Zhiyan Wei's blog
https://imechanica.org/blog/8594
enFinal presentation
https://imechanica.org/node/5505
<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/527">ES 241</a></div><div class="field-item odd"><a href="/taxonomy/term/529">Advanced Elasticity</a></div><div class="field-item even"><a href="/taxonomy/term/2533">slides</a></div><div class="field-item odd"><a href="/taxonomy/term/3366">Spring 2009</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>Attached is my final presentation.</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="Office presentation icon" title="application/vnd.ms-powerpoint" src="/modules/file/icons/x-office-presentation.png" /> <a href="https://imechanica.org/files/Summary-Zhiyan.ppt" type="application/vnd.ms-powerpoint; length=1107968" title="Summary-Zhiyan.ppt">Summary-Zhiyan.ppt</a></span></td><td>1.06 MB</td> </tr>
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</div></div></div>Mon, 25 May 2009 03:54:20 +0000Zhiyan Wei5505 at https://imechanica.orghttps://imechanica.org/node/5505#commentshttps://imechanica.org/crss/node/5505Abaqus project
https://imechanica.org/node/4290
<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/179">solid mechanics</a></div><div class="field-item odd"><a href="/taxonomy/term/307">project</a></div><div class="field-item even"><a href="/taxonomy/term/2739">Fall 2008</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><span>Project Description</span></strong><span>:</span>
</p>
<p>
<span>Deformation of thin plates (films) driven by eigenstrain. </span><span>Different from conventional deformation driven by applied force, in this project, no external force is applied</span><span>. For convenience, we only consider the eigenstrain caused by thermal expansion. Therefore, stress and strain throughout the field are all from the non-uniform thermal effect. One reason to consider thermal effect is that it is convenient to prescribe temperature field in Abaqus. Another is that the idea is universal since we can map thermal expansion to a wide range of other eigenstrains.</span><span> </span>
</p>
<p>
<strong><span>Why is this problem interesting to me</span></strong><span>:</span>
</p>
<p>
<span>First, eigenstrains caused by thermal effect requires attention in industrial issues. Engineers would never casually neglect the thermal stress in MEMS. As we may all know, thermal stress is a big issue when it comes to packing CPUs and physical memories of computers. As these components work, heat always accompanies. If you have ever used a software to measure the temperature of CPU in summer before, you may find it is not unrare that the temperature reaches 55 degrees centigrade or even higher. Such a difference from the room temperature might arouse a harmful tension or compression inside the highly integrated chip. Therefore, how to eliminate or minimize the negative effect brought by thermal effect becomes a meaningful task. Of course, nowadays, people have brought the negative effect well under control for this kind of problem. I just want to use this project to build up some concrete impression about thermal eigenstrain.</span><span>Another and maybe more important reason why I choose this project is that although I only consider the thermal strain here, it is really not restricted to the thermal strain. For example, liquid crystal elastomer can undertake large thermal deformation. The same magnitude can be obtained by exposing the sample to a proper polarized light, which means thermal eigenstrain can be mapped to light-induced eigenstrain. Similarly, as so much work has shown, the buckling effect in ribbon growth can be also understood by introducing growth rate eigenstrain.</span><span> </span>
</p>
<p>
<strong><span>Plan for this project:</span></strong>
</p>
<p>
<span>Basically I will consider an elliptical thin plate as a start in my project, by varying <em>a</em> and <em>b</em>, I can approximate several different geometries.<span> </span>And then check that how different shapes influence the deformation mode. I also expect to see the result with different thicknesses. Eigenstrain will be mainly applied within the plane. If necessarily, that along the thickness direction will also be tried.</span><span> </span>
</p>
<p>
<strong><span>References: </span></strong>
</p>
<p>
<span>[1] Mansfield, Bending, buckling and curling of a heated thin plate, <em>Proc. R. Soc. A,</em> 268, 316-327, 1962</span>
</p>
<p>
[2]<span> Warner, M. and <span>L. Mahadevan, </span></span><span class="style21"><span>Photo-induced deformation of beams, plates and films, </span></span><em><span>Physical Review Letters</span></em><span>, 92, 134302, 2004</span>
</p>
<p class="MsoNormal">
[3] some work subjected to publication in our group
</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>
<tbody>
<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/eigenstrain_presentation.pdf" type="application/pdf; length=719228" title="eigenstrain_presentation.pdf">eigenstrain_presentation.pdf</a></span></td><td>702.37 KB</td> </tr>
<tr class="even"><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/ES240_Project_Report.pdf" type="application/pdf; length=1062271" title="ES240_Project_Report.pdf">ES240_Project_Report.pdf</a></span></td><td>1.01 MB</td> </tr>
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</table>
</div></div></div>Wed, 12 Nov 2008 05:04:30 +0000Zhiyan Wei4290 at https://imechanica.orghttps://imechanica.org/node/4290#commentshttps://imechanica.org/crss/node/4290Recommendation of Textbooks
https://imechanica.org/node/4122
<div class="field field-name-body field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"><p>Partial Differential Equations in Mechanics: The Biharmonic Equation, Poisson's Equation</p>
<p>A. P. S. Selvadurai</p>
<p>Springer, 2000</p>
<p>ISBN 3540672842, 9783540672845</p>
<p>698 p</p>
<p>
There is a free copy of part of this book online. One can serch it.
</p>
<p>
In this book there are lots of wonderful examples in solid mechanics that can be solved by using "dark-age" method. One can learn both basic concepts and mathematical skills from this book. And one can also use it as a reference book.
</p>
<p>
Abstract of this book
</p>
<p>This two-volume work mainly addresses undergraduate and gra- duate students in the engineering sciences and applied ma- thematics. Hence it focuses on partial differential equati- ons with a strong emphasis on illustrating important appli- cations in mechanics. The presentation considers the general derivation of partial differential equations and the formu- lation of consistent boundary and initial conditions requi- red to develop well-posed mathematical statements of pro- blems in mechanics. The worked examples within the text and problem sets at the end of each chapter highlight enginee- ring applications. The mathematical developments include a complete discussion of uniqueness theorems and, where rele- vant, a discussion of maximum and miniumum principles. The primary aim of these volumes is to guide the student to pose and model engineering problems, in a mathematically correct manner, within the context of the theory of partial differential equations in mechanics.</p>
</div></div></div>Wed, 22 Oct 2008 21:48:24 +0000Zhiyan Wei4122 at https://imechanica.orghttps://imechanica.org/node/4122#commentshttps://imechanica.org/crss/node/4122Self Introduction -- Zhiyan Wei
https://imechanica.org/node/3993
<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/157">students</a></div><div class="field-item odd"><a href="/taxonomy/term/176">ES 240</a></div><div class="field-item even"><a href="/taxonomy/term/179">solid mechanics</a></div><div class="field-item odd"><a href="/taxonomy/term/2739">Fall 2008</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>
Prior Courses in Solid Mechanics:
</p>
<p>
Elasticity, Strength of Material, Plasticity, Theoretical Mechanics, Advanced Solid Mechanics, Computational Mechanics
</p>
<p>
Undergraduate Major:
</p>
<p>
Theoretical and Applied Mechanics
</p>
<p>
Strength Related to This Course:
</p>
<p>
I have already known some basic theories in elasticity and plasticity, so I guess it might be a little easier for me to understand the theoretical part taught in this course.
</p>
<p>
Weakness Related to This Course:
</p>
<p>
In previous study, I always overemphasized the mathematical skills to solve a problem and neglected some deep thinking about the physical meaning. The corresponding result is that I can solve a certain number of easy elastic problems, but I dont have a very clear physical view before I solve them.... Some people have a strong physical intuition and can guess the result even before they solve the problem. I guess they can see through the physical meaning, which I cannot...
</p>
<p>
Another weakness: I know little about finite element simulation, although I took some courses in this field before. Since I didn't try to solve a practical problem using finite element method, I cannot say I really understand it....
</p>
<p>
Research Group:
</p>
<p>
I am currently in Prof. Mahadevan's group. See web page <a href="http://www.seas.harvard.edu/softmat/">http://www.seas.harvard.edu/softmat/</a>
</p>
<p>
Likely Research Direction:
</p>
<p>
To explore the connectivity between the micro-structure and macro-mechanical behavior of amophorous solids.
</p>
<p>
Benifits of Learning This Course:
</p>
<p>
To my research:
</p>
<p>
Either to understand the nature of mechnical behavior or to make a prediction for mechnical behavior in engineering problems requires me to master some basic tools and principles in this field. This course provides me with a good opportunity to learn basic concepts, general ways to deal with a problem in solid mechanics.
</p>
<p>
To my education:
</p>
<p>
I don't want to restrict myself in the area of solid mechanics. My ambisious goal is to understand the general mechanical behavior in nature. Maybe in the end, I won't be an expert in any area, but it is always happy to understand more. Taking solid mechanics is an important and happy start for my future exploration. Prof. Suo definitely brings an impact to my congition to solid mechanics.... I find my opinions about solid mechnics is completely outdated....
</p>
</div></div></div>Mon, 06 Oct 2008 16:49:36 +0000Zhiyan Wei3993 at https://imechanica.orghttps://imechanica.org/node/3993#commentshttps://imechanica.org/crss/node/3993