iMechanica - biomechanics - Comments

Smoothness of crack tip fields in X-FEM and error estimation

Stephane Bordas — Wed, 29 Oct 2008 06:44:15 -0400

Dear Pooyan,

What you are describing is not a problem with your code (at least not necessarily).

There are many papers on this topic, for instance, I recommend the following:

http://doi.wiley.com/10.1002/nme.1601 by Karihaloo Improving the accuracy of XFEM crack tip fields using higher order quadrature and statically …

Direct evaluation of accurate coefficients of the linear elastic crack tip asymptotic field by Karihaloo again

XFEM for direct evaluation of mixed mode SIFs in homogeneous and bi-materials still by Karihaloo

Derivative recovery and a posteriori error estimate for extended finite elements by Marc Duflot and Stephane Bordas

http://www3.interscience.wiley.com/journal/119054430/abstract by Marc Duflot and Stephane Bordas

A recovery-type error estimator for the extended finite element method based on singular+smooth … by Rodenas, etc.

A Global Explicit Residual Based Error Estimator for the eXtended Finite Element Method in … by Geniaut and Delmas

A simple error estimator for extended finite elements (Marc Duflot and Stephane Bordas and Phong Le)

Numerical Aspects of the extended Finite Element Method by Peters and Hackl

Do let me know if you would like preprints of those articles, which I could provide.Our XFEM matlab code could be of interest to check your code as well. I wonder if you could describe what you mean by extrapolation technique specifically?

Many thanks,

Dr Stephane Bordas

http://people.civil.gla.ac.uk/~bordas

X-FEM tip enrichments

pooyan broumand — Tue, 28 Oct 2008 10:33:26 -0400

Hi ;

I am modeling quasi-static crack propagation with x-fem .

for calculation of SIFs I used the extrapolation method , but I found that the displacements at the tips are not very smooth and are turbulated. and as the result the SIF calculated are not correct .

Why the displacements are not smooth, and there exist a high gradient in the tip element. is it in X-Fem nature or it is my code problem?!

another thing is that where should the points to be used in SIF calculation be located ?

In FEM they are located at the edges of the crack but in X-FEM there are turbulances near the crack edge and this will affect the results.

thanks

Doubts on nanoindentation computational modelling

aravind_eight — Mon, 13 Oct 2008 16:44:34 -0400

With regards
Aravind

Q.Y.Casjeon

casjeon — Mon, 16 Jun 2008 20:59:43 -0400

Q.Y.Casjeon

Fangsen, Thanks for your

Teng Li — Thu, 24 Apr 2008 11:17:21 -0400

Fangsen,

Thanks for your kind words. In the above paper, the buckling of microtubules is studied in an analytical manner. As discussed in the paper, the model captures certain key features of the MT buckling, but is far from comprehensive to shed insights on some other interesting and important features. Simulations via FEM and/or MD will be needed to reveal the underlying mechanisms of such features. We are working along this line.

-Teng

Very interesting work! Is

Fangsen Cui — Sun, 20 Apr 2008 22:24:09 -0400

Very interesting work!

Is it possible to use commercial software such as ABAQUS to simulate the buckling of the microtubules?

Re

Konstantin Volokh — Wed, 12 Mar 2008 12:55:06 -0400

Dear Teng,

Thanks for your kind remarks!

The topic itself is of great practical importance because surgeons do not have reliable and rational criteria for predicting the aneurysm development and possible rupture. There exist only empirical criteria based on the previous experience...

Hopefully, the visitors of iMechanica will be able to contribute to the subject!

Re: Mechanics of growth and rupture of abdominal aortic aneurysm

Teng Li — Wed, 12 Mar 2008 12:34:50 -0400

Kosta,

Very neat model! I quickly went through your paper and found it interesting.

Zhigang talked about the inflation of a balloon (or bursting of an aneurysm) in his Solid Mechanics course. I also gave the students a similiar example when I taught Continuum Mechanics. It's nice to see the latest progress on this topic. Thank you for sharing your publication.

Interesting work!

Yanfei Gao — Fri, 07 Mar 2008 10:30:56 -0500

Interesting work!

Re: on-line visualized experiments

Teng Li — Tue, 26 Feb 2008 10:47:58 -0500

Tian Zhi,

Thanks for your post.

In an earlier discussion, jove.com was mentioned. You may find the discussion there interesting.

Sınıf

asykro — Wed, 13 Feb 2008 16:49:19 -0500

Sınıf dizisi

book on Helical Wormlike Chains and free online book

Andrew Norris — Fri, 08 Feb 2008 09:57:50 -0500

Helical Wormlike Chains in Polymer Solutions, by Yamakawa, Hiromi, Springer 1997

This book is technical but very informative. It goes into the details of the WLC model more than any other book that I know of.

Most libraries don't have t hat book - but a good alternative is the older 1971 text "Modern Theory of Polymer Solutions" by Yamakawa which contains a good deal of the same material and is more introductory. And the 1971 book is available for FREE in pdf form here .

Thank you vey much for your

BirosTheo — Thu, 07 Feb 2008 15:21:49 -0500

Thank you vey much for your infos

In the Cowin and Doty's

Almir Uzunovic — Thu, 07 Feb 2008 13:19:02 -0500

In the Cowin and Doty's book "Tissue Mechanics" there is a section related to modelling of spiral structures and issues such as chirality and singularity. While problem is explained from the continuum mechanics' point of view (primarily related to modeling of materials such as wood and horn), the authors provide enough references for further study. The book has it's web site on http://tissue-mechanics.com/

I hope this helps.

Almir

Graduate student position at Royal Institute of Technology (KTH)

Fred Nilsson — Fri, 11 Jan 2008 11:19:35 -0500

See http://www.hallf.kth.se/NYAJOBB/nyajobb_en.html

The position is at the Department of Solid Mechanics, KTH . The theme of the graduate student project is "Crack growth in rubber and rubber like materials".