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.
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 hope you can take the opportunity to network in Sitges with people of similar research interests at this informative and well-received single-stream conference.
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.
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.
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.
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
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.
Are not as high as we expected although very stiff and strong nanotubes or nanofibers (Young’s modulus E~1000GPa) are added into soft polymer matrices like epoxy (E~4GPa).In our early investigation on the systematic mechanical property characterizations of nanocomposites (Xu et al., Journal of Composite Materials, 2004--among top 5 in 2005;and top 10 in 2006 of the Most-Frequently-Read Articles in Journal of Composite Materials.) have shown that there was a very small increase (sometimes even decrease) of critical ultimate tensile/bending strengths, and mode-I fracture toughnesses in spite of complete chemical treatments of the interfacial bonding area, and uniform dispersions of nanofibers (click to view a TEM image). Similar experimental results were often reported in recent years. Therefore, mechanics analysis is extremely valuable before we make these “expensive” nanocomposite materials. Our goal is to provide in-depth mechanics insight, and future directions for nanocomposite development. Till now, nanocomposite materials are promising as multi-functional materials, rather than structural materials. Here we mainly focus on two critical parameters for structural materials: tensile strength and fracture toughness. We notice that other mechanical parameters such as compressive strengths and Young’s moduli of nanocomposite materials have slight increase over their matrices.
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