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MichelleLOyen's picture

We must not forget to teach the fundamentals

An interesting blog discussion on the disappearance of fundamentals from teaching in Universities was brought to my attention.  It serves as an interesting reminder that we who are educators in the University system must be ever vigilent in planning mechanics curricula and changes to curriculum.  Should we be offering courses in the area of this month's jClub, "Nanomechanics"?  Should we drop classical courses that have stopped being interesting to the majority of students (and thus attract low numbers)?  Should we educate students explicitly in biomechanics without providing them a classical mechanics background?  These are the questions we are likely to face in the next few years as change continues to sweep across the university system, especialy in the US but elsewhere as well.  I believe that we as a community have a responsibility here to ensure that the high standards of the discipline are maintained through teaching of fundamentals and the passing along of these values to future generations!

Zhigang Suo's picture

Problem for registration has been fixed

On Wednesday morning, I received an email from Anastassia Paskaleva. She was unable to create an account on iMechanica, because CAPTCHA kept telling her that she typed the letters wrong. Lesley Lam, iMechanicia user number 1, has just fixed the problem. Now new users can register once more. We apologize for the inconvenience that this problem might have caused you, and thank Anastassia for letting us know the problem.

Chwee Teck Lim's picture

GEM4 Summer School on Cell & Molecular Mechanics in Biomedicine 2007 - NUS, Singapore

 GEM4 Summer School 2007 on Cell & Molecular Mechanics in Biomedicine (with a focus on Cancer)

25 June to 6 July 2007

http://groups.google.com/group/F-E-A

Invitation to join the Finite Element Analysis Google Group.

Many information about finite element analyses is added by users.

Mogadalai Gururajan's picture

On the need for popular science articles by mechanicians

Recently, the Royal Society Science book prize shortlist was announced; though the shortlisted books cover psychology, evolution, biodiversity, medicine and neurobiology, none in the area of materials or mechanics made it to the list. Or, pick any Best American Science writing volume--there are hardly any articles about materials or mechanics that make it to these anthologies.

Zhigang Suo's picture

Instabilities

  • Free energy and generalized coordinate. Equilibrium and stability
  • Control parameter
  • Configurational transitions of two types
  • Critical point of configurational transition of the second type. Bifurcation analysis
  • Behavior near a critical point. Post-bifurcation analysis
  • Load-displacement relation near a critical point
  • Koiter's theory of imperfection sensitivity
  • A family of systems of many degrees of freedom
  • Mode of bifurcation
  • Vibration in the neighborhood of an equilibrium configuration

The 2007 Melosh Medalists

The 19th Annual Melosh Competition for the Best Student Paper in Finite Element Analysis was held last Friday, April 27, at ETH Zurich. Two medalists were selected this year from the six finalists. The 2007 Melosh Medalists are Vikram Gavini, from Caltech, and Michael Hain, from Leibniz University, Hannover.

Zhigang Suo's picture

David Turnbull died on 28 April 2007

David Turnbull died peacefully at home last Saturday, April 28th, at age 92.

He was for many years Gordon McKay Professor of Applied Physics at Harvard University. His seminal work included theoretical and experimental studies of nucleation of crystals, the glass transition and the amorphous state, crystal growth, and atomic diffusion.

Xiaodong Li's picture

Journal Club Theme of May 2007: Experimental Mechanics of Nanobuilding Blocks

Welcome to the May 2007 issue. This issue focuses on experimental nanomechanics of nanobuilding blocks. The extremely small dimensions of nanobuilding blocks (for instance, nanoparticles, nanotubes, and nanowires) have imposed great challenges to many existing instruments, methodologies, and even theories.  In this issue, we will discuss – (1) experimental techniques and (2) size-effects. 

Super stretchy carbon nanotubes

Huang et al., PRL 98, 185501 (2007)

Watch movies at: http://netserver.aip.org/cgi-bin/epaps?ID=E-PRLTAO-98-002719

We report exceptional ductile behavior in individual double-walled and triple-walled carbon nanotubes at temperatures above 2000 C, with tensile elongation of 190% and diameter reduction of 90%, during in situ tensile-loading experiments conducted inside a high-resolution transmission electron microscope. Concurrent atomic-scale microstructure observations reveal that the superelongation is attributed to a high temperature creep deformation mechanism mediated by atom or vacancy diffusion, dislocation climb, and kink motion at high temperatures. The superelongation in double-walled and triple-walled carbon nanotubes, the creep deformation mechanism, and dislocation climb in carbon nanotubes are reported here for the first time.

Henry Tan's picture

Surface roughness evolution

With a shallow chemical etching the roughness with spatial frequency below a critical value grows while the roughness of higher frequency decays.

node/1312

Ken P. Chong's picture

NSF Proposal Writing Workshop

Subject: NSF Proposal Writing Workshop ( August 22-23, 2007 - Alaska)

Sponsored by NSF, a Proposal Writing Workshop will be held on August 22-23, 2007, at University of Alaska-Fairbanks. The workshop mainly aims to provide future proposal submitters (in all disciplines funded by NSF) with knowledge and tools to write good proposals, proposal review experience, and it will enable interactions with NSF program directors and recent NSF awardees. The event is targeted at an EPSCoR state, Alaska. However, the workshop is open to participants from other states as space permits.

MichelleLOyen's picture

Adhesion in viscoelastic contacts

Yesterday I had the distinct pleasure of seeing a mechanics seminar delivered "tag-team" by Ken Johnson and Jim Greenwood. (I know several people have thought I was a bit mad for jumping "across the pond" but there are really some amazing benefits of being part of the Cambridge Engineering faculty!)

Mogadalai Gururajan's picture

Going beyond 2D Neumann-Mullins (or, what is popularly known as, solving the beer froth structure)

Introduction

The blogosphere is abuzz with the latest report of the generalisation of the von Neumann-Mullins grain growth relation to 3 (and N) dimensions by MacPherson and Srolovitz (As an interesting aside, almost all the reports say mathematical structure of beer foam structure resolved, or words to that effect --hence, I also decided to join the bandwagon on that one). I heard Prof. Srolovitz describe the work in a seminar nearly six months ago. Based on my notes of the talk, I would like the explain their work in this post. Curvature in the following refers to mean curvature (and not Gaussian).

Microcantilever operated in liquid environment for in-vitro biomolecular detection

We have recently reported the piezoelectric thick film microcantilever, which enables the in-situ real-time detection of the protein related to disease (e.g. C reactive protein) in liquid environment. This work was published at APL (click here).

"In-situ real-time monitoring of biomolecular interactions based on resonating microcantilevers immersed in a viscous fluid"

Mogadalai Gururajan's picture

Sample issue of Journal of Materials, a TMS publication

JOM is a monthly publication of TMS--The minerals, metals, and materials society. It covers a wide range of materials topics. I expecially like the overview articles, which, in four or five pages pack lots of information. Further, the historical articles about metallurgy and materials in ancient civilizations will interest those of you who like to read about history in general, and science history, in particular.

Chip-package interaction and interfacial delamination

In flip-chip package, the mismatch of thermal expansion coefficients between the silicon die and packaging substrate induces concentrated stress field around the edges and corners of silicon die during assembly, testing and services. The concentrated stresses result in delamination on many interfaces on several levels of structures, in various length scales from tens of nanometers to hundreds of micrometers. A major challenge to model flip-chip packages is the huge variation of length scales, the complexity of microstructures, and diverse materials properties. In this paper, we simplify the structure to be silicon/substrate with wedge configuration, and neglect the small local features of integrated circuits. This macroscopic analysis on package level is generic with whatever small local features, as long as the physical processes of interest occur in the region where the concentrated stress field due to chip-packaging interaction dominates. Because it is the same driving force that motivates all of the flaws. Therefore, the different interface cracks with same size and same orientation but on different interfaces should have similar energy release rates provided that the cracks are much smaller than the macroscopic length. We calculate the energy release rate and the mode angle of crack on the chip-package interface based on the asymptotic linear elastic stress field. In a large range of crack length, the asymptotic solution agrees with finite element calculation very well. We discuss the simplified model and results in context of real applications. In addition, we find that the relation of energy release rate G and crack length a is not power-law since local mode mixity is dependent of crack length a. Therefore, the curve of G~a can be wavy and hardly goes to zero even if crack length a goes to atomically small. The local mode mixity plays an important role in crack behavior.

Robert Paynter's picture

iMechanica needs a logo

I agree with Michelle, we need to get beyond the default Drupal water drop.

How about my little offering, that came to mind:

 

It's overall shape approximates that of the letter i

At a glance it can look like a Mass on a Spring - major components of mechanics.

It has a globe because this is international

and it says iMechanica at the bottom.

Sure, it need some polishing, but perhaps offers a start.

Robert

Oxford, UK

Taxonomy upgrade extras: 
zhan-sheng guo's picture

ICNM 2007

The International Conferences on Nonlinear Mechanics (ICNM-x) have been regarded as important series conferences in mechanics circles. The previous four meetings in the series were successfully held in Shanghai and Beijing in 1985, 1993, 1998 and 2002, respectively. In recent years, new achievements in this field have been made. Therefore, it is appropriate to organize a new conference on this vitally important area of applied mathematics and mechanics. The Fifth International Conference on Nonlinear Mechanics (ICNM-V) will be held in Shanghai. The Conference aims to provide an international forum for presenting the latest results and stimulating wider academic exchange for experts in the related fields all over the world.

Marek-Jerzy Pindera's picture

In Memory of Professor Liviu Librescu

I had known Liviu since his early days in the Engineering Science and Mechanics Department at Virginia Tech when I was just beginning my own academic career. I had received my PhD from this department in 1981 in an area (composite materials) that at the time was at the cutting edge of high technology. In 1985 I had come back to VA Tech from the industry to continue working in this exciting area in which the ESM Department excelled world-wide. Liviu had arrived shortly thereafter with an already established reputation as a top-notch scientist.

Xuanhe Zhao's picture

Electromechanical hysteresis and coexistent states in dielectric elastomers

Active polymers are being developed to mimic a salient feature of life: movement in response to stimuli. Large deformation can lead to intriguing phenomena; for example, recent experiments have shown that a voltage can deform a layer of a dielectric elastomer into two coexistent states, one being flat and the other wrinkled. This observation, as well as the needs to analyze large deformation under diverse stimuli, has led us to reexamine the theory of electromechanics.

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