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Coupling meshfree and Finite element methods

Submitted by Rajathachal.MK on

I just wanted to know if i can consider one part of a FE model as a meshless part and form the global stiffness matrix just by assembling the meshfree stiffness matrix corresponding to the meshfree zone and the FE stiffness matrix of the rest. And then apply the boundary conditions to the model and solve. I would use RKPM to generate the meshfree stiffness matrix. 

Journal Club Theme of 1 May 2008: Mechanical Behaviors of Polymer-matrix Nanocomposites

Submitted by L. Roy Xu on
Choose a channel featured in the header of iMechanica

1. Definition of nanocomposites Nanocomposites are a novel class of composite materials whose reinforcements have dimensions in the range of 1-100 nm. Although nanoscale reinforcements (or nanofillers) of nanocomposites have different kinds of fillers such as nanofibers, nanowires, nanotubes and nanoparticles etc, their mechanical behaviors have some common features.

Large deformation elasticity and damping of individual carbon nanotubes in radial direction

Submitted by Majid Minary on

Carbon nanotubes as strong fibers in CNT-composites are subjected to large deformations in radial direction. They provide strength as well as structural damping in the composite. Despite being strong in the axial direction, CNTs are rather soft in the radial direction.

Challenges in modeling of CNT/polymer composites

Submitted by Kazem Yazdchi on

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.

lack of sensitivity

Submitted by adelajda on

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 

The 2008 Melosh Medalists

Submitted by John E. Dolbow on

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.  

Poisson's ratio changable of carbon nanotube sheet

Submitted by Ying Li on

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

Crack Propagation using XFEM ( What happens to dof's corresponding to enriched nodes)

Submitted by Kapil.Nandwana on

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?