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Mogadalai Gururajan's blog

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Growth kinetics of precipitates: misfitting and non-misfitting

Quantitative studies on diffusional growth of an isolated
precipitate in a supersaturated matrix date back to the classic work of
C Zener (1949) and F C Frank
(1950); while Zener-Frank (ZF) theory is for precipitates that are
non-misfitting, misfitting precipitates have been studied by Laraia,
Johnson and Voorhees (1988) (hereafter, LJV). Both ZF and LJV are sharp
interface models (and are mostly analytical); further, the assumptions
made in these theories make it difficult to verify their results by

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An e-book on engineering fracture mechanics

Here is an e-book on Engineering Fracture Mechanics ; you can also download a demo version, the preface, and other related stuff from the page. The idea of the book (as described in the page) sounds interesting:

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New category for open source codes

Update: An Open Source Review page has been created. Please feel free to leave links, codes and comments on the page. 

Dear Mechanicians,

I have seen that there is lot of code sharing among the mechanicians at iMechanica; a search for the word "code" for example produces nearly fifty entries, of which, I believe, at least half of the posts are pointers to codes and their sharing.

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On the need for popular science articles by mechanicians

Recently, the Royal Society Science book prize shortlist was announced; though the shortlisted books cover psychology, evolution, biodiversity, medicine and neurobiology, none in the area of materials or mechanics made it to the list. Or, pick any Best American Science writing volume--there are hardly any articles about materials or mechanics that make it to these anthologies.

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Going beyond 2D Neumann-Mullins (or, what is popularly known as, solving the beer froth structure)

Introduction

The blogosphere is abuzz with the latest report of the generalisation of the von Neumann-Mullins grain growth relation to 3 (and N) dimensions by MacPherson and Srolovitz (As an interesting aside, almost all the reports say mathematical structure of beer foam structure resolved, or words to that effect --hence, I also decided to join the bandwagon on that one). I heard Prof. Srolovitz describe the work in a seminar nearly six months ago. Based on my notes of the talk, I would like the explain their work in this post. Curvature in the following refers to mean curvature (and not Gaussian).

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Sample issue of Journal of Materials, a TMS publication

JOM is a monthly publication of TMS--The minerals, metals, and materials society. It covers a wide range of materials topics. I expecially like the overview articles, which, in four or five pages pack lots of information. Further, the historical articles about metallurgy and materials in ancient civilizations will interest those of you who like to read about history in general, and science history, in particular.

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Modelling nanoscale properties

In an inaugural article in the latest issue of PNAS, George C Schatz writes on Using theory and computation to model nanoscale properties. Here is the abstract of the article:

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Open source codes for microstructural evolution

Modelling and simulation is sometimes said to be the third way of doing science, the first two being theory and experiment; see this essay in Science for example:

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Harder than diamond: Rhenium diboride

In the recent issue of Science, researchers from UCLA (Chung et al) report on an ambient pressure synthesis (using arc melting) of a compound, namely, rhenium diboride, which is superhard. Apparently, the material leaves scratch marks on the surface of diamond. Here is the abstract of the paper:

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Computer simulations and visualization: Seed video

Here is a video from the Seed magazine called Science in Silico. The video shows results from large scale simulations (and visualization) of fractals, microscopic dynamic processes in ribosomes, structure of viruses, bacterial flagellum, turbulence, explosions, and the modelling of cosmological events.

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Elastic stress driven phase inversion

A typical two phase microstructure consists of a topologically continuous `matrix' phase in which islands of `precipitate' phase are embedded. Usually, the matrix phase is also the majority phase in terms of volume fraction. However, sometimes this relationship between the volume fraction and topology is reversed, and this reversal is known as phase inversion. Such a phase inversion can be driven by an elastic moduli mismatch in two-phase solid systems. In this paper (submitted to Philosophical magazine), we show phase inversion, and the effect of the elastic moduli mismatch and elastic anisotropy on such inversion.

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Elastic stress driven rafting

During solid-solid phase transformations elastic stresses arise due to a difference in lattice parameters between the constituent phases. These stresses have a strong influence on the resultant microstructure and its evolution; more specifically, if there be externally applied stresses, the interaction between the applied and the transformation stresses can lead to rafting.

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Elastic fields of an edge dislocation

It is well known that the algebra associated with edge dislocations can be forbidding. As Prof. Frank (of the Frank-Read source fame) noted once,

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Some write-ups in mechanics

My googling today brought me to this treasure trove of write-ups in mechanics:

This site contains informal (usually rough draft) technical notes and tutorials on topics in mechanics. The sophistication is at the first or second year graduate level. These write-ups include:

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The SIAM 100-digit challenge of Bronemann et al: A review

Suppose if somebody asked you the following question, and more importantly, wanted the answer to an accuracy of 100-digits:

  • Problem A: A particle at the center of a 10 x 1 rectangle undergoes Brownian motion (i.e., two-dimensional random walk with infinitesimal step lengths) until it hits the boundary. What is the probability that it hits at one of the ends rather than at one of the sides?

Or, this question (again, demanding the answer to an accuracy of 100-digits):

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Some numerical mechanics software

Recently, during one of my net searches, I came across this page of RPI, where I learnt about a couple of numerical mechanics software which might be of interest to some of you.

FMDB:

As for the effort toward the scalable engineering simulations on distributed environements, we addressed this challenge by developing a distributed mesh data management infrastructure that satisfies the needs of distributed domain of applications.

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