research

Many researchers have already used micromechanical modeling techniques such as Mori-Tanaka (M-T), Self-consistent methods and dilute inclusion models depending on volume fraction and shape of the inclusions, etc., to predict the overall mechanical properties of CNT/polymer composites.  However, we know that at nano scales the phenomenological behavior of material is different in comparison with micro or macro scales. Although the effects of waviness, interactions, agglomeration, etc.

Hi everybody.  My name is Ada. I am a new user on this forum.

I am working with microcantilevers (MCs). Recently I experienced lack of sensitivity. I use  MCs coated with nanostructured gold and I use SAM to attach different biological molecules e.g. Protein A, IgG, antiIgG. Everything was working fine until recently.

Would enybody have any sugestions what might be wrong?

Thanks,

Ada 

On Friday, April 25th, 2008, the 20th Annual Melosh Competition for the Best Student Paper in Finite Element Analysis was held at Duke University.  The competition resulted in a tie between Ludovic Chamoin (of the University of Texas, Austin) and Irina Kalashnikova (of Stanford University).   Here is a picture of the 2008 Melosh Medalists with the judges, Leo Franca and Nicolas Moes:

 From L to R: Leo Franca, Ludovic Chamoin, Irina Kalashnikova, Nicolas Moes.  

Here is a recent work on the Poisson's ratio of carbon nanotube sheet [1]. From the experimental results, the researchers found that the Poisson's ratio could change from 0.06 to -0.20 as the content of MWNTs increasing from 0~100%. The interesting zero Poisson's ratio and auxetic materials were thus found.  

Ref. [1] Sign Change of Poisson's Ratio for Carbon Nanotube Sheets. Science 25 April 2008: 504-507

Ying Li

Department of Engineering Mechanics, Tsinghua University

I am working on crack propagation . I am trying to figure what factors should be taken into account when the crack is being propagated using XFEM.

I am especially interested to know what happens to the additional dof's corresponding to enriched nodes. Once the crack is propagated and crack tip is at new location , we add new dof's corresponding to enrichment functions , but what happens to the information stored by the dof's of previous enriched nodes,do we forget them altotgether , or do we map it to the new enriched nodes?