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Arash_Yavari's picture

On the geometric character of stress in continuum mechanics

This paper shows that the stress field in the classical theory of continuum mechanics
may be taken to be a covector-valued differential two-form. The balance laws and other funda-
mental laws of continuum mechanics may be neatly rewritten in terms of this geometric stress. A

zishun liu's picture

Computational Cancer Mechanics

Since Dec. 2006, Institute of High Performance Computing (IHPC) has set up a biophysics research team that comprises research scientists in the fields of biophysics, solid mechanics and fluid mechanics, and has kicked off the "Computational Cancer Mechanics" project.

Tianlei Li's picture

Does anyone know where I can find the stress field of a perforated strip?

I am trying to get the shrinkage rate of a void in a finite grain which is simplified as a rectangular region within a circular hole. So I need to find out the stress field to get the chemical potentials.

rajnikanthreddy's picture

EFG with Lagrange Multipliers for elastodynamic problems

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hi ,

by using EFG with Lagrange multipliers for elastodynamics we will get below two equations .

M (U double dot)+C (U dot) + KU = F   (ofcourse C=0 in my problem)

HU=q    (q is not equal to zero) (where  H= G Transpose)

Henry Tan's picture

Granular mechanics

Granular materials deserve being investigated as this has been the case with liquids, gases and elastic materials.

Titanium and nickel Functionally graded materials

Hi,

i would be working of development of titanium and nickel functionally graded materials by laser deposition. I would appreciate any suggestions and know-how about this specific topic.

Kamran.

B.Banerjee's picture

What are the basic difficulties of using the collocation techniques for solving PDE’s?

Hello, Can anybody inform me what are the basic difficulties of using point collocation (strong form) kind of method for solving pde's when compared with solving its weak statement? I have listed a few, known to me,

Floating ships of ice and increasing the toughness of glass

http://en.wikipedia.org/wiki/Project_Habakkuk

I was surprised several years ago when delving into the literature to not find any references about addition of nanoparticles to ice, to study their impact on the mechanics of ice.  In short, to make nanocomposites where the matrix is ice.  So, with 2 high school students from IMSA, the Illinois Math and Science Academy, we set about (with their limited time for a bit of research) to try adding some nanoparticles to water and to freeze it.  The students simply used their home freezers to do this, and their mechanics measurements were with a hammer and chisel...

Non Destructive Evaluation of a Ceramic Matrix Composite

Background of Study

  • Non destructive evaluation (NDE) application
  • Based on industrial CT scan
  • Visualisation and segmentation of internal anomalies

FE mesh of particulate-reinforced metal matrix composite

Background of Study

  • Based on X-ray tomography (XMT)
  • Multi-part FEA model
  • Scan to mesh in 10 minutes

Aluminum-based particulate-reinforced metal matrix composites (PMMCs) frequently have a heterogeneous distribution of reinforcement particles whether produced by a powder or liquid processing route. The applicability of X-ray microtomography (XMT) for the characterization of this heterogeneity and its influence on final properties was investigated, for the case of a powder blended and extruded AA2124 matrix with Ni particulate. Simpleware software was used to quantify the embedded Ni particle size distribution and the extent and texture of clusters formed.

Analysis of a golf ball hitting the eye

Purpose of the Study
Computer models of the human eye were constructed for the purposes of studying interactions with foreign bodies.

  • Based on in vivo patient data
  • Multi-part model
  • Mixed volumetric and surface meshes
  • Automated generation of contact surfaces

Scan and Segmentation in ScanIP
High resolution in vivo MRI scans of a 29 year old Caucasian female was obtained using both a surface and a head coil on a Philips Gyroscan 1.5 Tesla imager. The following structures were segmented from the 3D data set by a Physician: the globe and optic nerve, the bony orbit, the eyelids and facial soft tissues, the extra-ocular muscles.

Mesh Generation in +ScanFE
A number of finite element models were generated based on the segmented image data. Each structure was meshed with mixed hexahedral and tetrahedral elements. The contact surfaces are particularly robust as the master and slave contact faces are paired - contact structures were exported as volumetric meshes and as surface meshes as required. For this application, the bony orbit was modelled as a rigid structure defined by surface shell elements rather than as a volumetric mesh thereby providing some computational saving.

FE Analysis in LS-DYNA
An analysis of a golf ball hitting the eye was carried out to demonstrate the robustness of the model for simulation purposes, as well as to demonstrate the remarkable sophistication of biological models which can now be generated based on in vivo data. This case study was developed in collaboration with Naomi Green at ARUP, Solihull, UK.

jfmolinari's picture

A new methodology for ranking scientific institutions

 

We extend the pioneering work of J.E. Hirsch, the inventor of the h-index, by proposing a simple and seemingly robust approach for comparing the scientific productivity and visibility of institutions. Our main findings are that i) while the h-index is a sensible criterion for comparing scientists within a given field, it does not directly extend to rank institutions of disparate sizes and journals, ii) however, the h-index, which always increases with paper population, has an universal growth rate for large numbers of papers; iii) thus the h-index of a large population of papers can be decomposed into the product of an impact index and a factor depending on the population size, iv) as a complement to the h-index, this new impact index provides an interesting way to compare the scientific production of institutions (universities, laboratories or journals).

Tetrahedral: The key to life on Earth?

It seems to me that tetrahedral bonding is responsible for life on earth. 

One might leap to the (reasonable) conclusion that I am referring to the element carbon and its ability to form sp3 bonds.  Life does depend on carbon, no doubt. But where does life exist, by and large?

Rui Huang's picture

Thin films: wrinkling vs buckle-delamination

H. Mei, J.Y. Chung, H.-H. Yu, C.M. Stafford, and R. Huang, Buckling modes of elastic thin films on elastic substrates. Applied Physics Letters 90, 151902 (2007).

Two modes of thin film buckling are commonly observed, one with interface delamination (e.g., telephone cord blisters) and the other with no delamination (i.e., wrinkling). Which one would occur for your film?

Roozbeh Sanaei's picture

what's the status of Discrete-to-continuum scale bridging.

what's the status of Discrete-to-continuum scale bridging. and it's real application?

Bin Liu's picture

Woven Nano-Structure of Carbon Nanotubes

We have studied the above woven nano-structure of carbon nanotubes as one of potential designs for ballistic-resistance materials via the atomic-scale finite element method (AFEM). Our study shows that this structure is insensitive to structure defects. More details can be found in our paper.

Henry Tan's picture

metal foam

cellular metal: space is divided into distinct cells. The boundaries of these cells are made of solid metal, the interior are voids. Ideally, the individual cells are all separated from each other by metal but often this restriction is relaxed

A new type of bubble raft--challenge for clever students

17 years ago, while a postdoc at IBM meant to be doing other things, I thought about the following. Then recently I visited Ali Argon at MIT, and we discussed conventional bubble rafts and how useful they had been in studies of some problems in mechanics...such as of defects and so on.

Henry Tan's picture

Plastic bonded energetic materials

plastic bonded explosives are composites containing energetic grains, ranging in size from less than one to a few hundred micrometers, embedded in a matrix of high-polymer binder.

Mike Ciavarella's picture

Does anyone know a collection of Lennard Jones potential material constants??

I am trying to find out the theoretical adhesive strength limit of a few materials, or more precisely the ratio adhesive strength limit to elastic modulus. I think this is after all part of the Lennard-Jones constants potential - theoretical adhesive strength limit is simply the maximum of the curve.

Markus J. Buehler's picture

Large-scale hierarchical molecular modeling of nanostructured biological materials

There have been several posts recently discussing new directions in computational mechanics. Here is a review article that appeared recently that may be of interest.

Large-scale hierarchical molecular modeling of nanostructured biological materials

MichelleLOyen's picture

Poroelasticity references

Given the growing interest in poroelasticity within this forum, I thought I would post the link to "Poronet" -- the poromechanics internet resources network.  In particular, there is a nice long pdf chapter on the fundamentals of poroelasticity from Detournay and Cheng, 1993, which has become one of the standard references in the field. 

Research directions in computational mechanics

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Dear all,

I just joined this group last week. And, I'd like to share some of reading material that I found regarding research directions in computational mechanics. The paper was published in 2003, written by Tinsley Oden, Belytschko, Babuska and Hughes. It's entitled "Research Directions in Computational Mechanics" (Computer Methods in Applied Mechanics and Engineering, 192, pp 913-922, 2003). They outlined six areas with significant research opportunities in CM:

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