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Quantum Stability of Metallic Thin Films and Nanostructures

Submitted by Zhenyu Zhang on
research
Mechanics in the quantum regime

When a metal system shrinks its dimension(s), the conduction electrons inside the metal feel the squeezing, and are forced into (discrete) quantum states. Such confined motion of the conduction electrons may influence the global or local stability of the low dimensional systems, and in the case of a thin film on a foreign substrate this "quantum energy" of electronic origin can easily overwhelm the strain effects in definging the film stability, thereby severely influencing the preferred growth mode (see, e.g., Suo and Zhang, Phys. Rev. B 58, 5116 (1998)).

Spacing effect on dislocation injection from sharp features in strained silicon structures

Submitted by Juil Yoon on
strained silicon
dislocation nucleation
stress intensity factor

In practice, the SiN stripes or pads are periodically patterned on silicon, so the spacing effect on dislocation injection from sharp features deserves attention. As in Figure 1, the SiN stripes with residue stress, of width L and thickness h, are periodically patterned with spacing S. In the numerical calculation, we take shear modulus and Poisson’s ratio of Si3N4 to be 54.3 GPa and 0.27, and those of silicon 68.1GPa and 0.22, the same as in Ref.[1].

Symposium on Characterization and Modeling of Time-Dependent Materials and Processes at the 2007 ASME M&M Conference

Submitted by H Jerry Qi on
conference
McMat 2007

The Symposium on Characterization and Modeling of Time-Dependent Materials and Processes at the 2007 ASME Mechanics and Materials conference will be held June 3-7, 2007, at the University of Texas at Austin. Additional information about the conference can be found at the conference website.

Papers dealing with modeling and experimental aspects of the subject area, involving all materials, are sought. The mechanical response should be non-negligable in cases involving non-mechanical fields. Possible topics include, but are not limited to: characterization and modeling of behavior at multiple scales; viscoelasticity, viscoplasticity; transport, chemically and electronically active processes; multiphase and biomaterial systems; thermodynamics; shape memory; mechanics of testing; micro/nanoindentation on time-dependent materials; dynamic behavior of polymers and composites; large deformations; residual stresses; time-dependent damage and failure; polycrystalline and single crystal behaviors; multifunctional materials; mechanics of processing.

Postdoctoral Position in Micromechanics and Fatigue of Natural Composites, at Risø National Laboratory, Denmark

Submitted by Leon Mishnaevsky on
job


Applications are invited from suitably qualified candidates for a Postdoc/Research Scientist position in the framework of a Danish/Nepalese collaborative research project, in the Materials Research Department of Risø National Laboratory, Denmark 

Job description: As a postdoc/scientist, you will carry out numerical micromechanical modelling of fatigue processes in wood. The theme of the project is the computational analysis of the effect of microstructures of natural materials (wood), coatings and other microscale parameters on their fatigue resistance and lifetime under cyclic loading. The experiments and verification of results will be carried out in collaboration with project partners in Kathmandu, Nepal. The deliverables of the project should include the development of recommendations for the improvement of the reliability of wind turbine blades, produced from coated wood in Nepal, as well as extracting “lessons from nature” to be used in the improvement of polymer matrix fiber reinforced composites for wind energy applications.  

Mechanics and deformation of the nucleus in micropipette aspiration experiment

Submitted by Ashkan Vaziri on
research
biomechanics
computational mechanics
cell biomechanics

Robust biomechanical models are essential for studying the nuclear mechanics and can help shed light on the underlying mechanisms of stress transition in nuclear elements. Here, we develop a computational model for an isolated nucleus undergoing micropipette aspiration. Our model includes distinct components representing the nucleoplasm and the nuclear envelope. The nuclear envelope itself comprises three layers: inner and outer nuclear membranes and one thicker layer representing the nuclear lamina.

Atomistic simulations for the evolution of a U-shaped dislocation in fcc Al

Submitted by Xiaoyan Li on
research
molecular dynamics
dislocation multiplication
Frank-Read source

We show, through MD simulations, a new evolution pattern of the U-shaped dislocation in fcc Al that would enrich the FR mechanism. Direct atomistic investigation indicates that a U-shaped dislocation may behave in different manners when it emits the first dislocation loop by bowing out of an extended dislocation. One manner is that the glissile dislocation segment always bows in the original glide plane, as the conventional FR mechanism. Another is that non-coplanar composite dislocations appear owing to conservative motion of polar dislocation segments, and then bow out along each slip plane, creating a closed helical loop. The motion of these segments involves a cross-slip mechanism by which a dislocation with screw component moves from one slip plane into another. Ultimately, such non-coplanar evolution results in the formation of a FR source.

NEW ERASMUS MUNDUS MASTER COURSE IN COMPUTATIONAL MECHANICS

Submitted by Nicolas MOES on
education
master

I am writing to you to bring to your attention a new Master Course on Computational Mechanics, which has been awarded the Erasmus Mundus label.

It is an international Master course given jointly in English by the Universidad Politécnica de Cataluña (Barcelona), University of Wales Swansea), Ecole Centrale Nantes and Universität Stuttgart with the collaboration of CIMNE International Centre for Numerical Methods in Engineering, Barcelona). The Erasmus Mundus program:

Prototype for a journal in iMechanica

Submitted by Eloy Villanueva on

Hi fellow mechanicians,

Professor Suo and I have devised a model for creating a journal on iMechanica. It is a simple model which doesn’t require installing any additional modules or features.

We simply let a user be a journal manager, and he selects excellent blog entries as articles to be published in the next issue of the journal. He will then create a blog entry listing the titles of the articles with their respective authors and make each title a link to the original post. This way another user only needs to click on the title of an article to see the full entry.

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