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ErwanVerron's picture

Definition of a new predictor for multiaxial fatigue crack nucleation in rubber

From an engineering point of view, prediction of fatigue crack nucleation in automotive rubber parts is an essential prerequisite for the design of new components. We have derived a new predictor for fatigue crack nucleation in rubber. It is motivated by microscopic mechanisms induced by fatigue and developed in the framework of Configurational Mechanics. As the occurrence of macroscopic fatigue cracks is the consequence of the growth of pre-existing microscopic defects, the energy release rate of these flaws need to be quantified. It is shown that this microstructural evolution is governed by the smallest eigenvalue of the configurational (Eshelby) stress tensor. Indeed, this quantity appears to be a relevant multiaxial fatigue predictor under proportional loading conditions. Then, its generalization to non-proportional multiaxial fatigue problems is derived. Results show that the present predictor, which covers the previously published predictors, is capable to unify multiaxial fatigue data.

On the crack growth resistance of shape memory alloys

With the increasing use of shape memory alloys in recent years, it is important to investigate the effect of cracks. Theoretically, the stress field near the crack tip is unbounded. Hence, a stress-induced transformation occurs, and the martensite phase is expected to appear in the neighborhood of the crack tip, from the very first loading step. In that case, the crack tip region is not governed by the far field stress, but rather by the crack tip stress field. This behavior implies transformation toughening or softening.

Arash_Yavari's picture

On the geometric character of stress in continuum mechanics

This paper shows that the stress field in the classical theory of continuum mechanics
may be taken to be a covector-valued differential two-form. The balance laws and other funda-
mental laws of continuum mechanics may be neatly rewritten in terms of this geometric stress. A

Andrew Norris's picture

Free access to Computational Mechanics back to Vol 1 - but only 'til end of month.

Springer - in an attempt to get customers I suppose - are offering free access to the journal Computational Mechanics, but only for March 2007.

You can access all articles in Computational Mechanics back to vol 1/1, e.g. the first article

E. Reissner
Some aspects of the variational principles problem in elasticity
Volume 1, Issue - 1, First Page - 3, Last Page - 9
DOI - 10.1007/BF00298634
Link - http://www.springerlink.com/content/t52w761088542m68

To get the free access (for the rest of March) go to
http://scientific-direct.net/c.asp?id=650015&c=7fbfc8d9b40ac978&l=31

Rashid K. Abu Al-Rub's picture

Dr. Stelios Kyriakides’ election to the United States National Academy of Engineering

Dr. Stelios KyriakidesPlease joint me in congratulating Dr. Stelios Kyriakides’ (Editor of International Journal of Solids and Structures) for his election to the United States National Academy of Engineering.

zishun liu's picture

Computational Cancer Mechanics

Since Dec. 2006, Institute of High Performance Computing (IHPC) has set up a biophysics research team that comprises research scientists in the fields of biophysics, solid mechanics and fluid mechanics, and has kicked off the "Computational Cancer Mechanics" project.

What's wrong with the way we learn Applied Mechanics?

I was reading professor Zhigang Suo's post titled "What's Wrong with Applied Mechanics", thinking about the large amount of knowledge available. There are so many applications of mechanics that they seem endless in any subfield that one can think of. It made me recall some homework problems that wanted to include real life applications. However, real life applications tend to turn out much more complicated than what can be covered in one homework problem.

Zhigang Suo's picture

How to read new comments at a glance?

As the number of comments increases rapidly, how can anyone keep up? One answer is to use a RSS reader. The service is free, and takes 5 minutes to set up. It allows you to see all new comments at a glance, without clicking on individual ones. Once you have set up your Google Reader, paste the URL for the feed of comments crss

Ravi-Chandar's picture

Movie of an expanding ring experiment

I have posted a movie showing a ring expansion experiment. A thin aluminum ring is made to expand through electromagnetic interaction at strain rates of about 10^4 per second. As the strain increases, numerous necks and fragments appear.

Mahdi Kazemzadeh's picture

"iMechanica",Promotes the "Education"??

Choose a channel featured in the header of iMechanica: 

Let's contribute in a bit more educational topic!! If I want to mention two unique properties of the iMechanica, I can say iMechanica is a place where an alive discussion about popular topics of the mechanics going on every day and non stop. So this improves new ideas and as a consequence build some platforms for future research topics in the mechanics world. For me as an student, there is another beneficial and that is some courseworks or lecture notes which I download regularly. These handouts prepared by very expert scientists and are so useful. I appreciate this activities and I am very grateful to all people who also update the educational part of the webpage. Here is a new topic which with your help and comments can improve this part more and give it serious role to play here. Would you write about the summer schools which you are going to have in your universities and institutes located all over the world this summer? The summer schools is a point of interest among all students, specially if the topic will be about mechanics, modelling and simulation, nanomechanics and specially biomechanical issues. Also I will be very pleased if you will recommend the conferences you are going to hold or you like to introduce to student's section. That is another point which will be very useful. I am sure that it will be interesting for other members also. I am waiting for all your helps and news about "summer schools" and other "educational activities" running by you or your universities. I wish you all the best. Thank you.   

Chwee Teck Lim's picture

GEM4 Summer School on Cell & Molecular Mechanics in Biomedicine 2007, Singapore - 25 June to 6 July 2007

Dear friends and colleagues,

We will be organizing a GEM4 Summer School on Cell & Molecular Mechanics in Biomedicine (with a focus on Cancer) at the National University of Singapore from 25 June to 6 July 2007. It will also be held in conjunction with the GEM4 Conference on Cancer to be held from 1 to 6 July 2007.

Mike Ciavarella's picture

Italian stress analysis AIAS conference in Ischia --- call for papers Sept.

dear Imechanica users,

a wonderful location for our annual italian conference in stress analysis -- see www.aias2007.it. It is organized by our collegues in Università di Napoli, Prof. Renato Esposito. Attached the call for papers in PDF, and more info are below.

Floating ships of ice and increasing the toughness of glass

http://en.wikipedia.org/wiki/Project_Habakkuk

I was surprised several years ago when delving into the literature to not find any references about addition of nanoparticles to ice, to study their impact on the mechanics of ice.  In short, to make nanocomposites where the matrix is ice.  So, with 2 high school students from IMSA, the Illinois Math and Science Academy, we set about (with their limited time for a bit of research) to try adding some nanoparticles to water and to freeze it.  The students simply used their home freezers to do this, and their mechanics measurements were with a hammer and chisel...

Simpleware signs up reseller in China

Simpleware Ltd., the world leader in image-based meshing software, has signed an agreement with Gaitech International Ltd. to resell the Simpleware suite of software products in China, Hong Kong, Taiwan and Macao.

Simpleware software offers an advanced solution to problems that were previously intractable due to the complexity in geometry reconstruction. Simpleware's technology has opened up numerical analysis (CFD and FEA) to a variety of applications, including biomedical engineering, material characterisation and industrial reverse engineering.

jfmolinari's picture

A new methodology for ranking scientific institutions

 

We extend the pioneering work of J.E. Hirsch, the inventor of the h-index, by proposing a simple and seemingly robust approach for comparing the scientific productivity and visibility of institutions. Our main findings are that i) while the h-index is a sensible criterion for comparing scientists within a given field, it does not directly extend to rank institutions of disparate sizes and journals, ii) however, the h-index, which always increases with paper population, has an universal growth rate for large numbers of papers; iii) thus the h-index of a large population of papers can be decomposed into the product of an impact index and a factor depending on the population size, iv) as a complement to the h-index, this new impact index provides an interesting way to compare the scientific production of institutions (universities, laboratories or journals).

Zhigang Wei's picture

Any suggestion for a fast sparse solver

It seems that a customized FEM code is always necessary for special research purposes. In our group we use a home-made FEM code to simulate arbitrary crack growth in 3D domain with nodal release or re-meshing.

Rui Huang's picture

Thin films: wrinkling vs buckle-delamination

H. Mei, J.Y. Chung, H.-H. Yu, C.M. Stafford, and R. Huang, Buckling modes of elastic thin films on elastic substrates. Applied Physics Letters 90, 151902 (2007).

Two modes of thin film buckling are commonly observed, one with interface delamination (e.g., telephone cord blisters) and the other with no delamination (i.e., wrinkling). Which one would occur for your film?

Joost Vlassak is promoted to Full Professor with Tenure at Harvard

Joost J. Vlassak's pictureWe have just heard the great news that our colleague (iMechanician number 12), Joost Vlassak, has been promoted to Full Professor with Tenure at Harvard.

A new type of bubble raft--challenge for clever students

17 years ago, while a postdoc at IBM meant to be doing other things, I thought about the following. Then recently I visited Ali Argon at MIT, and we discussed conventional bubble rafts and how useful they had been in studies of some problems in mechanics...such as of defects and so on.

Quantum Confinement Induced Strain in Quantum Dots

In the attached pre-print, we investigate quantum confinement induced strain in quantum dots. This paper has been written keeping in mind the condensed matter physics/quantum dot community (accepted for publication in Phy.

L. Roy Xu's picture

A pool filled with non-newtonian fluid

They filled a pool with a mix of cornstarch and water made on a concrete mixer truck. It becomes a non-newtonian fluid. When stress is applied to the liquid it exhibits properties of a solid. Video was recorded at Barcelona, Spain.

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