Internal lattice relaxation of single-layer graphene under in-plane deformation
This paper has been published in Journal of the Mechanics and Physics of Solids 56 (2008), pp. 1609-1623 (doi:10.1016/j.jmps.2007.07.013).
Abstract
BIOMECHANICAL STUDY OF GOLF BALL IMPACT ON CHILD’S HEAD USING THE FINITE ELEMENT METHOD
Head traumatic injury due to the impact of a flying golf ball is one of the severest injuries sustained on a golf course. This paper presents numerical simulation results based on the finite element (FE) method to investigate head injuries in children due to impacts by flying golf balls.
Some weekend reading
Terence Tao (one of the Fields Medal winners this year) has started blogging. He has a detailed discussion on the Navier-Stokes equations here. It's long but definitely worth reading - particularly because of the wide range of ideas that he talks about.
J-club Editor: Election versus Appointment?
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As many of you know, last year we had a lively debate prior to the launch of the j-club regarding the rules and regulations governing the functioning of the j-club. This continued in a more low-key fashion this year. One of the more important topics under discussion has been the selection of the future editors (which is to be done each year). I, and perhaps a few other people, had reasoned that the editor should be elected by popular vote. It was proposed that candidates will either self-nominate themselves or be nominated by other mechanicians.
The Leonhard Euler Tercentenary
Just a reminder that this Sunday, April 15 will be exactly 300 years since Leonhard Euler was born.
I am sure many mechanicians will toast this weekend on this extraordinnary anniversary to the person who laid down much of the foundations in mathematics and mechanics.
Some of the related links on the web are:
Symposium on Microelectromechanical Systems: Materials and Devices, MRS Fall 2007
From the Call for Papers:
Microelectromechanical Systems (MEMS) represent the integration of miniaturized mechanical, chemical, fluidic, and optical devices with microelectronics. MEMS have a broad range of applications in optical- and radio-frequency communications, physical/chemical/biosensing, display technology, drug delivery, and the manipulation and isolation of cells.
Fundamentals of Nanoindentation and Nanotribology IV at MRS Fall 2007
First announcement and call for papers.
The symposium "Fundamentals of Nanoindentation and Nanotribology" will run for the fourth time at the Fall, 2007, Materials Research Society Meeting, Boston, MA, USA.
On the uniqueness of measuring elastoplasticproperties from indentation
Indentation is widely used to measure material mechanical properties such as hardness, elastic modulus, and fracture toughness (for brittle materials). Can one use indentation to extract material elastoplastic properties directly from the measured force-displacement curves? Or simply, is it possible to obtain material stress-strain curves from the corresponding indentation load-displacement curves? In an upcoming paper in JMPS titled "On the uniqueness of measuring elastoplastic properties from indentation: The indistinguishable mystical materials," Xi Chen and colleagues at Columbia University and National Defense Academy, Japan show the existence of "mystical materials", which have distinct elastoplastic properties yet they yield almost identical indentation behaviors, even when the indenter angle is varied in a large range. These mystical materials are, therefore, indistinguishable by many existing indentation analyses unless extreme (and often impractical) indenter angles are used. The authors have established explicit procedures of deriving these mystical materials. In many cases, for a given indenter angle range, a material would have infinite numbers of mystical siblings, and the existence maps of the mystical materials are also obtained. Furthermore, they propose two alternative techniques to effectively distinguish these mystical materials. The study in this paper addresses the important question of the uniqueness of indentation test, as well as providing useful guidelines to properly use the indentation technique to measure material elastoplastic properties.