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I am trying to learn non linear FEA ( Newton Raphson method)and this is what my understanding is. Kindly advise if you think my understanding is correct.

1) At the beginning of the analysis, I am using a small load step and using the current stiffess matrix ( which I am designating as initial tangent stiffness) I am solving for the initial displacement step for this load.

Here my question is: How this initial  tangent stiffness is calculated?

 The way I look at it:

Chwee Teck Lim's picture

50 Post-Doctoral Positions available at the new Research Center of Excellence in Mechanobiology

 

A new $150M Research Center of Excellence (RCE) on Mechanobiology has been set up at the National University of Singapore  (http://newshub.nus.edu.sg/headlines/0209/TRCE_20Feb09.php).  We are now in the process of hiring 50 good post-docs. 

Post Doctoral Position in Multiscale Modeling of Radiation Induced Damage

There is an opening for a postdoctoral research position in the Advanced Computational Research Laboratory at RPI, Troy NY to work on a multiscale modeling project which involves the modeling of radiation induced damage of metallic materials. Encouraged to apply are creative, self-motivated candidates with a sound background in computational mechanics. Qualifications: 1. PhD in Computational/Applied Mechanics / Materials Science or related topic. 2. Sound background in nonlinear solid mechanics. 3. Sound background in FEM technology. Prior experience in multiscale modeling is a plus. 4.

Postdoctoral position in Multiscale Modeling of Composites

There is an opening for a postdoctoral research position in the Advanced Computational Research Laboratory at RPI, Troy NY to work on a project sponsored by the Army Research Office involving multiscale modeling of 3D woven fiber composites under high strain rate loading conditions. Encouraged to apply are creative, self-motivated candidates with a sound background in computational mechanics. Qualifications: 1. PhD in Computational/Applied Mechanics or related topic. 2. Sound background in nonlinear solid mechanics. 3. Sound background in FEM technology.

Position at Ecole Polytechnique, France

APPLICATIONS ARE INVITED

for a top-level scientific leader, who will become head of

the Laboratory of Solids Mechanics, CNRS , Ecole Polytechnique,
Palaiseau.

see attached file (in English) or go to:  http://www.enseignement.polytechnique.fr/mecanique/Postes/appel-LMS_09.pdf

Faculty Positions at the University of North Texas

The Department of Mechanical and Energy Engineering invites applications for a tenure-track faculty member at the rank of assistant professor, associate professor, or full professor preferably in the areas of controls, solid mechanics/design.  Applications will be reviewed until the search is filled. For complete qualifications and applications information see http://www.mee.unt.edu. AA/EOE/ADA

Mogadalai Gururajan's picture

Growth kinetics of precipitates: misfitting and non-misfitting

Quantitative studies on diffusional growth of an isolated
precipitate in a supersaturated matrix date back to the classic work of
C Zener (1949) and F C Frank
(1950); while Zener-Frank (ZF) theory is for precipitates that are
non-misfitting, misfitting precipitates have been studied by Laraia,
Johnson and Voorhees (1988) (hereafter, LJV). Both ZF and LJV are sharp
interface models (and are mostly analytical); further, the assumptions
made in these theories make it difficult to verify their results by

LECAM's picture

Experimental temperature field at the crack tip in a natural rubber

Dear colleagues, this is a paper on the experimental determination of temperature field at the crack tip in a natural rubber using a motion compensation technique. The contribution of the non-uniformity of the IR detectors and the Narcissus effect is taking into account to determine the temperature field.

JB LE CAM

ASME Winter Meeting abstract deadline today

This year’s meeting will take place on 13-19 November 2009, in Lake Buena, Florida.  The deadline to submit abstracts is today (2 March 2009).

Can you become a mechanic by reading books?

Well I am really wondering about thsi right now as I read  that I should really try to further my education via Distance learning .

LECAM's picture

Cyclic volume changes in rubber

This is a study dealing with the volume variation in filled crystallizable natural (F-NR) and uncrystallizable styrene butadiene (F-SBR) rubbers subjected to cyclic loadings. During their deformation, such materials exhibit volume variation induced by the cavitation phenomenon and the decohesion between particles and the rubber matrix.

LECAM's picture

Volume variation in filled and unfilled natural rubber : competition between cavitation and stress-induced crystallization

this is a study on the competition between cavitation and stress-induced crystallization during the deformation of cis-1,4 polyisoprene rubber. During deformation, this kind of material exhibits volume variation induced by both phenomena. In this study, we propose to measure this volume variation by an original full-field measurement technique. The high resolution of this technique allows us to identify characteristic stretch ratios during mechanical cycles.

advice to understand the Gurson Model

Recently, I am studying on the Gurson Model, but it is a little bit hard for me to understand most part in the paper 'Continuum Theory of Ductile Rupture by Void Nucleation and Growth', I don't know about the spirit of deduction of formulas and some keywords make me confused, like 'convexity'and 'normality','loci',many....

It may be helpful if someone who is highly understand better about Gurson can introduce me some references maybe basic or middle hard, Thanks! 

fatigue

Is it possible to find out the number of cycles to failure for a composite material(glass-epoxy) in ansys,with the data known only for material properties,layup,fibre orientaion?The beam (i.e.solid 191 taken for analysis of composite) is to be considered to be given a displacment at one end.

KINDLY HELP ME OUT BY GIVING THE DETAILED PROCEDURE

Shaoxing Qu's picture

Distinguished Professor Position, Zhejiang University

The School of Aeronautics and Astronautics of Zhejiang University invites applications for a full-time distinguished professor position in the field of solid mechanics.  The successful candidate should obtain an earned phd degree from world famous university, must have an excellent academic record, and currently takes full professor or comparative position in overseas world famous university or institute.

Multiscale Science Based-Modeling and Simulation and Experimental Validation on Enabling Materials, - Deadline March 1

On behalf of the NSF Summer Institute on Nanomechanics, Nanomaterials, andMicro/Nanomanufacturing, I am writing to remind you that the deadline for application for fellowships is March 1, 2009, for the short course entitled "Multiscale Science Based-Modeling and Simulation and Experimental Validation on Enabling Materials", to be offered from May 27 to May 30, 2009 in Evanston, Illinois.  The short course will first cover science-based modeling and simulation methods for general classes of enabling materials.

Michael Borowicz's picture

Hard stage materials in Ansys

Hello,

I'm trying to simulate and compare principal stresses in model of bolt and nut, for different material data. I would like to get the soft/hard stage comparison. The problem is that I just do not know how to define hard stage material, it is not in standard material library in ansys (workbench or classic).

If anyone could help me giving some examples of hard stage materials data I would be greatfull.

Shaoxing Qu's picture

In Chinese: 浙江大学航空航天学院面向国内外公开招聘启事

浙江大学航空航天学院面向国内外公开招聘启事  浙江大学航空航天学院于2007121

azadpoor's picture

Failure of protein materials in disease and other extreme conditions

The recent issue of Nature Materials includes a review paper on the deformation and failure of protein materials in physiologically extreme conditions and disease. The paper was interesting, so I am posting the abstract here. For the full-paper visit Nature Materials.

Nature Materials 8, 175 - 188 (2009) | doi:10.1038/nmat2387

Deformation and failure of protein materials in physiologically extreme conditions and disease

Markus J. Buehler & Yu Ching Yung

UMAT: Calling a another subroutine in UMAT, Errors during job execution

Hi,

I am in process of implementing the Bergstroem-Boyce Model. In a first
step I am just considering the hyperlastic part of it (Network A:
8-chain). I have implemented this part in a UMAT using a numerical
approach for the elasticity tensor (Forward Difference Approximation
with perturbation of F).

I have two problems:

1.
------------------------
In order to keep my UMAT as easy to read as possible I have tried to keep the FDA in a separate file using

call KFDA_Jaumann(dfgrd1,......)

azadpoor's picture

A recent paper about friction laws at the nanoscale

A very recent paper published a few minutes ago in Nature addresses the issue of friction laws at the nanoscale. Here is the abstract of the paper.Interested? here you can download the paper.

Nature 457, 1116-1119 (26 February 2009) | doi:10.1038/nature07748; Received 3 September 2008; Accepted 23 December 2008

Friction laws at the nanoscale

Yifei Mo1, Kevin T. Turner1,2,3 & Izabela Szlufarska1,3

L. Roy Xu's picture

ASME Congress 09 on the Mechanical Behavior of Nanocomposite Materials

You are invited to present your research work on the mechanical behavior of nanocomposite materials (Nov. 13-19, 2009 in Florida, close to Disney World). This topic will be focused on systematic mechanics experiments, modeling and simulations to solve new challenging mechanics problems such the effect of nanofiller agglomeration on the stiffness and strength reduction; interfacial stress transferring and interface strength evaluation at the nanoscale.  Deadline for abstract submission is March 17, 2009.

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