The  Paris equation should correctly be referred to as the ERDOGAN-PARIS equation, maybe some more names may be needed.

LEFM is a term bandied about in the text books, but very few texts  know how to define what it means and how it applies.

You can take my course.  What happened to the earlier posts about my course.

Anyone who contributes to my DORN-RAJNAK or HARPER DORN will be given credit.

kfupm.edu.sa/publications/ajse/articles/3318_P.18.pdf

A postdoctoral associate position at MIT is available immediately, focused on elucidating the fundamental material science concepts that control the formation, behavior and in particular mechanical failure and fracture of fibrous amyloid protein materials. Amyloids form pathogens in diseases (Alzheimer’s, Parkinson’s), play a role in defining the properties of spider silk, and are found in many natural adhesives. These beta-sheet rich protein structures constitute an intriguing class of protein materials that self-assemble at room temperature to form characteristic hierarchical nanostructures and fibers, which combine exceptional strength and sturdiness, elasticity with bioactivity and the ability to self-heal. 

I have read some papers about fracture mechanics of functionally graded materials. I find there are different results for the stress intensity factors when the crack length is close to "0" . In some papers the values of stress intensity factors are "1" when the crack length is close to "0" , but in other papers the values of stress intensity factors are not "1". I obtain the stress intensity factors is "1" when the length of crack is close to "0". I hope to get the explaination about the results.Thanks a lot.

Ferroelectric materials have seen applications as actuators (the fuel injection system in the latest BMWs), sensors (naval sonar systems), and ferroelectric nonvolatile random access memories (FRAMs). For actuators and sensors it is the piezoelectric behavior of these materials that is exploited, while for FRAMs the ability of the material to “switch” polarization states is the essential feature for the application. 

The Australian Mineral Science Research Institute (AMSRI) is a consortium of Australia's best scientists working in minerals industry-related fields. Research activities span the breadth of minerals processing, with major themes of the research being energy efficiency, frugal water use and efficient management of waste. The Mathematics program of AMSRI performs modelling and analysis research across multiple minerals processing areas, including comminution, flotation and waste treatment.

Integrating porous low-permittivity dielectrics into Cu metallization is one of the strategies to reduce power consumption, signal propagation delays, and crosstalk between interconnects for the next generation of integrated circuits. However, the porosity and pore structure of these low-k dielectric materials also strongly affects other important material properties besides their dielectric constant.

PhD available at the University of Glasgow entitled ‘Numerical Simulation of Fault Evolution in Oil Reservoirs’ 

EPSRC Case Award with Schlumberger - £15,500 per annum + fees. 

http://dx.doi.org/10.1016/j.ijfatigue.2008.03.004

Hi iMechanica,

  I am not sure if I can post this type of primitive questions here, but hope you wouldn't mind.  I have a 1'' by 3'' mica sheet, and it needs to cut hopefully without cracks. I searched on available papers but could not find one that described how a cut with hot-wire configuration was made of. (closest call was "Platinum Nanoparticles at Mica Surfaces" by Zhiqun Lin and Steve Granick). If you have an experience on cutting mica for your research, could you please share with me about how you set up cutting tools or another simpler method?  I have a platinum wire (d = 0.2mm), but do not have anything else at this moment.

 Sincerely,

 Masa

Hello! 

As a student who has spent a lot of time studying cohesive zone models in fracture mechanics, I have several questions that have bothered me over the past year or so, and I have not been able to find suitable answers to them. I am limiting myself here to questions related to the traction-separation law, which invariably forms the basis of CZM as it is implemented today. I am raising these questions in the hope that I can receive some response here, even if it means my question is invalid (as I suspect a few may be).  So here is my list:

----- 

B. Li, M. K. Kang, K. Lu, R. Huang, P. S. Ho, R. A. Allen, and M. W. Cresswell, Nano Letters 8, 92 -98 (2008). (Web Release Date: 07-Dec-2007; DOI: 10.1021/nl072144i)

I'm studying cracking analyses in a three point loaded specimen of a composed beam.I'm using ANSYS and i want to create codes for estimation of J integral and energy release rate in the vicinity of crack tip.After that i'll calculate the stresses and strains fields,and then i can compare the equivalent fields i retrived using CTOD  and K(I,II,III) factors (according to ANSYS algorithm).

My problem is that I'd like to find a relationship between the above mentioned quantities(J,G)  with K(I,II,III)factors.

The abstract submission deadline for this next conference in the biennial Engineering Failure Analysis series (www.icefa.elsevier.com) is 30 November 2007.

The conference will take place in the coastal town of Sitges, just a short distance from Barcelona's international airport, from 13 to 16 July 2008.    

I am trying to implement quasi static fracture in a discrete lattice model, with material being viscoelastic. Do i need to use an incremental-iterative method? Please give your suggestions.

I am a Ph.D. student in Department of Solid Mechanics at Xian Jiao-Tong University, P.R. China.

My research interests include Fracture Mechanics of Piezoelectric Materials and Mechanics and Strength of Advanced Materials.

Most fracture classes and texts focus on the following different approaches: Griffith's energy approach, Irwin's stress intensity factor approach, the Barenblatt-Dugdale strip yield model (and subsequently, cohesive zone modeling) and Rice's J-Integral approach. As a graduate student studying fracture mechanics, I have often wondered why there seems to be very little discussion in the community with regard to Sih's strain energy density approach. Are there any fundamental limitations to the approach or are there "other" reasons behind this? Your thoughts are appreciated.

Thanks,
Dhruv 

hello

i am doing M.tech. i wanted to my destertation in improving the strenght of refractory material. so please guide me what is rectent on this topic...

It seems there are quite a few experimental studies [1,2] on the fracture properties of porous materials, like nanoporous low-k dielectrics, as a function of porosity. Can anyone point out some references on the theoretical part, like the available models, computational methods or analytical approaches that can capture microstructure information, including porosity, pore geometry etc. Interface delamination of porous materials is also of interest. Thanks.

Dr. Stewart Silling has provided me with a copy of his talk on Peridynamic theory that he presented at McMat 2007.  The PDF file of the talk is attached below.

In order to deal with classical material models and volume constraints, Dr. Silling has modified the original theory to allow for forces that are not necessarily pairwise. A bit on that is included in the talk.

You can find more information on peridynamics including a bit on Dr. Silling's code (EMU) at  http://www.sandia.gov/emu/emu.htm (though it's slightly out of date).  Dr. Silling promises to update the site in the near future.

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...

There have been several posts recently discussing new directions in computational mechanics. Here is a review article that appeared recently that may be of interest.

Large-scale hierarchical molecular modeling of nanostructured biological materials

an interesting puzzle for fun:

Lame’s classical solution for an elastic 2D plate, with a hole of radius a and uniform tensile stress applied at the far field, gives a stress concentration factor (SCF) of two at the edge of the hole. This SCF=2 is independent of the hole radius.

Consider what happened to this concentration factor if the radius a approaches infinitely small. The SCF is independent of a, so it remains equal to two even when the hole disappears.

This is inconsistent with what one would expect physically, namely that the limit a->0 should be the same as when the plate is whole without a hole and has no stress concentration.

Henry.