Nikhil Sharma's picture

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. The key concept is that all dielectrics (including non-piezoelectric ones) exhibit the aforementioned coupling between strain gradient and polarization-an experimentally verified phenomenon known in some circles as the flexoelectric effect.


Richard Vinci's picture

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.....

The purpose of the workshop is to bring together recognized experts in a wide variety of fields, representing the multidisciplinary nature of nanoscience, to discuss MATERIALS CHARACTERIZATION and MODELING ISSUES of critical importance to ASSESSING and IMPROVING the MECHANICAL RELIABILITY of extremely fine-scale materials. One goal of the workshop is the creation of a roadmap for nanoscale characterization and modeling techniques for the next 5 to 10 years.


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.


Ajit R. Jadhav's picture

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:

The range of (stress/strain/displacement analysis) problems to address.

Qualitative and empirical characterization of materials response under tension, compression, shear, fatigue, creep, impact, etc.


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.

On the other hand, the thought of Google videotaping all Harvard classes may not be so crazy.  Let me quote the mission of Google:

"Google's mission is to organize the world's information and make it universally accessible and useful."


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)


Rashid K. Abu Al-Rub's picture

NSF: 2007 Alan T. Waterman Award Winner

Photo of Peidong Yang, 2007 Alan T. Waterman Award Winner2007 Alan T. Waterman Award Winner

Peidong Yang


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

Registration is now open for a Summer School on Mathematical Modelling & Computational Methods in Solid Mechanics. This week-long event is to take place at Glasgow University, UK, between 26th August and 1st September 2007. The material covered will address both basic and advanced topics within computational solid mechanics. Speakers include Professors Ray Ogden, Nenad Bicanic, Harm Askes, Marc Geers and Gerhard Holzapfel.


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?

To make the question more concrete, consider a cylinder that expands uniformly along all radial rays. Does this deformation of the cylinder correspond to bending? I think it is fair to say that most would say that this is purely a stretching deformation with no bending. But then, what is precisely a bending deformation?


Zhigang Suo's picture

Harvard Task Force Calls for New Focus on Teaching and Not Just Research

The New York Times carried an article the other day, reporting on a document titled "A Compact to Enhance Teaching and Learning at Harvard".  I happened to be at the faculty meeting of the Faculty of Arts and Sciences when the documment was discussed.  I heard eloquent speeches, but couldn't say that I heard anything really innovative.   Many of my colleagues spend much time teaching and find the experience rewarding.  So, what is the problem?


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

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.


John Lyell Sanders Jr. (1924-1998)

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.  


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.

Ras Lee was born on February 2, 1916, in Southport, England. He graduated from Cambridge University in 1937 with a bachelor degree in mechanical sciences and mathematics. After a further year of postgraduate study at Cambridge with Professor C. E. Inglis, Ras was awarded a fellowship from the Commonwealth Fund of New York to study with Professor Stephen Timoshenko at Stanford University. He completed his Ph.D. degree in 1940 and immediately thereafter became involved in the British war efforts during World War II. He worked first as a progress officer in the British Purchasing Commission in New York and later in the British Air Commission in Washington. Officer Lee was concerned with planning aircraft deliveries from U.S. companies and keeping records of modifications required to meet British needs.


Open Source Software

         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

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
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. I can say that page and comments are just for students to say how they like their iMechanica to be. Thank you.


Teng Li's picture

Flexible Macroelectronics (a video for middle/high school students)

This is a winning entry in the Sci/Terp Video Competition at University of Maryland (UMD).


 


Henry Tan's picture

Can iMechanica replace mechanical seminars in the future?

Reading the article, future role of iMechanica (http://imechanica.org/node/908) posted by Teng (http://imechanica.org/user/10), I am thinking that iMechanica may replace mechanical seminars, lectures conducted by invited mechanicians, in the future.

Academic seminars have several functions: first, to exchange information; second, to build up connections.


Mogadalai Gururajan's picture

New category for open source codes

Update: An Open Source Review page has been created. Please feel free to leave links, codes and comments on the page. 

Dear Mechanicians,

I have seen that there is lot of code sharing among the mechanicians at iMechanica; a search for the word "code" for example produces nearly fifty entries, of which, I believe, at least half of the posts are pointers to codes and their sharing.


LECAM's picture

Description of fatigue damage in carbon black filled natural rubber

Description of fatigue damage in carbon black filled natural rubber

The present paper deals with fatigue damage at the macroscopic scale in carbon black filled natural rubber under uniaxial loading conditions. Uniaxial tension-compression, fully relaxing uniaxial tension and non-relaxing uniaxial tension loading conditions were applied until samples failure. Results, summarized in a Haigh diagram, show that only one type of fatigue damage is observed for uniaxial tension-compression and fully relaxing uniaxial tension loading conditions, and that several different types of fatigue damage take place in non-relaxing uniaxial tension loading conditions.


Henry Tan's picture

Overlaps in our knowledge structures

Each one of us developed his own knowledge structure. After graduation we followed different research interests, took different projects, and adopted different approaches, analytical, numerical, or experimental. Therefore the knowledge structure is unique for every person, coming from his/her education background and scientific experiences.

There are several levels for the overlapping in our knowledge structure.


MichelleLOyen's picture

North American Workshop on Applications of the Physics of Porous Media

The 7th North American Workshop on Applications of the Physics of Porous Media will be held in Puerto Vallarta, Mexico, November 2-6, 2007. This will be the 7th biennial meeting of researchers around the world who are interested in the phenomena associated with physics of fluid flow and deformation in porous media and its applications to a broad range of basic roblems encountered in geophysics, geomechanics, medical physics, and condensed matter physics.

Full details are available at the website:


Rashid K. Abu Al-Rub's picture

Strain Gradient Plasticity

Recently, there have been many strain gradient theories that are used for the interpretation of size effect at the micron and submicron length scales. The basic idea of these theories is the introduction of a first, or second (or both) gradients of strain or any internal state variable in the governing equations of classical theories.


Zhigang Suo's picture

iMechanica has just upgraded to Drupal 5. Any issues?

After testing for some time, Lesley Lam has just upgraded iMechanica to Drupal 5.  She has tried to make every function exactly the same as before, so that users should not see any abrupt changes.  If you do find any unfamiliar behavior of the new version, please leave a comment below.


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