iMechanica

Variational theory of elasticity is surveyed in the context of mathematical logic in the present paper titled "Variational Theory: Variable-independence and Consistency" . The problem of variable-independence of variational principles raised by Professor Chien Wei-zang is discussed.

 Hi Everybody, Im new to iMechanica. I must admit If I knew of it earlier it could have changed so many things in my life :). Im really glad to be here now. For a start I would like to ask if anyone has any links /sources to this book. I simply cant find it. Ive checked Amazon etc etc. Please help me find this book

"HELICOPTERS: CALCULATION AND DESIGN. VIBRATIONS AND DYNAMIC STABILITY "(Mil, M. L. ; Nekrasov, A. V. ; Braveman, A. S. ; Grodko, L. N. ; Leikand, M.) 1968.

Rgds.

Dominic.

A new AP article appeared today on  free access to college's educational materials, particularly spot-lighting the MIT Open Course Ware initiative.   Also discussed are available educational materials through iTunes and Youtube.   iMechanica has also got a growing repository of course notes on mechanics topics. 

Can we map the eastic modulus of a and c domians? Can we mechanically switch the domains and let them function as nanoactuators and sensors?

Hello! 

As a student who has spent a lot of time studying cohesive zone models in fracture mechanics, I have several questions that have bothered me over the past year or so, and I have not been able to find suitable answers to them. I am limiting myself here to questions related to the traction-separation law, which invariably forms the basis of CZM as it is implemented today. I am raising these questions in the hope that I can receive some response here, even if it means my question is invalid (as I suspect a few may be).  So here is my list:

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Fascinating paper. Congrats to Wei, Xuanhe, and Zhigang. Nice to see a simple and an elegant model together with an intuitively appealing physical interpretation of the bifurcation phenomenon in gels. It woud be interesting to see the time evolution of the drying process and the orientation (theta) of the nano wires.  

A polymer network can imbibe water from environment and swell to an equilibrium state. If the equilibrium is reached when the network is subject to external mechanical constraint, the deformation of the network is typically anisotropic, and the concentration of water inhomogeneous.  Such an equilibrium state in a network constrained by a hard core is modeled here with a nonlinear differential equation.  The presence of the hard core markedly reduces the concentration of water near the interface and causes high stresses.

Hydrogels have enormous potential for making adaptive structures in response to diverse stimuli.  In a structure demonstrated recently, for example, nanoscale rods of silicon were embedded vertically in a swollen hydrogel, and the rods tilted by a large angle in response to a drying environment (Sidorenko, et al., Science 315, 487, 2007).  Here we describe a model to show that this behavior corresponds to a bifurcation at a critical humidity, analogous to a phase transition of the second kind.

At 71, Physics Professor Is a Web Star

Most frequently e-mailed by NYTimes.com readers in the past 30 days, the above article features MIT physics professor, Walter H. G. Lewin, on how his free physics lecture videos online have won him devotees all over the world.

EPFL continues to strengthen its School of Architecture, Civil and Environmental Engineering (ENAC). We are recruiting an assistant professor (tenure track) in structural engineering. In special cases, a senior faculty appointment could be considered. We are seeking exceptional candidates with a strong interest in teaching and an outstanding record of scientific accomplishments.

I had promised to talk about subversion in my post on digitizing and editing figures but never quite got around to it. A recent spate of requests about downloading Uintah reminded me of my promise. So here's the story.

Dear Colleagues:

We invite you to submit an abstract in our mini-symposium titled

Length Scale Effects in Dynamic Failure of Materials

at

8th. World Congress on Computational Mechanics (WCCM8)

5th. European Congress on Computational Methods in Applied Sciences and Engineering (ECCOMAS 2008)

June 30 - July 4, 2008

Lido Island, Venice, Italy

A new type of elasticity of random (multifractal) structures is suggested. A closed system of constitutive equations is obtained on the basis of two proposed phenomenological laws of reversible deformations of multifractal structures. The results may be used for predictions of the mechanical behavior of materials with multifractal microstructure, as well as for the estimation of the metric, information, and correlation dimensions using experimental data on the elastic behavior of materials with random microstructure.

Professor Y. C. Fung, Professor Emeritus of Bioengineering at UC San Diego's Jacobs School of Engineering, is the recipient of the Fritz J. and Dolores H. Russ Prize of 2007.

The Russ Prize is presented biannually to an outstanding candidate in the field of bioengineering who has made significant contributions to improving the human condition through research, development, teaching, or management. The recipient receives a $500,000 cash award and an engraved gold medallion.

Hi every oneI am doing my master in civil engineering at U.K.M. University in Malaysia. I want to learn 1 FEM software. But I don’t no which of them is better for me ,ansys or abaqus?. My thesis is about concrete filled tubular.

I must model concrete and steel, and I think I face contact problem to define connection between concrete and steel.

I will be very pleased if someone helps me.

The physics associated with self-affine crack formation and propagation is discussed. Some novel concepts are suggested for the mechanics of self-affine cracks. These concepts are employed to model the crack face morphology and, in turn, to solve various problems with self-affine cracks. It is shown that linear elastic fracture mechanics (LEFM) is a special case of self-affine crack mechanics and should be used only in length scales larger than the self-alfine correlation length. The theoretical results are confirmed by available experimental data.

We found that randomly folded thin sheets exhibit unconventional scale invariance, which we termed as an intrinsically anomalous self-similarity, because the self-similarity of the folded configurations and of the set of folded sheets are characterized by different fractal dimensions. Besides, we found that self-avoidance does not affect the scaling properties of folded patterns, because the self-intersections of sheets with finite bending rigidity are restricted by the finite size of crumpling creases, rather than by the condition of self-avoidance.

This paper presents a geometric discretization of elasticity when
the ambient space is Euclidean. This theory is built on ideas from
algebraic topology, exterior calculus and the recent developments
of discrete exterior calculus. We first review some geometric
ideas in continuum mechanics and show how constitutive equations
of linearized elasticity, similar to those of electromagnetism,
can be written in terms of a material Hodge star operator. In the
discrete theory presented in this paper, instead of referring to