I am at Boston for MRS 2006 Fall meeting this week, where I met a real "spiderman" at the poster session tonight. I'd like to share with you the following videos which were posted at YouTube by the "spiderman" himself, Mr. Jose Berengueres at Tokyo Instititute of Technology.
Mr. "Spiderman" also has posted a video on fasting climbing robot.
A variable core model of a moving crystal dislocation is proposed and used to derive an expression for the Peierls stress. The dislocation width varies periodically as a dislocation moves through the lattice, which leads to an expression for the Peierls stress in terms of the difference of the total energies in the crystal corresponding to stable and unstable equilibrium configurations of the dislocation, rather than the difference in the misfit energies alone. Results for both edge and mixed dislocations are given and proposed to be used in conjunction with ab initio calculations.
Mechanics of Solids and Materials intends to provide a modern and integrated treatment of the foundations of solid mechanics as applied to the mathematical description of material behavior. The book blends both innovative (e.g., large strain, strain rate, temperature, time-dependent deformation and localized plastic deformation in crystalline solids, and deformation of biological networks) and traditional topics (e.g., elastic theory of torsion, elastic beam and plate theories, and contact mechanics) in a coherent theoretical framework. This, and the extensive use of transform methods to generate solutions, makes the book of interest to structural, mechanical, and aerospace engineers.
The German Academic Exchange Service (DAAD) - in cooperation with science organizations in North America and Germany— is to invite undergraduate students from the US and Canada in the fields of biology, chemistry, physics, earth Sciences and engineering to apply for a summer research internship in Germany. RISE summer placements take place with research groups at universities and top research institutions across Germany. The RISE interns are matched with a doctoral student whom they assist and who will also serve as their mentor. This program is funded by the Federal Ministry of Economics and Technology as part of the European Recovery Program (ERP).
More details at http://www.daad.de/rise/en/1.html.
Nature 439, 281 (2006)
The theoretical maximum tensile strain — that is, elongation — of a single-walled carbon nanotube is almost 20%, but in practice only 6% is achieved. Here we show that, at high temperatures, individual single-walled carbon nanotubes can undergo superplastic deformation, becoming nearly 280% longer and 15 times narrower before breaking. This superplastic deformation is the result of the nucleation and motion of kinks in the structure, and could prove useful in helping to strengthen and toughen ceramics and other nanocomposites at high temperatures.
The time-dependent plastic deformation (creep) behaviors of both the as-deposited and annealed plasma-enhanced chemical vapor deposited (PECVD) silicon oxide (SiOx) films were probed by nanoindentation load relaxation tests at room temperature. Our experiments found a strong size effect in the creep responses of the as-deposited PECVD SiOx thin films, which was much reduced after rapid thermal annealing (RTA). Based on the experimental results, the deformation mechanism is depicted by the "shear transformation zone" (STZ) based amorphous plasticity theories. The physical origin of the STZ is elucidated and linked with the shear banding dynamics. It is postulated that the high strain gradient at shallow indentation depths may be responsible for the reduction in the stress exponent n=∂log(strain rate)/∂log(stress), characteristic of a more homogenous flow behavior.
Gold films on an elastomeric substrate can be stretched and relaxed reversibly by tens of percents. The films initially form in two different structures, one continuous and the other containing tri-branched microcracks. We have identified the mechanism of elastic stretchability in the films with microcracks. The metal, which is much stiffer than the elastomer, forms a percolating network.
In early days of Applied Mechanics News, I encountered a practical problem. How do we call ourselves? I began with a phrase "people in the international community of applied mechanics". The phrase is inclusive and descriptive, but is too long, too timid and too clumsy. It is like calling entropy "the logarithm of the number of quantum states". I have also heard the phrase "mechanics people", which I don't like either. It sounds too folksy, like calling a gynecologist a women's doctor.
More than fifty years ago, people realized that we can use fusion for energy, but the problem remains where and how to keep a plasma of 100 million degrees centigrade.
For TOKAMAK, one of the approaches to use the fusion power, now comes the news: "On 21 November, Ministers from the seven ITER Parties came together to sign the agreement to establish the international Organization that will implement ITER."
