iMechanica

At the invitation of David Clarke on behalf of the UCSB/Los Alamos Institute of Multiscale Materials and Structures, I gave the following three lectures:

1. Large deformation and instability in dielectric elastomers
2. Large deformation and instability in swelling polymeric gels
3. Mechanics and electrochemistry of polyelectrolyte gels

The abstracts follow, and the slides are attached at the end of this post.

Here is a position for University lecturership in Engineering Science(Solid or Structural Mechanics)in association with a Tutorial fellowshiip at Pembroke College. 

Im trying to model a rotating uniform beam for 12 rotational speeds in Abaqus using c3d20 elements. As expected, "step 1 to step 5" the frequencies increase as the rotational speed is increased. However, for some strange reason, the frequencies stop varying from the fifth speed. I do get warning messages when running the input file but i cant intepret them well since Im new to Abaqus.

I believe the problem is elementary but i cant figure it out. Can anyone review or run the attached input file to let me know what I  am not doing or what exactly is wrong.

Many thanks.

5 Lectureships and 5 Post-Doctoral Research Fellowships in the EPSRC funded national Centre for Advanced Tribology at Southampton (nCATS) 

Lectureships: £32,795 to £41,545

People sometimes complain that reading iMechanica takes time.  This is because iMechanica has a large number of pages, and new pages are added frequently.  If you go directly to iMechanica, you have to load individual pages one by one.  

Scaling of fracture strength, fracture energy and toughness is an important issue when it comes to predicting the behaviour of large-scale structures on the basis of laboratory scale measurements. Historically the work of Leonardo da Vinci and Gallileo is well known, followed by the statistical weakest link theory derived by Weibull in 1939. Weibull scaling is a statistical approach assuming instantaneous failure when the weakest link in a material structure fails.

In honor of its two recent National Medal of Science recipients, Jan Achenbach and Tobin Marks, Northwestern University held a National Medal of Science Symposium on May 14.

Achenbach and Marks received their medals at a White House ceremony in July 2007. The medal honors individuals for “pioneering scientific research in a range of fields, including physical, biological, mathematical, social, behavioral and engineering sciences, that enhances our understanding of the world and leads to innovations and technologies that give the United States its global economic edge.”

In Singapore, I have seen students who lost their relatives in last earthquake. I am very sorry about this, but I think there should be lessons for us in such disasters.  Is'nt any cheap and easy way to reinforce building in the face of earthquakes? I hope such disasters make researchers concentrate on such important topics.

Hey all, I'm looking for a method of determining creep properties of polymer products that is faster than applying a stress to them for an extended period of time.  Is anyone aware of any relations between more quickly/easily attainable material properties and creep properties?  Or is there any way to simulate an extended life test in a shorter amount of time?

Thanks for you help,

wharju2@uiuc.edu

I encounter a big challenge now.

I wanna use mohr-coulomb criterion to simulate the indentation of BMGs in ABAQUS.However, there are many parameters confusing me.

We know the  mohr-coulomb can be written as:

                            τc=k0-ασn

where τc is the shear stress on the slip plane at yielding, k0 and α are constans and σn is the stress component in the direciton normal to the slip plane.

First excuse me for my poor English. Wikipedia-Style Open publish (suggested by Mike Ciavarella) can be a logical solution for many of Current publication and evaluation system problems, currently we utilize popularity for “quality warranty” and “Ranking” of papers and authors. Such factor can be a measure for evaluating the papers and authors in the new style too. The reliability of papers can even increase by this way more, Categorization of scientific papers is one of necessities of today’s scientific network.

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Building on the previous series of Auxetics Workshops and
the 1st International Conference in Exeter (2006), the 2nd
International Conference on Auxetics and Related Systems will discuss
the following topics:

Science 320, 507 (2008)
Stretchable and Foldable Silicon Integrated Circuits
Dae-Hyeong Kim, Jong-Hyun Ahn, Won Mook Choi, Hoon-Sik Kim, Jizhou Song, Yonggang Huang, Zhuangjian Liu, Chun Lu, and John A. Rogers

Recentl, in my research ,I need measure the deformation in the soil caused by the simulation of tunnelling construction in the labotory.In China, I have not found the proper devices to get the deformation occured under the simulation soil surface.Anyone who knows the devices or give me the advice will be appreciated!

An immediate opening for a Ph.D. student in Solid/Structural Mechanics is available at Swinburne University of Technology, Melbourne, Australia. The successful candidate will work with Prof. John Beynon, Prof. Guoxing Lu and Dr. Tracy D. Ruan to investigate the structural components made of aluminium and/or with metallic foams, with enhanced crashworthiness performance under several typical static and impact loadings.   (*Please note that IELTS score is a MUST for this position.*)

After I put down the phone, my heart never felt so heavy. I just called my parents in my hometown, Chengdu,  a city with 12 million people, which is just 90 kilometers away from the center of the strong earthquake at a magnitude of 7.9.  It has killed more than 10,000 people so far. The death toll is still rising hour by hour.

Fig. 1 Earthquake map by the United States Geological Survey

The number of registered users of iMechanica reaches 7000 on 11 May 2008. So far, our fellow iMechanicians have contributed 3172 posts and 7425 comments.  The evolving statistics of iMechanica
(see the latest updates here and here) shows a steady growth with no sign of slowing down. 

Check out the earlier milestones of iMechanica when the number of registered users reached:

6000

How to caculate stress? thanks

I am confused about apply BC of a model in abaqus. because I find that if I apply the accelaration of earthquake on BC, I must remove the fixed constraints applied on BC in previous step in abaqus. so the model become a free body without any constraints.

 any expert can give me some detailed suggestions?thank you very much!^_^

In the attached paper (accepted for publication), we present enriched FE formulations to impose Bloch-periodic boundary conditions. Bloch-periodic BCs arise in the description of wave-like phenomena in periodic media: periodic composites, Schrodinger equation in quantum mechanics, photonic band-gap materials, etc. For a perspective, see the J-Club on elastodynamic bandgaps and metamaterials that was organized by Biswajit Banerjee

 in B. D. Reddy (ed.). IUTAM Symposium on Theoretical, Modelling, and Computational Aspects of Inelastic Media, 99-105. Springer Science, 2008.