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Axial-Strain-Induced Torsion in Single-Walled Carbon Nanotubes

Submitted by Haiyi Liang on
Forums
Materials Forum
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carbon nanotubes

Using classical molecular dynamics and empirical potentials, we show that the axial deformation of single-walled carbon nanotubes is coupled to their torsion. The axial-strain-induced torsion is limited to chiral nanotubes—graphite sheets rolled around an axis that breaks its symmetry. Small strain behavior is consistent with chirality and curvature-induced elastic anisotropy (CCIEA)—carbon nanotube rotation is equal and opposite in tension and compression, and decreases with curvature and chirality. The largestrain compressive response is remarkably different.

New Book "Tissue Mechanics"

Submitted by MichelleLOyen on
education
textbook
biomechanics
book

A new book, "Tissue Mechanics" by SC Cowin and SB Doty is of potential interest to those from a classical mechanics background considering work in biomechanics. Downloadable versions of the first two chapters are available at the book's website along with a full table of contents and other supplemental information.

DEPARTMENT CHAIR: San Diego State University, Department of Mechanical Engineering

Submitted by Eugene A. Olevsky on
job

The Department of Mechanical Engineering invites applications and nominations for the position of Department Chairperson to begin in Fall 2007.

Applicants must hold an earned PhD in Mechanical Engineering or closely related discipline. A record of leadership showing interpersonal skills and organizational ability, strong research background and funding records with recognized professional accomplishments in mechanical engineering, demonstrated ability to interact with industry, and a commitment to excellence in teaching at both undergraduate and graduate levels are required. Mechanical Engineering is one of four departments in the College of Engineering at San Diego State University with an EAC, ABET-accredited B.S. degree program in Mechanical Engineering, as well as M.S. and Ph.D. programs involving students in leading edge research.

Heritage for Experimental Mechanicians

Submitted by Kyung-Suk Kim on

On July 16, 1976, when I was writing my very first paper in U.S. with my lab senior Dr. Prashant Kumar and thesis advisor Professor Rodney J. Clifton to the Journal of Applied Physics, Professor Clifton put a copy of an article on my desk while I was away. The article was "Advice to Young Physicists" by Walther Bothe. It was translated from German to English in Physics Today, September, 1958. I do not know whether this advice still holds for the whole; however, I believe that most of the advice is still valuable for anyone, in particular, an experimentalist, who undertakes a piece of scientific work. Therefore, I would like to share his advice with the society of iMechanica by recollecting it here. - K.-S. Kim

Non linear cell mechanics

Submitted by Daniel Isabey on
research

Ex-vivo measure of stress-strain relationships in populations of living adherent cells by means of ligand-coated ferromagnetic microbeads (mean diameter: 4.5 µm) attached to the transmembrane mechanoreceptors which are linked to the cytoskeleton (CSK), reveal non linear cell mechanical behavior. However, this non linear cell mechanical behaviour is subjected to controversy for various reasons. First, it has not been systematically found. Results seem to depend on the micromanipulation method used and/or the cell type.

What is Grid Computing? How can it be important to mechanicians? When?

Submitted by Zhigang Suo on
Forums
Technology Corner
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computational mechanics
Grid Computing

At the suggestion of Joy Sircar, the Chief Technology Officer at the School of Engineering and Applied Sciences, of Harvard University, iMechanica has just added a forum called Technology Corner. As Joy has framed it, this new forum intends to host conversations on software and hardware technologies that might be relevant to mechanicians.

Here is a question I have. Lately I've heard the phrase Grid Computing a number of times. It is about networking lots of computers and other electronic devices, and supply users with computing power like supplying electricity. That is, computing power will become a utility. One might even hope software will also become utilities. Some people say that Grid Computing will happen in just a few years, or may be already here. Here is a collection of essays in Nature on 2020 Future of Computing.

Effect of surface energy on the yield strength of nanoporous materials

Submitted by Weixu Zhang on
research
Plasticity
surface energy
yield strength

This is a very rough manuscript but including the original material we used. Any criticism or suggestion is welcome. The only aim of this letter is to reflect the multi-effect of surface energy on material or structure in nanosize scale. Here we report the effect of surface energy on the yield strength of nanoporous materials. The conventional micromechanics method is extended to consider the surface effect and expression of effective yield surface of nanoporous materials in complex stress state is derived.

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