Fundamentals of Micromechanics of Solids, Jianmin Qu, Mohammed Cherkaoui
ISBN: 0-471-46451-1, Hardcover, 400 pages, August 2006, US $120.00

PART I: LINEAR MICROMECHANICS AND BASIC CONCEPTS

Chapter 1 INTRODUCTION

• 1.1 Background and Motivation
• 1.2 Objectives
• 1.3 Organization of Book
• 1.4 Notation Conventions
• References

Chapter 2 BASIC EQUATIONS OF CONTINUUM MECHANICS

GRIFFITH AA, The phenomena of rupture and flow in solids. Philosophical Transactions of the Royal Society of London, Sereis A, 221:163-198, 1921.

The Eighth International Conference on Fundamentals of Fracture (ICFF VIII) is the successor of the previous seven held at NBS, Gaithersburg (USA, 1983), Gatlinburg (USA, 1985), Irsee (Germany, 1989), Urabandai (Japan, 1993), NIST, Gaithersburg (USA, 1997), Cirencester (UK, 2001), and Nancy (France, 2005). You are warmly invited to participate in ICFF VIII which will be held 3-7 January 2008 in Hong Kong University of Science and Technology, Hong Kong, and in Guangzhou, China. As the previous conferences, ICFF VIII provides an international forum for presentation and discussion of the latest scientific and technological development in fundamentals of fracture. The general theme of ICFF VIII is to cover all aspects of fracture at a fundamental level, including contributions from those working in the disciplines of Continuum Mechanics, Physics, Chemistry, Bioscience, Metallurgy, Ceramics, Polymer Science, etc. You are cordially invited to submit an abstract to join in this memorable event.

Anyone interested in the history of mechanical technology might find interesting the series that I have published in Mechanical Engineering magazine.

Galileo’s Telescope Lenses

http://www.memagazine.org/oct06/features/clearas/clearas.html

Atmospheric Railway

http://www.memagazine.org/backissues/feb06 /features/tallyho/tallyho.html

As you know, the volumetric expansion by 9% during the water-to-ice transition can generate tremendous pressure in a confined space is a common sense. As a result, one may expect freezing water to also fracture rocks.

However, in a recent article in Science, Bernard Hallet explains the power of the 9% water-to-ice expansion in confined spaces is undeniable, but it may rarely be significant for rocks under natural conditions, because it requires a tight orchestration of unusual conditions. Unless the rocks are essentially saturated with water and frozen from all sides, the expansion can simply be accommodated by the flow of water into empty pores, or out of the rock through its unfrozen side.

I think it may be of interest to mechanics. Read more
I hope to hear opinions from people who know about the breaking mechanics of rocks.

This is a paper we recently published in JMPS on a study of the mechanical properties on thin films comparing experimental results with discrete dislocation simulations. It provides insight in the strengthening that occurs in thin metal films when surface or interface effects become important.

The abstract is below; the full paper can be downloaded from here

Abstract - Experimental measurements and computational results for the evolution of plastic deformation in freestanding thin films are compared. In the experiments, the stress–strain response of two sets of Cu films is determined in the plane-strain bulge test. One set of samples consists of electroplated Cu films, while the other set is sputter-deposited. Unpassivated films, films passivated on one side and films passivated on both sides are considered. The calculations are carried out within a two-dimensional plane strain framework with the dislocations modeled as line singularities in an isotropic elastic solid. The film is modeled by a unit cell consisting of eight grains, each of which has three slip systems. The film is initially free of dislocations which then nucleate from a specified distribution of Frank–Read sources. The grain boundaries and any film-passivation layer interfaces are taken to be impenetrable to dislocations. Both the experiments and the computations show: (i) a flow strength for the passivated films that is greater than for the unpassivated films and (ii) hysteresis and a Bauschinger effect that increases with increasing pre-strain for passivated films, while for unpassivated films hysteresis and a Bauschinger effect are small or absent. Furthermore, the experimental measurements and computational results for the 0.2% offset yield strength stress, and the evolution of hysteresis and of the Bauschinger effect are in good quantitative agreement.

It is well-recognized that MEMS switches, compared to their more traditional solid state counterparts, have several important advantages for wireless communications.  These include superior linearity, low insertion loss and high isolation.  Indeed, many potential applications have been investigated such as Tx/Rx antenna switching, frequency band selection, tunable matching networks for PA and antenna, tunable filters, and antenna reconfiguration. 

However, none of these applications have been materialized in high volume products to a large extent because of reliability concerns, particularly those related to the metal contacts.  The subject of the metal contact in a switch was studied extensively in the history of developing miniaturized switches, such as the reed switches for telecommunication applications.  While such studies are highly relevant, they do not address the issues encountered in the sub 100mN, low contact force regime in which most MEMS switches operate.  At such low forces, the contact resistance is extremely sensitive to even a trace amount of contamination on the contact surfaces.  Significant work was done to develop wafer cleaning processes and storage techniques for maintaining the cleanliness.  To preserve contact cleanliness over the switch service lifetime, several hermetic packaging technologies were developed and their effectiveness in protecting the contacts from contamination was examined.  

Stresses inevitably arise in a microelectronic device due to mismatch in coefficients of thermal expansion, mismatch in lattice constants, and growth of materials. Moreover, in the technology of strained silicon devices, stresses have been deliberately introduced to increase carrier mobility. A device usually contains sharp features like edges and corners, which may intensify stresses, inject dislocations into silicon, and fail the device. On the basis of singular stress fields near the sharp features, this letter describes a method to obtain conditions that avert dislocations.

In a recent article in Physical Review Letters, Alain Goriely and Sébastien Neukirch offer a mechanical model of how the free tip of a twining plant can hold onto a smooth support, allowing the plant to grow upward. The model also explains why these vines cannot grow on supports of too large a diameter. Read more.

The mechanics involves large deflection and bifurcation of a rod. I hope to hear opinions from people who know about the mechanics of plants.