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Xuanhe Zhao's picture

A method to analyze electromechanical stability of dielectric elastomer actuators

      This letter describes a method to analyze electromechanical stability of dielectric elastomer actuators.  We write the free energy of an actuator using stretches and nominal electric displacement as generalized coordinates, and pre-stresses and voltage as control parameters.  When the Hessian of the free-energy function ceases to be positive-definite, the actuator thins down drastically, often resulting in electrical breakdown.  Our calculation shows that stability of the actuator is markedly enhanced by pre-stresses.

Jie-Hua Zhao's picture

Research Position at Texas Instruments (Dallas, Texas)

 
   This is a stress modeling position in TI's research
organization Silicon Technology Development (SiTD). The opening is
immediate and the position is filling very fast. Minimum requirement:
MS degree in the following fields: Mechanical Engineering, Physics,
Materials Science or Engineering Mechanics. PhD degree is preferred. 
Please email your resume to Jie-Hua (Jeff) Zhao at jhzhao@ti.com or
Darvin Edwards at rvin@ti.com. Call Jeff at 972-995-8851 for detail.

Jinxiong Zhou's picture

Propagation of instability in dielectric elastomers

When an electric voltage is applied across the thickness of a thin layer of an dielectric elastomer, the layer reduces its thickness and expands its area. This electrically induced deformation can be rapid and large, and is potentially useful as soft actuators in diverse technologies. Recent experimental and theoretical studies have shown that, when the voltage exceeds some critical value, the homogenous deformation of the layer becomes unstable, and the layer deforms into a mixture of thin and thick regions.

Data relevant to science and engineering education, employment, and research

Anecdotal evidence can often serve as a basis for an opinion on the state of science and engineering in the US and abroad. While that evidence is valuable, it is not necessarily representative of national treends. Fortunately, the US government has collected useful information relevant to education, research, and employment within the science and engineering communities and presented it in a series of annual reports.


Why lionize mathematics in science/engineering?

This has reference to (only) the *last paragraph* in Prof. Harry Lewis' recent post, found at: node/1423#comment-2880.

The reason I write the present post is because I always seem to have had a view of inventing, learning, or teaching mathematics that is remarkably at odds with what Prof. Lewis' last paragraph *seems* to imply.

Cai Wei's picture

Postdoctoral position at Stanford in materials simulations

Postdoctoral positions are available in the Micro and Nano Mechanics group led by Prof. Wei Cai in the Mechanical Engineering Department at Stanford University.  [Link]

On the Possibility of Piezoelectric Nanocomposites without using Piezoelectric Materials

In a piezoelectric material an applied uniform strain can induce an electric polarization (or vice-versa). Crystallographic considerations restrict this technologically important property to non-centrosymmetric systems. It can be shown both mathematically and physically, that a non-uniform strain can potentially break the inversion symmetry and induce polarization even in non-piezoelectric dielectrics.

August Workshop on Materials Characterization for Nanoscale Reliability

We invite you to participate in the upcoming Workshop on Materials Characterization for Nanoscale Reliability, to take place 14-16 August, 2007 at the University of Colorado in Boulder, Colorado. Details are posted at http://www.boulder.nist.gov/div853/Nanoscale_Reliability_workshop/index.htm.

Pradeep Sharma's picture

FEMLAB and strain gradient theories

I am aware of several recent papers related to computational issues in strain gradient and other higher order theories. Has anyone tried the software package FEMLAB for such theories ? It purports to solve user defined PDEs. We have only had limited experience with it and I am curious to find out if someone has tried it out.

UG Course on Solid Mechanics

Given below is a sequence that might properly address the question of what to teach in the first (and the only) UG couse on strength of materials or solid mechanics.

0. Note: It's a mistake to believe that the contents for such a course can be covered in a linear fashion. Apply the spiral theory of knowledge and revisit certain concepts again and again: e.g., the concepts of stress, strain, fields, BV problems, theoretical structure, etc.

1. Introduction:

Zhigang Suo's picture

Google will videotape all Harvard classes and make them universally accessible

I wish that this thought had come to me earlier, so that I could have posted it on April First.  No, I'm unaware of such a program.  Instead, Harvard faculty have just emerged from a multi-year review of curriculum, and reaffirmed the commitment to liberal education, after voting out a president not too long ago.

Rui Huang's picture

Senior Software Engineer Position at LUSAS, London

From Dr. Qizhi Xiao :

We are looking for several new permanent staffs, including software developers with solid background on mechanics and good programming skills. the detailed information about the posts can be found from

http://www.lusas.com/joboffers.html

The following is the information for software developers:

-------------------------------------------------------------------------
LUSAS Senior Software Engineer (Ref SSE-W)

Chris Pearce's picture

Computational Solid Mechanics Summer School: 26 Aug - 1 Sep 2007, Glasgow UK

Mathematical Modelling & Computational Methods in Solid Mechanics

26th August - 1st September 2007

University of Glasgow

Amit Acharya's picture

Does a radially expanding cylinder bend?

 The Koiter-Sanders-Budiansky bending strain measure and a nonlinear generalization

 We know from strength of materials that non-uniform stretching of fibers along the cross section of a beam produces bending moments. But does this situation necessarily correspond to a 'bending' deformation? For that matter, what do we exactly mean kinematically when we talk about a bending deformation?

Warner Tjardus Koiter (1914-1997) and his 1945 thesis

Koiter's PhD thesis, dated 1945, gave the birth of post-buckling analysis, and quantified the notion of imperfection sensitivity.  He wrote the thesis in Dutch.  An excellent English translation is free online.

Taxonomy upgrade extras: 

John Lyell Sanders Jr. (1924-1998)

John Lyell Sanders, Jr., served on the Harvard faculty for a total of thirty seven years and as Gordon McKay Professor of Structural Mechanics for over thirty years from 1964 until his retirement in 1995.  Read the full text of this recently published memorial minute.  

Taxonomy upgrade extras: 
Vlado A. Lubarda's picture

In Memoriam: Erastus H. Lee

Erastus H. LeeErastus H. Lee, professor emeritus and a prominent researcher, with fundamental contributions to plasticity, viscoelasticity and wave propagation, died at the age of 90 on May 17, 2006, in Lee, New Hampshire.

Open Source Software

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Free Tags: 
  • RSS feed for comments on this page: crss/node/1394
  • This page was started following discussions initiated by Mogadalai Gururajan.
         Here are some links to open source codes/software available on the net; all this information is collected from different posts at iMechanica. It is quite possible that we missed some, and some that are listed are not open source. If so, please feel free to edit the post or leave a comment with relevant links so that we can edit the post.

A general discussion on the undergraduate course on Strength of Materials

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Most departments of Mechanical Engineering, Civil Engineering, and Aerospace Engineering have a required course called variably "Strength of Materials", "Introduction to Solid Mechanics", etc.  In most departments, the content of the coure is mainly about static, elastic deformation of rods, shafts, beams and columns.  It might be a good idea to share your thoughts on this course. 

What sort of conferences do you prefer to go to? Conferences that cover a range of topics or those that are specialized?

Range of topics (e.g. McMat07)
41% (13 votes)
Special subset of mechanics (e.g. Plasticity07)
22% (7 votes)
Whatever I can afford
22% (7 votes)
Only if invited to speak
6% (2 votes)
Conferences are a waste of time
9% (3 votes)
Total votes: 32
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Mahdi Kazemzadeh's picture

"Students Turn"

Here is a hot topic" Overlaps in our knowledge structures " on iMechanica for all of the students!! This belongs to how students iMechanica can be developed or how students can improve it! Please read the comments and let the others know your ideas about this developements. You will find some suggestions there also. With all students ideas collected, there will be a solution to improve current situation for students section.

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