iMechanica

As we know, lattice boltzmann method is one method to solve the fluid problems. and the primary work to use this method is give the corrected "boundary conditon"__pressure conditions and velocity conditions.

To general problems, the PC and VC for 2D/3D problems has been obtained by some scientists(eg.D3Q19,D2q9 ...model).

But to the lowest scale problems, the "force" fields is complexed and the traditional PC/VC is not suit for this kind of problems.

My opinion:

I have a question regarding the experimental determination of rate independent phenomenological elaso plastic constitutive model.

Since the models are rate independent, does the strain rate in the experiments used to calibrate the model parametes have any influence on the model. I am talking about this in context to the Cap plasticity model used in Abaqus. One has to run a certain number of powder compaction experiments to calibrate the model.

I have a fundamental question regarding flow rules of finite plasticity models especially those used in soil mechanics. In most of the papers and books, I have seen the usage of an associated flow rule with the plastic potential similar to the yield surface. However, I am unable to understand the means of obtaining a non-associative flow rule. I am using Abaqus with cap plasticity model (modified Drucker Prager Cap model) to simulate powder compaction process.

Research on multiscale stochastic modeling is becoming big. In this article "A Green-function-based multiscale method for uncertainty quantification of finite body random heterogeneous materials"  doi:10.1016/j.compstruc.2009.05.009 , one of the first multiscale stochastic methods is developed for solid mechanics applications.....    

For a flexible electronic device integrating inorganic materials on a polymer substrate, the polymer can deform substantially, but the inorganic materials usually fracture at small strains.  This paper describes an approach to make such a device highly stretchable.  A polyimide substrate is first coated with a thin layer of an elastomer, on top of which SiNx islands are fabricated.  When the substrate is stretched to a large strain, the SiNx islands remain intact.  Calculations confirm that the elastomer reduces the

A postdoctoral research fellow position is currently open in the Computational Nanomechanics group at the University of Pittsburgh for the following research projects in the multidisciplinary areas of computational nanomechanics, nanotechnology, renewable energy, and nanomedicine: 

1. Hydrogen and bio-sensing nanowire fabrication

 dear everyone,

I want to ask if anyone deal with strain gradient proposed

by fleck eat. in 1994 and 1997, using subroutine in ABAQUS ?

Hi everybody,

I modeled a sheet metal forming process in which entire blank is partitioned into two regions (Central and exterior regions). Forming tool is considered as a 3D-Analytical rigid body (Revolved Shell) and partitioned into two regions too. According to this process, the head of punch should be tied to the central region of the blank and punch's walls should contact with exterior region.

In a lithium-ion battery, both electrodes are atomic frameworks that host mobile lithium ions. When the battery is being charged or discharged, lithium ions diffuse from one electrode to the other. Such an insertion reaction deforms the electrodes, and may cause the electrodes to crack. This paper uses fracture mechanics to determine the critical conditions to avert cracking. The method is applied to cracks induced by the mismatch between phases in crystalline particles of LiFePO4

Programs from Programming the Finite Element Method by Ian M. Smith and D. V. Griffiths are downloadable from: www.mines.edu/~vgriffit/4th_ed/Software This title demonstrates how to develop computer programmes which solve specific engineering problems using the finite element method. It enables students, scientists and engineers to assemble their own computer programmes to produce numerical results to solve these problems.

Please allow me to note that I have recently published in Philosophical Magazine a paper that presents a general approach to Gibbsian surface thermodynamics that includes a treatment of solid surfaces.  It can be accessed through the following link: 

http://www.informaworld.com/smpp/content~db=all~content=a792987191

Recently published, this special issue of the Journal of the Mechanical Behavior of Biomedical Materials, dedicated to ‘Nanoindentation of Biological Materials' provides a snapshot of the novel uses on nanoindentation technology that is now readily available to researchers and expands the scope of existing techniques to optimize methods for biological tissues and related biomaterials.
Access the issue online:
http://www.sciencedirect.com/science/journal/17516161 (ScienceDirect subscribers)

June 18 Columbus, OH
Guest Speaker: Dan Turk,Honda R&D Americas\http://www.simulia.com/events/hpc/columbus_hpc_6-18.html

Hi all.

I am modeling a problem of a Double Cantilever Beam in Ansys 11.0,

using Exponential and Bi-linear Cohesive Laws.

For the Bi-Linear law, Ansys needs to introduce 6 constants, like the Critical Fracture Energy Gc, the normal stress σ...

The fifth constant, η, is the artificial damping coefficient, introduced to improve the convergence to solution.

Can you help me to understand the nature of this parameter?

Which values of this damping coefficient must be considered for a good modeling of the problem?

Two new papers grabbed my attention on my long unread list of journal tables of contents in Google Reader. 

1) The first was

Ideomechanics of transitory and dissipative systems associated with length, velocity, mass and energy by G.C. Sih

where it is stated that

" One of the rules of the development of IDM is that the “flow of nature” takes precedent when deducting and/or constructing quantitative results. It is hoped that

PNAS 106, 10103 (2009), doi:10.1073/pnas.0905193106, http://www.youtube.com/watch?v=dPJBalMZ824&feature=channel_page,    http://www.nanowerk.com/news/newsid=11108.php

A one-year post-doc is available in conjunction with

1) Prof. Asenov, University of Glasgow

2) Dr. Bordas, University of Glasgow/Cardiff

 to study the behaviour of nano-CMOS semi-conductors.

Please write to stephane dot bordas at g ma i l dot com 

 for details with your:

1) CV

2) Three references

3) a statement of why you are qualified and interested in this position

 You should

1) have a strong background in finite element methods

2) excellent programming skills in MATLAB and C++

This position starts in July 2009 and lasts for 8 months. 

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http://www.sciencenet.cn/blog/user_content.aspx?id=237550

Journal of Mechanics and MEMS   (JMM)

ISSN : 0974-8407

纪念叶开沅教授专刊(英文)

ECCMR 2009 - Sixth European Conference on Constitutive Models for Rubber

Held at TU Dresden, Germany, September 7-10, 2009. 

www.eccmr.org