Douglas P Holmes's picture

Journal Club Theme of February 2012: Elastic Instabilities for Form and Function

Welcome to February 2012's Journal club, which will include a discussion on elastic instabilities for form and function. Not long ago, the loss of structural stability through buckling generally referred to failure and disaster. It was a phenomenon to be designed around, and rarely did it provide functionality*. The increasing focus on soft materials, from rubbers and gels to biological tissues, encouraged scientists to revisit the role of elastic instabilities in the world around us and inspired their utilization in advanced materials. Now the field of elastic instabilities, or extreme mechanics, brings together the disciplines of physics, mechanics, mathematics, biology, and materials science to extend our understanding of structural instabilities for both form and function. In this journal club, we're going to look at research on the wrinkling, crumpling, and snapping of soft or slender structures. 


Post-doctoral Position in the Ohio State University

Post-doctoral position is available in the area of ultrasonic material characterization and nondestructive evaluation (strong background and experience in ultrasonic experiment and modeling are required). The position is supported from research grants. The focus area is ultrasonic study of nonhomogenous materials like polycrystalline materials, composites and adhesive bonds. State of the art ultrasonic laboratories and other characterization facilities are available. More details will be provided to interested individuals.

Interested candidates should contact


Jianliang Xiao's picture

ASME IMECE 2012, “Mechanics of Adhesion” symposium


Adhesion has long been an important issue for mechanics and
many other disciplines. Its influence spans macro-, micro-, nano- and molecular
scales. When size goes down, adhesion plays a more and more significant role.
Many important technologies attribute to adhesion, such as transfer printing
for advanced microfabrication, super adhesives inspired by gecko foot hairs,
and self-assembly. Adhesion also has strong implications on the behavior of
nanomaterials (such as nanotubes and graphenes) and biological systems (such as
cells). This minisymposium "Mechanics of Adhesion" is to provide a


POST DOCTORAL POSITIONS

One (1) to Two(2) years post-doctoral positions are open in Ecuador (South America). The following are areas of interest:

  • Robotics,
  • Energy,
  • Fracture,
  • CFD,
  • Nano-technology,
  • Bio-mechanics,
  • Mathematics (PDE-FEM)

The candidate should hold a PhD degree related to the area of application, and should have the motivation to do research and open new research lines. Teaching is also an important component.


Call for Paper for a Special Issue of Mechanical Systems and Signal Processing - Submission deadline 30 June 2012

Special Issue on Instantaneous Angular Speed (IAS) processing and angular applications
For more information, visit the journal homepage:  http://www.journals.elsevier.com/mechanical-systems-and-signal-processing/


Can equations of equilibrium predict all physical equilibria? A case study from Field Dislocation Mechanics

Amit Das, Amit Acharya, Johannes Zimmer, Karsten Matthies

 


Postdoctoral positions in statistical modeling of fracture and plasticity

We anticipate the opening of four postdoctoral positions in 2012 to work on statistical aspects of fracture and plasticity,  and in particular on size effects in the fracture of  disordered media and in microplasticity.  The positions will be funded by the ERC Advanced Grant 2011, SIZEFFECTS.

We look for candidates with a strong background in one or more of the following areas:
- statistical mechanics (scaling, critical phenomena, disordered systems)
- numerical modeling fracture
- dislocation dynamics simulations
- molecular dynamics simulations of mechanical properties of solids.


Post-doc at the University of Liège : Simulation of micro/nano-structured materials described by 3D tomography

Post-doc at the University of Liège : Simulation of micro/nano-structured materials described by 3D tomography

The tasks involved in this position include geometrical analysis of the
3D images, generation of datasets which are suitable for the computations
(meshes, level-sets fields ...), computations using novel numerical techniques
(X-FEM and related)

More details & contact information at  http://www.cgeo.ulg.ac.be/post-doc.pdf


Alejandro A. Ortiz's picture

THREE MECHANICAL ENGINEERING TENURE-TRACK FACULTY POSITIONS

The University of Chile invites applications for three full time tenure-track faculty positions in Mechanical Engineering. Applicants must have deep interest in undergraduate and graduate teaching, as well as the purpose to conduct long-term, externally funded research programs at international level. Candidates are also expected to maintain fruitful work relationships with industry in their respective areas. According to qualifications, they may be ranked at the Assistant or Associate Professor level.


Candidates are sought in three areas:


Konstantinos I. Tserpes's picture

Strength of graphenes containing randomly dispersed vacancies (new journal paper)

Strength of graphenes containing randomly dispersed vacancies

Tserpes, K.I.


Catalin Pruncu's picture

Deadline extended for NT2F12 congress

Deadline extended for NT2F12 congress which will be held in Transilvania University of BRASOV.

Brasov is one of the largest and most cherished cities of the country. Surrounded on three sides by mountains, it was a perfect place for a medieval settlement.

The old city, founded by the Teutonic Knights in 1211, is one of the best preserved cities in all of Europe. It was thotoughly restored to the delight of an increasing number of tourist. It is the capital city of Brasov Country, in central Romania, in Transylvania, at the foot of the  Carpathian Mountains. Brasov also makes a fabulous base for exploring the surrounding countryside where the air is clean and the people friendly.


Spring stiffness of a helical spring

Once in a while I have to find the stiffness of a spring that I get from the local hardware shop.  I usually use a formula that can be found in some books on mechanics of materials.

But the assumptions bother me a bit because the springs that I used usually underwent large deformations and I wasn't sure whether the numbers I was using were correct or not.  

To check the formula I compared its predicted k to numbers from Abaqus simulations and found reasonably good results for many situations - but not for soft springs.

I've attached a write-up on that that contains a python script to generate the geometry.  Let me know if you find it useful.


Amit Acharya's picture

A mathematician's take on "what is light?"

Attached is an intriguing commentary on the scientific method through an example, written by my good friend, Luc Tartar. The specific example is that of trying to understand what 'light' might be, especially from a mathematician's point of view. The mathematician in this case is an extremely talented one, who also happens to actually understand a whole lot of physics and mechanics.

I am posting it especially for our younger members on imechanica, since I think there are interesting things to learn here. If you are an engineer or a physicist, it will not necessarily be a comfortable read, both on matters technical and philosophical. But my personal point of view is that not everything worth learning has to be within one's comfort zone. Being open-minded about learning, and recognizing when there is something to be learnt, is one of the best habits we can develop. One does not have to agree with all that is said, but the greatest intellectual progress happens when a collection of sincere, talented people operate at the boundary of their individual comfort zones - not necessarily agreeing, but definitely learning from each other.

So, enjoy!

 


ikpuri's picture

Mechanics in space (and High School): Lego Man's balloon voyage, or Lego Man in space

For an interesting news article about the mechanics behind Lego Man's balloon voyage to space, read the Toronto Star article by Mary Ormsby. She writes, "A 1,200-gram weather balloon, the crucial role of gravity, quiver-reducing ropes, Styrofoam’s versatility, burst altitude, a University of Wyoming website and a free software program for shutterbugs were part of the formula Mathew Ho and Asad Muhammad, both 17, used to launch, film and land the patriotic, flag-bearing Lego Man..."


marco.paggi's picture

Fracture and contact mechanics for interface problems: a special issue of EFM

A Special Issue of Engineering Fracture Mechanics

on

"Fracture and contact mechanics for interface problems", edited by Marco Paggi, Alberto Carpinteri and Peter Wriggers has just been published:

http://www.sciencedirect.com/science/journal/00137944/80

The selected articles were presented in a Minisymposium of the IV European Conference on Computational Mechanics, Paris, France, 2010.

 

List of contents


Jiangshui Huang's picture

Giant, voltage-actuated deformation of a dielectric elastomer under dead load

Far greater voltage-actuated deformation is achievable for a dielectric elastomer under equal-biaxial dead load than under rigid constraint usually employed. Areal strains of 488% are demonstrated. The dead load suppresses electric breakdown, enabling the elastomer to survive the snap-through electromechanical instability. The breakdown voltage is found to increase with the voltage ramp rate. A nonlinear model for viscoelastic dielectric elastomers is developed and shown to be consistent with the experimental observations. 


jkyang's picture

Looking for Ph.D. Candidates in Experimental/Computational Mechanics, University of South Carolina

We seek for highly motivated
Ph.D. candidates in the field of 1) Acoustic metamaterials (e.g., phononic


Frictional rolling contact model CONTACT version 12.1 released

Dear all,

Herewith I want to announce the release of the frictional rolling contact model CONTACT version 12.1.

The main changes with respect to earlier versions of the program are as follows:

  • Achieved a 100-fold speedup for solving larger normal contact problems.
  • Improved the documentation of the viscoelastic part of CONTACT and
    provided an example of its use.
  • Distinguished free and premium features in the software, the latter
    requiring a valid license file.

For the full release-notes or more information on the program refer to the website www.kalkersoftware.org.

Regards, Edwin


ikpuri's picture

Mechanics in biology: Elastic properties of an elastomeric protein


Dibakar Datta's picture

Postdoctoral Research Associate at Brown University: Finite Element Simulations of Active Biopolymer Networks

A postdoctoral position with
primary focus on finite element simulations of active biopolymer
networks is available immediately at Shenoy Research Group @ Brown University . We are looking for a strongly
motivated candidate to work on the mechanics of active cytoskeletal
networks. The ideal candidate will have a background in solid
mechanics/computational physics with expertise in finite element simulations. Experience with Monte Carlo methods and stochastic simulations is desired but not essential.  This
individual will have the opportunity to be directly involved in


Call for Abstracts: Asia-Pacific Conference on Engineering Plasticity and Its Application (AEPA 2012), Singapore, 5-7 Dec. 2012

THE 11th ASIA-PACIFIC CONFERENCE ON ENGINEERING PLASTICITY AND ITS APPLICATIONS (AEPA2012) 
(5 - 7 December 2012, Singapore)

    We are pleased to announce that the Eleventh Asia-Pacific Conference on Engineering Plasticity and Its Applications, AEPA2012, will be held in Singapore, in December 2012, following the previous successful symposia in Hong Kong (1992), Beijing (1994), Hiroshima (1996), Seoul (1998), Hong Kong (2000), Sydney (2002), Shanghai (2004), Nagoya (2006), Daejeon (2008) and Wuhan (2010).


Zhigang Suo's picture

A website wholly devoted to buckled shells

John Hutchinson has just pointed out to me the website, shellbuckling.com.  The site is devoted to the mechanics of buckled shells, with downloadable photos, slides, papers, and computer codes.  The site also has a section on buckling people.  The site is created by a veteran buckling person, Dr. David Bushnell, formerly of Lockheed Martin.  Check the site out, and enjoy. 


Bo Li's picture

Experimental study on the dielectric properties of polyacrylate dielectric elastomer

The dielectric constant of elastomeric dielectric material is an
essential physical parameter, whose value may affect the
electromechanical deformation of a dielectric elastomer actuator. Since
the dielectric constant is influenced by several external factors as
reported before, and no certain value has been confirmed to our
knowledge, in the present paper, on the basis of systematical comparison
of recent past literature, we conducted extensive works on the
measurement of dielectric properties of VHB films, involving five
influencing factors: prestretch (both equal and unequal biaxial),
electrical frequency, electrode material, stress relaxation time and
temperature. Experimental results directly show that the dielectric


azadpoor's picture

PhD position on tissue engineering of cartilage and mechanical evaluation of the generated tissue

A vacant four-years PhD position is available. This PhD project will be done in Erasmus Medical Center (Rotterdam, NL) in collaboration with Delft University of Technology (Delft, NL) and is a part of a larger Dutch project on regenerative medicine and tissue engineering. The aim of the project is to generate cartilage from bone marrow derived stem cells in culture and evaluate them with molecular assays (Rotterdam) and mechanical assays (Delft). The culture protocol can be varied with oxygen level, tonicity, and active molecules.


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