Several recent papers have reported measurements of adhesion energy between graphene and other materials (e.g., Si/SiOx and copper) [1-3]. Like thin films, many experimental methods may be adopted to measure the interfacial properties of graphene, such as the pressurized blister test [2] and the double-cantilever beam test [3]. The challenges lie in the handling of atomically thin membranes and analysis/interpretation of the data.

Delivered by Ingenta to:
University of Southern California
IP : 132.174.255.3
Sun, 29 Jul 2012 00:05:58
Contact deformation can cause local damage of mechanical structures and lead to structural failure
of mechanical devices. In this work, we use the finite element method to analyze the indentation-
induced delamination of a film-substrate structure and the critical tensile stress as the criterion to
determine local delamination on the interface between the film and the substrate. The simulation
results show that both the size of the delamination zone and the maximum separation increase
with increasing the indentation depth and with decreasing the film thickness. The delamination also

the red part is the interface element

I'm doing Mtech project on Finite Element Modeling On Polymer Nanocomposite with Clay Nanofiller.  For that am using ABAQUS software,  so i need some information regarding that ABAQUS software, how to do finite element modeling of nanocomposites with nanofiller and How to prepare a code distrubution in the plate like particales in the polymer matrix with ABAQUS software. So please can any give information.

A postdoctoral associate position at MIT is available immediately,
focused on the analysis and development of multifunctional thermal
management structures, by using theoretical and atomistic multiscale
modeling and simulation. This project specifically involves calculations
of thermal and mechanical properties of graphene based metal- and
polymer nanocomposites, with a focus on various aspects such as
interfacial transport properties, tunability, mutability and phonon
engineering. Additional aspects of the project relate to the general
area of mechanical energy transport in biological materials.

Hello,

(for completing R. Huang's post : http://imechanica.org/node/7396).

A  few years ago, some colleages (from Italy, UK and Brazil) and I proposed some comparisons of the behavior of cohesize zone models. This was presented during ECCM 2004. The paper is attached.

Hi,
I am working on effects of Blast Loading in sandwich composites using Abaqus. I want to incorporate Cohesive behaviour at the interface of the two materials in the sandwich composite structure i am analysing.

 When I specify the interaction proporty as a cohesive bahaviour(if i dont intend to use thedefault parameters given by Abaqus), I am supposed to input whether its coupled interaction or uncoupled interaction and inpur the relevant values of Knn, Ktt, Kss etc. As of now, I am not able to find any standard literature values available for these contants on the internet. So I've been using the defaults given by Abaqus.

Hi everybody,

do you know where I can find some informations about the relation

between particle size and critical normal stress at the interface particle /matrix

for a particle embedded in a matrix?

I read the Chen's article 'Size effect of particles on the damage dissipation in nanocomposites'

but this article deals with spherical particles. I am studying clay/matrix nanocomposites and I would like to

calculate the relation between clay size and debonding stress.

Thanks,

Cecilia

I am Cecilia. In 2007 I graduated in mechanical engineering at the University of Cagliari (Sardinia, Italy).

Hi,

I am simulating failure of concrete in tension and compression on a concrete representative element volume. I have modeled mortar matrix and aggregate (inclusion) separately i.e my model consists of two material and assumed them as perfectly bonded. My question is, if I add interface zone between matrix and inclusion how will it effect my overall failre or can I neglect inerface.

With Warm Regards

Gouse

H. Mei, Y. Pang, and R. Huang, International Journal of Fracture 148, 331-342 (2007).

Following a previous effort published in MRS Proceedings, we wrote a journal article of the same title, with more numerical results. While the main conclusions stay the same, a few subtle points are noted in this paper.

First, instead of using the approximate formula by Ye, Suo and Evans (1992), we calculate the energy release rate of interfacial delamination emanating from the channel crack exclusively by the finite element method. We found that the approximate formula is not accurate in several cases.

Many people here are interested in the behaviours of interfaces.

I am interested in having a list of the cohesive energy for interfaces between different materials, such as polymer/ceramics, polymer/metals, polymer/polymer, metals/ceramics, biological interfaces, carbon nanotube/polymer matrix, etc.

So, what is the magnitude of the cohesive energy per unit area of the interface you are studying?
 

The programme for the 28th Risø International Symposium on Materials Science has now been finalized (see http://www.risoe.dk/Conferences/symp28/programme.aspx ).

 The Symposium is held at Risø National Laboratory, The Technical University of Denmark, 3-6 September 2007. 

 To sign up for the conference, please register up via the Symposium homepage: http://risoe-forms.risoe.dk/RISMS/RISMS_registration.asp  

Before we start this issue of J-club, I would like to recommend Prof. Langer's lecture for his MRS Von Hippel Award in the 2005 MRS Fall Meeting (Langer, 2006). His lecture not only delineated the history of the new exciting field of drug delivery and controlled release, but also told us many interesting stories happened in his career development. With Prof. Langer's pioneer work, many new materials are developed for designing new drug delivery and controlled drug release systems.

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.

Hi All,

Are there any good references showing the detailed derivations of elastic strain energy release rate using J-integral instead of differentiating compliance for end notch beam samples : DCB, 3/4 point bend ...? many thanks ...

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.

When I was a graduate student, I spent several months to measure interfacial toughness between metalic (Cu and Au) films and thick substrates(Si and Polycarbonate). My methods were bulge test (blistering test) and 4-point bending test. I had many problems such as making an initial crack(pre-cracking), changing load phase angle applied to specimens, preparing/patterning thin films, constructing my own test apparatus, etc. The biggest problem was to measure the interfacial toughness over a wide range of loading phase angle. For a bimaterial with a non-zero oscillatory index(epsilon), we don't know the phase angle for a minimum interfacial toughness beforehand. Therefore, we need to measure the interfacial toughness over a wide range of phage angle. For engineering purpose, we need a minimum interfacial toughness value for reliability design because this value will lead to a conservative design of systems.

Zhen Zhang and Zhigang Suo

For a crack impinging upon a bimaterial interface at an angle, the singular stress field is a linear superposition of two modes, usually of unequal exponents, either a pair of complex conjugates, or two unequal real numbers. In the latter case, a stronger and a weaker singularity coexist (known as split singularities). We define a dimensionless parameter, called the local mode mixity, to characterize the proportion of the two modes at the length scale where the processes of fracture occur. We show that the weaker singularity can readily affect whether the crack will penetrate, or debond, the interface.