</p>
<p>
<strong>Questions for discussion:</strong></p>
<p align="justify">
I would like to finish by opening the “i-floor” for discussion by posing a few questions:
</p>
<ul><li>What opportunities (if any) do you see in reviving the classic subject of the mechanics of thin rods in modern contexts? ‘Is it all done’ or do you envision exciting open research directions?</li>
<li>What modern tools (experimental, numerical and theoretical) do you use to approach this class of problems?</li>
<li>Have you come across challenges in describing the geometrically-nonlinear behavior of thin rods/filaments in your own domain?</li>
<li>Are you currently working on problems involving the mechanics of thin elastic filaments? If so, could you please share your recent work?</li>
</ul><p> </p>
<p align="justify">
<strong>Acknowledgments:</strong> I would like to thank the members of my research group, the EGS.Lab at MIT, for all their hard work and creativity, especially, Arnaud Lazarus, James Miller, Tianxiang Su and Khalid Jawed who have worked on some of the material mentioned in this post. I am also grateful to my colleagues Eitan Grinspun, Basile Audoly, Katia Bertoldi and Nathan Wicks for fruitful collaborations on the mechanics of thin rods. Finally, I am grateful to NSF (CMMI-1129894), Schlumberger and Saint-Gobain for financial support.
</p>
<p>
<strong>References most directly related to this post:</strong></p>
<p align="justify">
<a href="http://web.mit.edu/preis/www/mypapers/lazarus_reis_SoftMatter_ContorningRods.pdf" title="Contorting a heavy and naturally curved elastic rod">A.Lazarus, J.T. Miller, M. Metlitz and P.M. Reis "Contorting a heavy and naturally curved elastic rod", Soft Matter, <strong>9</strong> (34), 8274 (2013). </a>
</p>
<p align="justify">
<a href="http://web.mit.edu/preis/www/mypapers/reis_JMPS_ContinuationRods_2013.pdf" title="Continuation of equilibria and stability of slender elastic rods using an asymptotic numerical method">A.Lazarus, J.T. Miller and P.M. Reis "Continuation of equilibria and stability of slender elastic rods using an asymptotic numerical method" J. Mech. Phys. Solids., <strong>61</strong>(8), 1712 (2013). </a>
</p>
<p align="justify">
For more information on research on the mechanics of slender structures from our research group - <a href="http://web.mit.edu/preis/www/" title="Pedro Reis | EGS.Lab | Elasticity, Geometry and Statistics Laboratory | MIT">EGS.Lab: Elasticity, Geometry and Statistics Laboratory</a> (MIT) - please visit: <a href="http://web.mit.edu/preis/www/" title="Pedro Reis | EGS.Lab | Elasticity, Geometry and Statistics Laboratory | MIT"> http://web.mit.edu/preis/www/</a>
</p>
<p>
<strong>Active Mechanicians working on thin rods:</strong> </p>
<p align="justify">
Here is a list of researchers who have been making substantial contributions to the field of the mechanics of thin elastic rods (in alphabetical order):
</p>
<ul><li><a href="http://www.lmm.jussieu.fr/~audoly/" title="Basile Audoly (CNRS/UPMC)">Basile Audoly</a> (CNRS/UPMC),</li>
<li><a href="http://www.enm.bris.ac.uk/anm/staff/arc.html" title="Alan Champneys (Bristol)">Alan Champneys</a> (Bristol),
</li>
<li><a href="http://www.mechanics.rutgers.edu/BDC.html">Bernard Coleman</a> (Rutgers),</li>
<li><a href="http://www.damtp.cam.ac.uk/user/gold/" title="Raymond Goldstein (Cambridge)">Raymond Goldstein</a> (Cambridge),</li>
<li><a href="http://www.maths.ox.ac.uk/people/profiles/alain.goriely">Alain Goriely</a>, (Oxford),</li>
<li><a href="http://www.cs.columbia.edu/~eitan/">Eitan Grinspun</a>, (Columbia)</li>
<li><a href="http://www.math.cornell.edu/m/People/Faculty/healey">Tim Healey</a> (Cornell),</li>
<li><a href="http://www.ucl.ac.uk/~ucesgvd/" title="Gert van der Heijden (UCL)">Gert van der Heijden</a> (UCL), </li>
<li><a href="http://www.math.umbc.edu/~khoffman/">Kathleen Hoffmann</a> (Maryland)</li>
<li><a href="http://lcvmwww.epfl.ch/~jhm/" title="John Maddocks (EPFL)">John Maddocks</a> (EPFL), </li>
<li><a href="http://www.seas.harvard.edu/softmat/" title="L. Mahadevan (Harvard)">L. Mahadevan (Harvard)</a>,</li>
<li><a href="http://www.haverford.edu/math/rmanning.html">Rob Manning</a>, (Haverford),</li>
<li><a href="http://www.lmm.jussieu.fr/~neukirch/" title="Sébastien Neukirch (CNRS/UPMC)">Sébastien Neukirch</a> (CNRS/UPMC),</li>
<li><a href="http://www.me.berkeley.edu/faculty/oreilly/" title="Oliver M. O'Reilly (UC Berkeley)">Oliver O'Reilly</a> (UC Berkeley)</li>
<li> <a href="http://people.mcgill.ca/michael.paidoussis/" title="Michael P Paidoussis (McGill)">Michael P Paidoussis</a> (McGill), </li>
<li><a href="http://www.seas.upenn.edu/directory/profile.php?ID=75" title="Prashant Purohit (UPenn)">Prashant Purohit</a> (UPenn),</li>
<li><a href="http://www.math.pitt.edu/~swigon/">David Swigon</a>, (Pittsburgh)</li>
<li> <a href="http://appliedmath.arizona.edu/profile-michael-tabor" title="Michael Tabor (Arizona)">Michael Tabor</a> (Arizona), </li>
<li><a href="http://www.ucl.ac.uk/~ucess21/" title="J. Michael Thompson (UCL)">J. Michael Thompson</a> (UCL).</li>
</ul><p>
Hopefully your contributions and replies below to this post will help further complement and increase this far-from-exhaustive list. Feel free to continue to send suggestions to add to this list.
</p>
<p>
<strong>References:</strong>
</p>
<p align="left">
[1] S. Neukirch, Phys. Rev. Lett., <strong>93</strong>, 198107 (2004).
</p>
<p align="left">
[2] N. Geblinger, A. Ismach and E. Joselevich, Nature Nanotech., <strong>3</strong>, 195 (2008).
</p>
<p align="left">
[3] K. Son, J.S. Guasto and R, Stocker, Nature Physics <strong>9</strong>, 494 (2013).
</p>
<p align="left">
[4] Y. Sun, W.M. Choi, H. Jiang, Y.Y. Huang, and J.A. Rogers, Nature Nanotech. <strong>1</strong>(3) 201 (2006).
</p>
<p align="left">
[5] A. Goriely, M. Tabor. Phys. Rev. Lett. <strong>80</strong>(7) 1564 (1998).
</p>
<p align="left">
[6] B. Audoly and Y. Pomeau. “Elasticity and geometry: from hair curls to the non-linear response of shells.” Oxford: Oxford University Press (2010).
</p>
<p align="left">
[7] S. Goyal, N. Perkins and C. Lee, Int. J. Nonlinear Mech., <strong>43</strong>, 65 (2008).
</p>
<p align="left">
[8] N. Wicks, B.L. Wardle and D. Pafitis. Int. J. of Mech. Sci. <strong>50</strong>(3) 538 (2008).
</p>
<p align="left">
[9] R. Levien, "The Elastica: A Mathematical History". UCB/EECS-2008-103, EECS Department, University of California, Berkeley.
</p>
<p align="left">
[10] E.H. Dill, Arch. Hist. Exact Sci. <strong>44</strong>(1) 1 (1992).
</p>
<p align="left">
[11] M. Davies and F. Moon, Chaos, <strong>3</strong>, 93 (1993).
</p>
<p align="left">
[12] A. Goriely and M. Tabor, Physica D 105, <strong>20</strong> (1997); A. Champneys, G. Van der Heijden, and J. Thompson, Philos. Trans. R. Soc. London, Ser. A <strong>355</strong>, 2151 (1997); P. Furrer, R. Manning, and J. Maddocks, Biophys. J. <strong>79</strong>, 116 (2000).
</p>
<p align="left">
[13] S. Karkar, R. Arquier, and B. Cochelin, User Guide MANLAB 2.0 (2011).
</p>
<p align="left">
[14] A. Lazarus, J. Miller, and P.M. Reis, J. Mech. Phys. Solids <strong>61</strong>, 1712 (2013).
</p>
<p align="left">
[15] A. Lazarus, J. Miller, M. Metlitz, and P.M. Reis, Soft Matter <strong>9</strong> (34), 8274 (2013).
</p>
<p align="left">
[16] E.J. Doedel, "AUTO: A program for the automatic bifurcation analysis of autonomous systems." Congr. Numer. <strong>30</strong> 265-284 (1981).
</p>
<p align="left">
[17] A. Greenhill, Proc. – Inst. Mech. Eng., <strong>34</strong>, 182 (1883). A. Love, "A treatise on the mathematical theory of elasticity", University Press, (1920). J. Coyne, IEEE J. Oceanic Eng.,<strong>15</strong>, 72 (1990). J. Thompson and A. Champneys, Proc. R. Soc. London, Ser. A, <strong>452</strong>, 117 (1996). A. Goriely and M. Tabor, Proc. R. Soc. London, Ser. A, <strong>454</strong>, 3183 (1998). A. Goriely and M. Tabor, Proc. R. Soc. London, Ser. A, <strong>453</strong>, 2583 (1997).
</p>
<p align="left">
[18] M. Bergou, M. Wardetzky, S. Robinson, B. Audoly and E. Grinspun "Discrete elastic rods." ACM Transactions on Graphics (TOG). <strong>27</strong>(3) 63 (2008).
</p>
<p align="left">
</p>
</div></div></div>Mon, 07 Oct 2013 00:00:58 +0000Pedro Reis15442 at https://imechanica.orghttps://imechanica.org/node/15442#commentshttps://imechanica.org/crss/node/15442[FEM] How we are using shell geometry properties in time of calculation?
https://imechanica.org/node/12686
<div class="field field-name-body field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"><p>
Hello.
</p>
<p>
I'm interested in methods and approaches for FEM, that are used for taking into account the shell geometry properties (curvatures, quadratic forms) in time of calculation. I'm not telling about NURBS, the shells are defyned by analytical expressions: sphere, Monge surfaces, Joachimstahl surface. In Zienkewich book they are use the flat elements, but in time of calculation they don't use the shell geometry, only for mesh generation. Maybe someone somehow have used in shape functions the coefficients of quadratic forms...
</p>
<p>
Could anyone get references to articles about such informaiton.
</p>
<p>
Best regards.
</p>
<p>
</p>
</div></div></div><div class="field field-name-taxonomy-forums field-type-taxonomy-term-reference field-label-above"><div class="field-label">Forums: </div><div class="field-items"><div class="field-item even"><a href="/forum/109">Ask iMechanica</a></div></div></div><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/128">education</a></div></div></div><div class="field field-name-taxonomy-vocabulary-8 field-type-taxonomy-term-reference field-label-above"><div class="field-label">Free Tags: </div><div class="field-items"><div class="field-item even"><a href="/taxonomy/term/751">Shell</a></div><div class="field-item odd"><a href="/taxonomy/term/2099">Geometry</a></div><div class="field-item even"><a href="/taxonomy/term/7657">quadratic forms</a></div></div></div>Fri, 29 Jun 2012 20:29:07 +0000IvanKushnarenko12686 at https://imechanica.orghttps://imechanica.org/node/12686#commentshttps://imechanica.org/crss/node/12686Minisymposium on "Applications of computational geometry in analysis" within ECCOMAS 2012
https://imechanica.org/node/11487
<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/162">computational mechanics</a></div><div class="field-item odd"><a href="/taxonomy/term/451">meshfree methods</a></div><div class="field-item even"><a href="/taxonomy/term/2099">Geometry</a></div><div class="field-item odd"><a href="/taxonomy/term/2356">differential geometry</a></div><div class="field-item even"><a href="/taxonomy/term/6857">subdivision</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">
</p>
<p class="p1">
We would like to draw your attention to the minisymposium on "Applications of<span class="s1"> </span>computational geometry in analysis" within ECCOMAS 2012. The conference<span class="s1"> </span>will be held in Vienna on September 10-14, 2012. Please see below for a description of the mini-symposium and <a href="http://eccomas2012.conf.tuwien.ac.at/"><span class="s2"><strong>http://eccomas2012.conf.tuwien.ac.at/</strong></span></a> for<span class="s1"> </span>details about the conference.
</p>
<p class="p2">
</p>
<p class="p1">
If you are able to participate a short abstract is due by December 15, 2011,
</p>
<p class="p1">
Best regards,<span class="s1"><br /></span>Fehmi Cirak (Cambridge), Marino Arroyo (UPC Barcelona), N. Sukumar (UC Davis)
</p>
<p class="p1">
---<span class="s1"><br /></span>Applications of computational geometry in analysis (MS121)
</p>
<p class="p1">
The past few years have seen an increasing convergence of methods used in<span class="s1"> </span>computational mechanics, graphics, animation and vision. This minisymposium<span class="s1"> </span>will provide a common forum for exchange of ideas, methods and results<span class="s1"><br /></span>concerning the application of computational geometry in computational<span class="s1"> </span>mechanics. The following list may serve as a guideline for potential contributions:
</p>
<p class="p1">
- Parametric, implicit and point based geometry representations and<span class="s1"> </span>tightly integrated analysis techniques<span class="s1"><br /></span> - Applications of multiresolution geometry processing in analysis <span class="s1"><br /></span> - Subdivision surfaces/volumes<span class="s1"><br /></span> - Convex approximation schemes such as max-ent <span class="s1"><br /></span> - Basis functions for arbitrary polygons and polyhedrons <span class="s1"><br /></span> - Meshfree approaches based on Voronoi diagrams <span class="s1"><br /></span> - Variationally motivated discrete geometry and mesh processing techniques <span class="s1"><br /></span> - Discrete differential geometry of manifolds
</p>
<p>
</p>
</div></div></div>Tue, 29 Nov 2011 12:25:13 +0000Fehmi Cirak11487 at https://imechanica.orghttps://imechanica.org/node/11487#commentshttps://imechanica.org/crss/node/11487Postdoctoral position at the University of Oxford: Hierarchical scaling, structure, and mechanics of filamentary assemblies
https://imechanica.org/node/7607
<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/2099">Geometry</a></div><div class="field-item odd"><a href="/taxonomy/term/4839">Rod mechanics</a></div><div class="field-item even"><a href="/taxonomy/term/4840">applied mathematics</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 two-year postdoctoral position is available at the Oxford Centre for Collaborative Applied Mathematics (OCCAM) to work with myself on the mechanical and geometrical analysis of filament assemblies with application to biological systems. Details and Further Particulars can be found at
</p>
<p>
<a href="https://www.maths.ox.ac.uk/node/11748">https://www.maths.ox.ac.uk/node/11748</a>
</p>
<p>
I am particularly interested in candidates with a solid background in solid mechanics and applied mathematics. The successful candidate will join a well-funded and dynamic research centre at the University of Oxford in Applied Mathematics.
</p>
<p>
</p>
</div></div></div>Wed, 17 Feb 2010 07:02:59 +0000goriely7607 at https://imechanica.orghttps://imechanica.org/node/7607#commentshttps://imechanica.org/crss/node/7607Spur gear geometry
https://imechanica.org/node/5517
<div class="field field-name-body field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"><p>
Hi,
</p>
<p>
</p>
<p>
I am a PhD student at Brunel University conducting my research on the noise and vibration attributed to spur gears in contact. I would like to ask for help from anyone who is an expert on gears for their opinion or direction in terms of reading material or thoughts on the limitations and design constraints of spur gear geometry.
</p>
<p>
</p>
<p>
Ideally, All I am looking for is a book or refernce I can read to find out what are the limiting conditions when designing spur gear geometry, eg. The module of the gears in relation to the pressure angle and also the centre distance in relation to pressure angle. I have a lot of literature on spur gear geometry so that is not what I am looking form, rather any literature specifically identifying the limits of spur gear design parameters. HopeI am making sense to everyone.Any help on this topic is very much appreciated! Thank you in advance!
</p>
<p>
</p>
<p>
Kind regards,
</p>
<p>
</p>
<p>
Raul
</p>
</div></div></div><div class="field field-name-taxonomy-forums field-type-taxonomy-term-reference field-label-above"><div class="field-label">Forums: </div><div class="field-items"><div class="field-item even"><a href="/forum/109">Ask iMechanica</a></div></div></div><div class="field field-name-taxonomy-vocabulary-8 field-type-taxonomy-term-reference field-label-above"><div class="field-label">Free Tags: </div><div class="field-items"><div class="field-item even"><a href="/taxonomy/term/2099">Geometry</a></div><div class="field-item odd"><a href="/taxonomy/term/3935">gear</a></div><div class="field-item even"><a href="/taxonomy/term/3936">gears</a></div><div class="field-item odd"><a href="/taxonomy/term/3937">spur</a></div></div></div>Tue, 26 May 2009 10:55:28 +0000raul_bobby5517 at https://imechanica.orghttps://imechanica.org/node/5517#commentshttps://imechanica.org/crss/node/5517How to know the line/node/keypoint number in ANSYS
https://imechanica.org/node/2932
<div class="field field-name-body field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"><p>
Hi,
</p>
<p>
I need to do the modelling in a command file instead of through the ANSYS graphinc interface as I need to try out different configurations and automatically run it in ANSYS. My question is:
</p>
<p>
Say I create a rectangular geometry using the BLC4 command:
</p>
<p>
BLC4,-5,-15,80,100
</p>
<p>
I need to load the structure using the DL command? How do I know which side of the rectangel is assigned which line number? Can I control this? Is it consistent?
</p>
<p>
Thanks,
</p>
<p>
Prakash Manandhar<br /><a href="http://p-manandhar.info">http://p-manandhar.info </a>
</p>
</div></div></div><div class="field field-name-taxonomy-forums field-type-taxonomy-term-reference field-label-above"><div class="field-label">Forums: </div><div class="field-items"><div class="field-item even"><a href="/forum/109">Ask iMechanica</a></div></div></div><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/962">software</a></div></div></div><div class="field field-name-taxonomy-vocabulary-8 field-type-taxonomy-term-reference field-label-above"><div class="field-label">Free Tags: </div><div class="field-items"><div class="field-item even"><a href="/taxonomy/term/1303">ansys</a></div><div class="field-item odd"><a href="/taxonomy/term/2099">Geometry</a></div></div></div>Wed, 26 Mar 2008 17:05:24 +0000jsaaymi2932 at https://imechanica.orghttps://imechanica.org/node/2932#commentshttps://imechanica.org/crss/node/2932