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Rashid K. Abu Al-Rub's picture

Strain Gradient Plasticity

Recently, there have been many strain gradient theories that are used for the interpretation of size effect at the micron and submicron length scales. The basic idea of these theories is the introduction of a first, or second (or both) gradients of strain or any internal state variable in the governing equations of classical theories.

The development of Crystal plasticity

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Recent experiment have shown the size effect of the materials, when the characteristic length associated with non-uiform plastic deformation is on the scale of micros.The classic plasticity theories can't explain such phenomenon as their constitutive models posses no intrinsic length scale. The new models which contain strain gradient plasticity now are used to explain the experiment.

Henry Tan's picture

Instabilities in Material Behaviors

The linked two of my studies can be used as references for Zhigang’s lecture on Instabilities.

(1) Catastrophic fracture

The 2007 Melosh Medalists

The 19th Annual Melosh Competition for the Best Student Paper in Finite Element Analysis was held last Friday, April 27, at ETH Zurich. Two medalists were selected this year from the six finalists. The 2007 Melosh Medalists are Vikram Gavini, from Caltech, and Michael Hain, from Leibniz University, Hannover.

Marko Davidovic's picture

XFEM in fluid saturated medium

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Hello! 

To describe the crack propagation in a fluid saturated solid I have idea

to combine the Strong Discontinuity (XFEM) with the fluid, but at the micro-scale, which probably means to use (Navier-)Stokes equations or some modification of them.

Marko Davidovic's picture

XFEM in fluid saturated medium

<>To describe the crack propagation in a fluid saturated solid I have idea to combine the Strong Discontinuity (XFEM) with the fluid, but at the micro-scale, which probably means to use (Navier-)Stokes equations or some modification of them. <>

Akbar Afaghi's picture

Thermal Diode

Hi everyone,

We are looking for the practical solutions for building a thermal diode using nanocomposites. A thermal diode allows the heat flow from one end to the other, but it inhibits the flow in the opposite direction. There are some simulations and theoretical work in this regard. Does anyone know any experimental work related to this matter? Thanks.

Xiaodong Li's picture

Journal Club Theme of May 2007: Experimental Mechanics of Nanobuilding Blocks

Welcome to the May 2007 issue. This issue focuses on experimental nanomechanics of nanobuilding blocks. The extremely small dimensions of nanobuilding blocks (for instance, nanoparticles, nanotubes, and nanowires) have imposed great challenges to many existing instruments, methodologies, and even theories.  In this issue, we will discuss – (1) experimental techniques and (2) size-effects. 

Super stretchy carbon nanotubes

Huang et al., PRL 98, 185501 (2007)

Watch movies at: http://netserver.aip.org/cgi-bin/epaps?ID=E-PRLTAO-98-002719

We report exceptional ductile behavior in individual double-walled and triple-walled carbon nanotubes at temperatures above 2000 C, with tensile elongation of 190% and diameter reduction of 90%, during in situ tensile-loading experiments conducted inside a high-resolution transmission electron microscope. Concurrent atomic-scale microstructure observations reveal that the superelongation is attributed to a high temperature creep deformation mechanism mediated by atom or vacancy diffusion, dislocation climb, and kink motion at high temperatures. The superelongation in double-walled and triple-walled carbon nanotubes, the creep deformation mechanism, and dislocation climb in carbon nanotubes are reported here for the first time.

Henry Tan's picture

Surface roughness evolution

With a shallow chemical etching the roughness with spatial frequency below a critical value grows while the roughness of higher frequency decays.

node/1312

Henry Tan's picture

Surface roughness evolution

Surface roughness evolution in frequency domain.
node/1313

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Aerodynamics/CFD research

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Hi,

i am a student of mechanical engg from india . Am a aerodynamics/computational enthusiast .

can someone tell me what are the current research topics in this field ..

MichelleLOyen's picture

Adhesion in viscoelastic contacts

Yesterday I had the distinct pleasure of seeing a mechanics seminar delivered "tag-team" by Ken Johnson and Jim Greenwood. (I know several people have thought I was a bit mad for jumping "across the pond" but there are really some amazing benefits of being part of the Cambridge Engineering faculty!)

Xuejun Fan's picture

Adhesion study for polymer/polymer interface or polymer/metal interface in microscopic level

Is there any study on hierarchical structures for polymer/polymer interface or polymer/metal interface? and link the polymer molecular structure with fracture or adhesion study? What is the role of mechanical bonding compared to physical and chemical bonding?

Micropolar material constants

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Can someone help me to give the numerical values for micropolar elastic solids and micropolar fluids so that i can study the behaviour of such materials numericaly?  Also suggest me some references and books regarding Micropolar Elasticity. 

Micropolar material constants

Can someone help me to give the numerical values for micropolar elastic solids and micropolar fluids so that i can study the behaviour of such materials numericaly?  Also

Microcantilever operated in liquid environment for in-vitro biomolecular detection

We have recently reported the piezoelectric thick film microcantilever, which enables the in-situ real-time detection of the protein related to disease (e.g. C reactive protein) in liquid environment. This work was published at APL (click here).

"In-situ real-time monitoring of biomolecular interactions based on resonating microcantilevers immersed in a viscous fluid"

Henry Tan's picture

POLYMER MATRIX COMPOSITES REINFORCED BY CARBON NANOTUBES

CONTINUUM MODELING OF INTERFACES IN POLYMER MATRIX COMPOSITES REINFORCED BY CARBON NANOTUBES

L. Y. JIANG, H. TAN, J. WU, Y. HUANG, K. -C. HWANG
Review Article, 2007, accepted by NANO

The interface behavior may significantly influence the mechanical properties of carbon nanotube (CNT)-reinforced composites due to the large interface area per unit volume at the composite. The modeling of CNT/polymer interfaces has been a challenge in the continuum modeling of CNT reinforced composites.

Henry Tan's picture

carbon nanotube-reinforced composite materials

The effect of van der Waals-based interface cohesive law on carbonnanotube-reinforced composite materials

H. Tan, L. Y. Jiang, Y. Huang, B. Liu, and K. C. Hwang
Composite Science and Technology, 2007, accepted.

Amit Acharya's picture

papers related to reply: apparent randomness continues

Two papers are attached related to randomness discussion.

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