Strength of graphenes containing randomly dispersed vacancies

Once in a while I have to find the stiffness of a spring that I get from the local hardware shop.  I usually use a formula that can be found in some books on mechanics of materials.

But the assumptions bother me a bit because the springs that I used usually underwent large deformations and I wasn't sure whether the numbers I was using were correct or not.  

To check the formula I compared its predicted k to numbers from Abaqus simulations and found reasonably good results for many situations - but not for soft springs.

Attached is an intriguing commentary on the scientific method through an example, written by my good friend, Luc Tartar. The specific example is that of trying to understand what 'light' might be, especially from a mathematician's point of view. The mathematician in this case is an extremely talented one, who also happens to actually understand a whole lot of physics and mechanics.

For an interesting news article about the mechanics behind Lego Man's balloon voyage to space, read the Toronto Star article by Mary Ormsby. She writes, "A 1,200-gram weather balloon, the crucial role of gravity, quiver-reducing ropes, Styrofoam’s versatility, burst altitude, a University of Wyoming website and a free software program for shutterbugs were part of the formula Mathew Ho and Asad Muhammad, both 17, used to launch, film and land the patriotic, flag-bearing Lego Man..."

A Special Issue of Engineering Fracture Mechanics

on

"Fracture and contact mechanics for interface problems", edited by Marco Paggi, Alberto Carpinteri and Peter Wriggers has just been published:

http://www.sciencedirect.com/science/journal/00137944/80

The selected articles were presented in a Minisymposium of the IV European Conference on Computational Mechanics, Paris, France, 2010.

Far greater voltage-actuated deformation is achievable for a dielectric elastomer under equal-biaxial dead load than under rigid constraint usually employed. Areal strains of 488% are demonstrated. The dead load suppresses electric breakdown, enabling the elastomer to survive the snap-through electromechanical instability. The breakdown voltage is found to increase with the voltage ramp rate. A nonlinear model for viscoelastic dielectric elastomers is developed and shown to be consistent with the experimental observations. 

Published Online:

We seek for highly motivated
Ph.D. candidates in the field of 1) Acoustic metamaterials (e.g., phononic

Dear all,

Herewith I want to announce the release of the frictional rolling contact model CONTACT version 12.1.

The main changes with respect to earlier versions of the program are as follows:

A postdoctoral position with
primary focus on finite element simulations of active biopolymer
networks is available immediately at Shenoy Research Group @ Brown University . We are looking for a strongly
motivated candidate to work on the mechanics of active cytoskeletal
networks. The ideal candidate will have a background in solid
mechanics/computational physics with expertise in finite element simulations. Experience with Monte Carlo methods and stochastic simulations is desired but not essential.  This
individual will have the opportunity to be directly involved in