iMechanica - Comments for "Engineering Sciences 242r: Fracture Mechanics of Thin Films and Composite Materials"
https://imechanica.org/node/754
Comments for "Engineering Sciences 242r: Fracture Mechanics of Thin Films and Composite Materials"enRecords of a course
https://imechanica.org/comment/12346#comment-12346
<a id="comment-12346"></a>
<p><em>In reply to <a href="https://imechanica.org/comment/12342#comment-12342">Li Han</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>Li Han: I don't recall that the full course was recorded, but some lectures might be. I don't know who has these CDs.</p>
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</ul>Tue, 01 Sep 2009 02:03:37 +0000Zhigang Suocomment 12346 at https://imechanica.orgLi Han
https://imechanica.org/comment/12342#comment-12342
<a id="comment-12342"></a>
<p><em>In reply to <a href="https://imechanica.org/node/754">Engineering Sciences 242r: Fracture Mechanics of Thin Films and Composite Materials</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><span class="Apple-style-span">
<p>Dear Zhigang,</p>
<p> I remember the course has been recorded. I am just wondering who to contact to revisit these valuable materials. Thank you. </p>
<p></p></span>
</p><p>Li Han </p>
<p> </p>
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</ul>Mon, 31 Aug 2009 19:25:57 +0000Li Hancomment 12342 at https://imechanica.orgDistance Education
https://imechanica.org/comment/10928#comment-10928
<a id="comment-10928"></a>
<p><em>In reply to <a href="https://imechanica.org/node/754">Engineering Sciences 242r: Fracture Mechanics of Thin Films and Composite Materials</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">
Distance education open up many possibilities, more and more courses are being available, which I believe benefits both the university and the people, knowledge that before was limited to a few can now be accessed to many.
</p>
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</p><p> <a href="http://www.aptgroup.com/">http://www.aptgroup.com/</a></p>
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</ul>Tue, 26 May 2009 08:05:23 +0000Daniel Anderssoncomment 10928 at https://imechanica.orgMy friends keep talking of
https://imechanica.org/comment/9106#comment-9106
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<p><em>In reply to <a href="https://imechanica.org/comment/1093#comment-1093">Question about COD and CTOD</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>My friends keep talking of COD's and CTOD's and though they learn at the <a href="http://www.edu-cyberpg.com/Directory/IWU-Online.html">Ohio Dominican University</a> they couldn't tell me the difference between the two notions. Thanks for asking and thanks to all of you who answered.</p>
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</ul>Mon, 10 Nov 2008 17:22:50 +0000johannabartleycomment 9106 at https://imechanica.orgComprehensive Distance Education
https://imechanica.org/comment/7107#comment-7107
<a id="comment-7107"></a>
<p><em>In reply to <a href="https://imechanica.org/comment/1066#comment-1066">Education without boundary</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>
That is very interesting idea sir,if imechanica can provide a distance education from all field of engineering mechanics.The whole world is watching all the comments and suggestion in this site. Maybe, We here from asia can be benefited in your great proposal " Education without boundary" reagardless of distance,races,ethnics and culture..
</p>
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</ul>Fri, 11 Apr 2008 13:56:43 +0000Noel M. Dioyancomment 7107 at https://imechanica.orgCOD and CTOD:
https://imechanica.org/comment/3820#comment-3820
<a id="comment-3820"></a>
<p><em>In reply to <a href="https://imechanica.org/node/754">Engineering Sciences 242r: Fracture Mechanics of Thin Films and Composite Materials</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>
To my knowledge, COD is first introduced by Boyle [1962] for measuring cracklength directly (I mean without measuring from microscope readings). This is essentially a strain gage reading for compliance (inverse of stiffness, COD/Load). I thought CTOD is the displacement of the crack tip and is different from COD. All these days, I convinced myself that CTOD is developed for elastoplastic while COD can take care of LEFM area but now confused. I will go through the references cited by Wu. Thanks.
</p>
<p>
Gopinath
</p>
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</ul>Mon, 23 Jul 2007 21:18:48 +0000Gopinath Venkatesancomment 3820 at https://imechanica.orgCOD & CTOD (Reply to Ling Zhu)--Fracture Mechanics class
https://imechanica.org/comment/1130#comment-1130
<a id="comment-1130"></a>
<p><em>In reply to <a href="https://imechanica.org/node/754">Engineering Sciences 242r: Fracture Mechanics of Thin Films and Composite Materials</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">
Dear Ling, COD as a criterion is used for crack growth in elastoplastic materials, for which the K-criterion does not hold due to the finite plastic zone near crack tip. However, within the framework of SSY, COD-criterion is equivalent to K-criterion (Kanninen and Popelar, 1985). COD-criterion is considered as a supplementary fracture criterion for elastoplastic materials before the evaluation of J-integral (A.A. Wells, 1979) to be discussed in this class. The typical definition of CTOD for cracking in ductile materials can be found in the following link: <a href="http://www.efunda.com/formulae/solid_mechanics/fracture_mechanics/fm_epfm_CTOD.cfm">http://www.efunda.com/formulae/solid_mechanics/fracture_mechanics/fm_epfm_CTOD.cfm</a>
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<p class="MsoNormal">
Based on my understanding, COD and CTOD indicate the same term though they may have a little difference in literature here and there. For example, the COD-criterion was discussed in detail in the classic textbook: Advanced Fracture Mechanics (Kanninen and Popelar, 1985), in which the term COD is actually also the CTOD. While in the textbook Cracks and Fracture (Broberg, 1999, pp. 575), it says that COD and COA (crack opening angle) are often written as CTOD (crack tip opening displacement) and CTOA (crack tip opening angle). Also, in some literature, it says that COD is the total displacement at crack tip (usually mixed-mode crack), while CTOD indicates the crack tip opening displacement due to pure mode I loading [e.g. Sha et al., Int. J. Fracture 104 (2000) 409-423]. There may be many others. Therefore, when we use COD or CTOD, we need to take care of the definition used in context. Hope this would make it clear.
</p>
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</ul>Mon, 23 Jul 2007 19:34:02 +0000Xiangfa Wucomment 1130 at https://imechanica.orgQuestion about COD and CTOD
https://imechanica.org/comment/1093#comment-1093
<a id="comment-1093"></a>
<p><em>In reply to <a href="https://imechanica.org/node/754">Engineering Sciences 242r: Fracture Mechanics of Thin Films and Composite Materials</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>Dr. Hutchinson and Suo,I am taking the fracture mechanics class from Lincoln Nebraska now. During my literature reading, I come across two terms :the Crack Opening Displacement (COD) and the Crack Tip Opening Displacement(CTOD). What is the difference between these two terms? Can COD be used as a criterion to predict a crack's propagation? For example, for a given material, can we say the crack will propagate if the opening displacement exceeds a certain value? Appreciate your help.</p>
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</ul>Fri, 09 Feb 2007 19:19:35 +0000zhulingcomment 1093 at https://imechanica.orgTeaching the My Space Generation
https://imechanica.org/comment/1090#comment-1090
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<p><em>In reply to <a href="https://imechanica.org/comment/1087#comment-1087">Good company and motivation</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 could not disagree more with the idea that online teaching is mutually exclusive of "good company and motivation" especially when the students in question have been raised in the time of email, instant messaging, and now web-based social networking forums such as <a href="http://www.myspace.com/">My Space</a>. This is a generation of students who are accustomed to forming relationships online and thus there are no real disadvantages of internet-based teaching. A potential key advantage includes the potential for less frightening participation in online chats or other forms of nontraditional discussion for students who might be too shy to speak up in a traditional classroom setting. </p>
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</ul>Fri, 09 Feb 2007 16:50:09 +0000MichelleLOyencomment 1090 at https://imechanica.orgGood company and motivation
https://imechanica.org/comment/1087#comment-1087
<a id="comment-1087"></a>
<p><em>In reply to <a href="https://imechanica.org/comment/1085#comment-1085">Internet teaching</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>Good company and motivation can hardly be achieved through internet teaching. These are values for on-campus classroom teaching.</p>
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</ul>Fri, 09 Feb 2007 16:09:00 +0000Henry Tancomment 1087 at https://imechanica.orgInternet teaching
https://imechanica.org/comment/1085#comment-1085
<a id="comment-1085"></a>
<p><em>In reply to <a href="https://imechanica.org/comment/1066#comment-1066">Education without boundary</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>Teng--</p>
<p> You raise some good questions. There has been talk of using the internet to enhance teaching for many years, and, while some advances have been made, it is surprizing that the internet has not be more exploited for this purpose. Zhigang and I wanted to see how this collaboration with the University of Nebraska would work--we view this as a noble experiment! Stay tuned. </p>
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</ul>Fri, 09 Feb 2007 15:25:21 +0000John W. Hutchinsoncomment 1085 at https://imechanica.orgInstant discussion is the kernel of iMechanica
https://imechanica.org/comment/1069#comment-1069
<a id="comment-1069"></a>
<p><em>In reply to <a href="https://imechanica.org/node/754">Engineering Sciences 242r: Fracture Mechanics of Thin Films and Composite Materials</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>Instant discussion is the kernel of iMechanica.<br />In the old times without internet, we had books. Students could read the same book; in this sense the education had no boundary even at those old times.<br />However, book readers can not exchange ideas, ask questions. In iMechanics, things are different; we can put our concerns, even stupid ones, on the table.</p>
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</ul>Thu, 08 Feb 2007 22:13:07 +0000Henry Tancomment 1069 at https://imechanica.orgEducation without boundary
https://imechanica.org/comment/1066#comment-1066
<a id="comment-1066"></a>
<p><em>In reply to <a href="https://imechanica.org/node/754">Engineering Sciences 242r: Fracture Mechanics of Thin Films and Composite Materials</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>John and Zhigang: </p>
<p>Interesting idea to offer a course on two campuses at the same time, with the aid of iMechanica. I'm wondering how this works, John teaches at Nebraska and Zhigang teaches at Harvard? </p>
<p><a href="http://en.wikipedia.org/wiki/Distance_education">Distance (Remote) education</a> has a rather long history. Radio, TV, and recently Internet have all been used to deliver the content in distance education. In the age of Web2.0, people have started to talk about <a href="http://en.wikipedia.org/wiki/ELearning_2.0">eLearning 2.0.</a></p>
<p>I'm imagining, with an online platform like iMechanica, plus podcasts of lectures (audio, and even video later on), a mechanics course can be offered for iMechanicians of interest. This concept can be readily adapted to many other disciplines. Detail logistics aside, such a teaching/learning process may have significant impact on our trational education system in the future. Can we get rid of the barrier between universities, and provide education without boundary? </p>
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</ul>Thu, 08 Feb 2007 21:55:38 +0000Teng Licomment 1066 at https://imechanica.orgError | iMechanica