iMechanica - Biological Growth
https://imechanica.org/taxonomy/term/10998
enMorphomechanics of growing curled petals and leaves
https://imechanica.org/node/27138
<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/10998">Biological Growth</a></div><div class="field-item odd"><a href="/taxonomy/term/8163">morphoelasticity</a></div><div class="field-item even"><a href="/taxonomy/term/219">wrinkling</a></div><div class="field-item odd"><a href="/taxonomy/term/271">morphogenesis</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>Petals and leaves are usually curled and exhibit intriguing morphology evolution upon growth, which contributes to their important biological functions. To understand the underlying morphoelastic mechanism and to determine the crucial factors that govern the growth-induced instability patterning in curved petals and leaves, we develop an active thin shell model that can describe variable curvatures and spontaneous growth, within the framework of general differential geometry based on curvilinear coordinates and hyperelastic deformation theory. Analytical solutions of distinguished growing shapes such as saddle surface and cylindrical mode are then derived. We reveal distinct morphological evolutions of doubly curved leaves/petals with different curvatures kx (along the main vein) and ky (perpendicular to the main vein) upon differential growth. Compared to the flat (zero curvature) configuration, leaves/petals with longitudinal curvature kx experience a global bending deformation. With the increase of growth strain, the leaf/petal undergoes a coupling behavior of edge wrinkling and global bending deformation, associated with a pitchfork bifurcation. Conversely, the transverse curvature ky does not lead to significant bending behavior, but results in delayed critical buckling threshold and reduced wrinkling amplitude. Physical insights into curvature effects on morphology evolutions are further provided by the analysis of nonlinear competition between bending and membrane energies. Moreover, we explore the effect of vein constraint on pattern formation, showing that, unlike the edge wrinkling observed in leaves with strong vein constraint, those with weak vein constraint are prone to grow into a saddle shape, consistent with analytical solutions. The results uncover the intricate interplay between configurational curvature and vein confinement on plant morphogenesis, providing fundamental insights into a variety of growing shapes of curled petals and leaves.</p>
<p>Ting Wang, Chenbo Fu, Michel Potier-Ferry, Fan Xu*</p>
<p><strong>J. Mech. Phys. Solids</strong>, 184, 105534, 2024. <a href="http://doi.org/10.1016/j.jmps.2023.105534">http://doi.org/10.1016/j.jmps.2023.105534</a></p>
</div></div></div>Tue, 12 Mar 2024 01:45:45 +0000Fan Xu27138 at https://imechanica.orghttps://imechanica.org/node/27138#commentshttps://imechanica.org/crss/node/27138Numerics of growth-induced deformations
https://imechanica.org/node/24836
<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/10998">Biological Growth</a></div><div class="field-item odd"><a href="/taxonomy/term/8163">morphoelasticity</a></div><div class="field-item even"><a href="/taxonomy/term/271">morphogenesis</a></div><div class="field-item odd"><a href="/taxonomy/term/8827">mechanics of morphogenesis</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><img src="https://pbs.twimg.com/media/EqAdR-IW4AA-8Yd?format=jpg&name=large" alt="" width="279" height="203" /><img src="https://pbs.twimg.com/media/EqAdusgXYAghBCH?format=jpg&name=4096x4096" alt="" width="308" height="196" /></p>
<p>Dear iMechanicians,</p>
<p>Growth-induced deformation or morphoelasticity is an interesting phenomenon ranging from living tissues to biological plants in nature. We recently publish a paper in JMPS that solves some challenging boundary value problems by addressing few key issues in computational morphoelasticity. It might be interesting for you. </p>
<p>PDF : <a class="css-4rbku5 css-18t94o4 css-901oao css-16my406 r-1n1174f r-1loqt21 r-1qd0xha r-ad9z0x r-bcqeeo r-1ny4l3l r-1ddef8g r-qvutc0" dir="ltr" href="https://t.co/I35Qe5uMvM?amp=1" target="_blank" rel="noopener noreferrer" data-focusable="true">authors.elsevier.com/a/1cKSi57Zjx1mN</a></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://imechanica.org/files/JMPS2021.pdf" type="application/pdf; length=5108521" title="JMPS2021.pdf">computational morphoelasticity</a></span></td><td>4.87 MB</td> </tr>
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</div></div></div>Wed, 30 Dec 2020 18:01:45 +0000mokarram7624836 at https://imechanica.orghttps://imechanica.org/node/24836#commentshttps://imechanica.org/crss/node/24836Water Affects Morphogenesis of Growing Aquatic Plant Leaves
https://imechanica.org/node/23955
<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/271">morphogenesis</a></div><div class="field-item odd"><a href="/taxonomy/term/19">biomechanics</a></div><div class="field-item even"><a href="/taxonomy/term/10998">Biological Growth</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><img src="http://homepage.fudan.edu.cn/fanxu/files/2020/01/PRL_Cover.png" width="281" height="357" /></p>
<p><span>Lotus leaves floating on water usually experience short-wavelength edge wrinkling that decays toward the center, while the leaves growing above water normally morph into a global bending cone shape with long rippled waves near the edge. Observations suggest that the underlying water (liquid substrate) significantly affects the morphogenesis of leaves. To understand the biophysical mechanism under such phenomena, we develop mathematical models that can effectively account for inhomogeneous differential growth of floating and freestanding leaves to quantitatively predict formation and evolution of their morphology. We find, both theoretically and experimentally, that the short-wavelength buckled configuration is energetically favorable for growing membranes lying on liquid, while the global buckling shape is more preferable for suspended ones. Other influencing factors such as the stem or vein, heterogeneity, and dimension are also investigated. Our results provide a fundamental insight into a variety of plant morphogenesis affected by water foundation and suggest that such surface instabilities can be harnessed for morphology control of biomimetic deployable structures using substrate or edge actuation.</span></p>
<p><span><strong>Phys. Rev. Lett.</strong>, 124, 038003, 2020. <a href="http://dx.doi.org/10.1103/PhysRevLett.124.038003">http://dx.doi.org/10.1103/PhysRevLett.124.038003</a></span></p>
<p><span>This work has been selected for a Focus (</span><a href="https://physics.aps.org/articles/v13/8">Explaining the Ruffles of Lotus Leaves</a><span>) in </span><a href="https://physics.aps.org/articles/v13/8">Physics</a><span>, highlighted by </span><a href="https://www.nature.com/articles/d41586-020-00189-z">Nature</a><span> (</span><a href="https://www.nature.com/articles/d41586-020-00189-z">Rubber ‘leaves’ reveal the physics of the floating lotus</a><span>), featured in <a href="http://physicsbuzz.physicscentral.com/2020/01/how-water-can-shape-lotus-leaves.html">Physics Buzz</a> (<a href="http://physicsbuzz.physicscentral.com/2020/01/how-water-can-shape-lotus-leaves.html">How water can shape lotus leaves</a></span><span>) and </span><a href="https://phys.org/news/2020-01-mathematical-lotus-leaf.html">PhysOrg</a> (<a href="https://phys.org/news/2020-01-mathematical-lotus-leaf.html">Improved mathematical model helps explain different lotus leaf types</a>)<span>.</span></p>
</div></div></div>Thu, 30 Jan 2020 17:20:38 +0000Fan Xu23955 at https://imechanica.orghttps://imechanica.org/node/23955#commentshttps://imechanica.org/crss/node/23955Fully-funded PhD position in Computational Mechanics [#1] for EU students for September 2016, University of Southampton, UK
https://imechanica.org/node/19518
<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/4840">applied mathematics</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/6684">finite element techniques</a></div><div class="field-item odd"><a href="/taxonomy/term/549">continuum mechanics</a></div><div class="field-item even"><a href="/taxonomy/term/19">biomechanics</a></div><div class="field-item odd"><a href="/taxonomy/term/3268">Solver</a></div><div class="field-item even"><a href="/taxonomy/term/10997">Asymptotic</a></div><div class="field-item odd"><a href="/taxonomy/term/3331">surface instability</a></div><div class="field-item even"><a href="/taxonomy/term/219">wrinkling</a></div><div class="field-item odd"><a href="/taxonomy/term/5904">skin</a></div><div class="field-item even"><a href="/taxonomy/term/10998">Biological Growth</a></div><div class="field-item odd"><a href="/taxonomy/term/3284">programming</a></div><div class="field-item even"><a href="/taxonomy/term/5864">gpu</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><strong>PhD project 1 (</strong><strong>Reference:</strong> NGCM-0011)</p>
<p> </p>
<p><span><strong>Generalised asymptotic numerical methods for buckling instability problems in biological systems and bio-inspired morphing structures<br /></strong></span></p>
<p><span>Biotribology Group, nCATS<br /></span>Faculty of Engineering and the Environment<br />University of Southampton, United Kingdom</p>
<p> </p>
<p><strong>Background</strong></p>
<p><span>Buckling instabilities in biological systems play a critical role in biophysical processes such as morphogenesis, growth, ageing and mechanobiological adaptation and it is therefore essential to have access to robust numerical tools (particularly those based on the finite element method) which can be used to elucidate some (bio)physical aspects of these instabilities.</span></p>
<p><span>As humans age, their skin undergoes a series of natural biophysical alterations which occur in combination with the effects of external environmental factors. During this process, the formation and evolution of wrinkles alter the physical properties of the skin surface. Unveiling the underlying mechanical principles that condition the morphologies and patterns of wrinkles are therefore essential in predicting how an aged skin interacts with its environment.</span></p>
<p><span>Similar instabilities also arise in electroactive soft morphing surfaces which is a very hot engineering topic at the moment with a wide range of applications in space, air, on land and underwater.</span></p>
<p><span>From the view point of physics, buckling instabilities are the result of a complex interplay between material and structural properties, boundary and loading conditions, the exact nature of which remains to be elucidated.</span></p>
<p> </p>
<p><strong>The project</strong></p>
<p><span>Current available numerical tools are not robust enough to handle these highly non-linear phenomena in an automatic and systematic way for materials of arbitrary complexity/physics. It is proposed to develop a robust hybrid symbolic-numerical environment based on Mathematica® and highly optimised code (C/Fortran) to enable the simulation of highly non-linear phenomena such as post-buckling arising in a wide range of surface instabilities. The method makes use of a typical finite element discretisation and the principle is to follow the non-linear solution branch by applying a perturbation technique in a stepwise manner. The solution can be represented by a succession of local Padé approximations of high order (typically 20). This offers significant advantages over traditional predictor-corrector methods such as the Newton-Raphson method: robustness, full automation, computing time. Alternative approximation methods of the solution branch will be explored and the implementation of fast asymptotic numerical solvers on GPU architecture will be essential for the project. Multiphysics isogeometric structural and solid finite elements will also be extended/developed to study biological differential growth phenomena and the formation of ageing skin wrinkles.</span></p>
<p> </p>
<p><strong><span>General information</span></strong></p>
<p><strong><span>The position is open to EU students only but exceptional overseas students could be considered.</span></strong></p>
<p>The successful candidate will work in a stimulating research environment, supported by world-leading organisations such as Procter & Gamble, Rolls Royce and the US Air Force and will be encouraged to work with our international academic and industrial collaborators in Europe, South Africa, New Zealand, Singapore and the USA.</p>
<p><span>If you wish to discuss any details of the project informally, please contact Prof. Georges Limbert, nCATS and Bioengineering research group, Email: <a href="mailto:g.limbert@soton.ac.uk">g.limbert@soton.ac.uk</a>, Tel: +44 (0) 2380 592381.</span></p>
<p><span>This project is run through participation in the EPSRC Centre for Doctoral Training in Next Generation Computational Modelling (</span><a href="http://ngcm.soton.ac.uk">http://ngcm.soton.ac.uk</a><span>). For details of our 4 Year PhD programme, please visit </span><a href="http://www.ngcm.soton.ac.uk/programme/index.html">http://www.ngcm.soton.ac.uk/programme/index.html</a></p>
<p> </p>
<p><strong>Apply NOW (for a start in September 2016):</strong></p>
<p> Visit <a href="http://www.ngcm.soton.ac.uk/apply.html">http://www.ngcm.soton.ac.uk/apply.html</a></p>
<p> </p>
</div></div></div>Tue, 23 Feb 2016 10:36:22 +0000Georges Limbert19518 at https://imechanica.orghttps://imechanica.org/node/19518#commentshttps://imechanica.org/crss/node/19518Error | iMechanica