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CFD Based Aeroelasticity

Can anyone provide some guidelines regarding  CFD based aeroelasticity? And if possible some references as well.  

crack in abaqus

Hello everyone,


When you create the model (for example a rectangle sample) in abaqus, I don't understand how you apply a crack and how you have a stress distribution in all the sample. Can somebody advise me ?

Thanks in advance.


What is "Eigen*****" in ABAQUS?


Can everybody explain me about "eigensolver , eigenfrequency , eigenmode , eigenvalue , ..."?

Thanks in advance


Fatigue Crack Propagation Analysis by means of ANSYS

HI Every Body

 I am postgraduate student of NavalArchitecture, My thesis is Fatigue Crack Propagation in ship Industry, I want to use Ansys Software for this purpose, at first I generated a plate with a central Crack and did fine mesh around crack and saw the results, for next step I should propagate the crack, my questions are as below:

1. How we can predict the Crack path?

2. how should I growth the crack? shall I clear mesh and extend the crack or.....???? I don't know?

3. How Can I use from Interface Elements?

 Thanks in advance

Surface Energies? Continuum Molecular Dynamics?

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I recently encountered the research of Phil Attard and others, in which the contact problem is solved, relaxing the restrictions of the traditional contact models (Hertz, JKR, DMT) and solving based on a formulation where the governing equations are derived using finite-range surface forces and calculated numerically, self-consistently.

Model Overconstraints

Hello all,

I have created a 3-d dynamic model in ABAQUS using shell elements.  When I run the analysis I get several warning messages indicating that I have zero pivot nodes.  When I locate where these nodes are, I find that they are in the middle of my beam (modeled with shell elements) away from any boundary conditions.  Does anyone know why ABAQUS is indicating these inconsistent overconstraints in the middle of my model???  The analysis fails to converge when NLGEOM=yes but has no problems converging when NLGEOM is removed.

Thanks in advance

ABAQUS damaged plasticity model

I am trying, quite unsuccessfully, to model a composite steel frame under dynamic loads.  The problem is nonconvergence brought upon by the concrete tensile strains (i think).  Apparently ABAQUS kills the analysis once cracks form in the concrete.  Has anyone had any success using the "Concrete damaged plasticity model" under cyclic loads and large strains.  I have found that researchers use all types of ghetto concrete properties to get convergence, but I am more interested in a better concrete representation.

Any help on this would be greatly appreciated.

If common block can be used in UMAT for parallel computing

Hello everyone

I wrote some codes with umat recently .  They can work well with single CPU. However, the results become very bad for several CPUs. 

I define a matrix with COMMON BLOCK and it seems that COMMON BLOCK can not be used for parallel computing. Are there any ways to resolve this problem?

I am not familiar with fortran.Someone told me that the matrix should be defined by MODULE. I don't know about this.

Please give some helps to me






Wayne Chen's picture

Faculty Positions in Aeronautics and Astronautics at Purdue University

Two faculty positions at Assistant/Associate Professor lavels are open in the School of Aeronautics and Astronautics at Purdue University, West Lafayette, IN ( The positions are open to all specialties complementary to current AAE research areas.

lagrangian/eulerian views

Hello, a simple question about the Lagrangian and Eulerian descriptions of fluid flow.

When is the Lagrangian (particle point of view) useful? It seems
that the Eulerian is always the right one, since velocity and pressure
are fields.....

thanks !


open issues in interface mechanical modeling

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Hi everyone!

I'm brand new of this website, but I'm already very excited about it - it's really helpful.

using abaqus in sintering

hi, i am currently working on using abaqus software for solving sintering problems . i just want to know how i can introduce new parameters into abaqus so that by giving some eqns for those i can solve the values of final porosity, shrinkage etc that are not pre-determined in the abaqus . i want to know the porosity distribution  and shrinkage rate in a particular given problem as outputs . please help me out . thnq

implementation of nonlinear fem

Hello everybody,

 In the implementation of nonlinear FEM, there are two ways, namely the Voigt notation and the full matrix notation. Obviously, using Voigt notation, one only stores vector instead of matrix. So, by using the symmetry of the Cauchy and second Piola Kirchhoff stress tensors, it is always possible to implement nonlinear FEM using Voigt notation. 

 So, my question is why the full matrix implementation still exists? It is mentioned in the famous book of Ted Belytschko. Only due to historical reason or there are some advantages? 

ANSYS ANIMATION problem: how can I animate the results of a loop (of element death over time)?

I previously posted asking for help with writing command line code to model melting via element death over time.  Biswajit kindly helped me write a loop to kill off any "melted" elements.  Now I would like to animate the results.  I would be very grateful for any suggestions on how to save results from the loop calculations and then animate them.  My aim is to get an animation that shows temperature contours evolving as well as elements disappearing as they achieve a specified temperature.  I am a new user and would find detailed suggestions most helpful.  

vicky.nguyen's picture

Faculty Position Open at The Johns Hopkins University

The Johns Hopkins University, Department of Mechanical Engineering, invites applications for a full-time tenure-track faculty position in the general area of mechanics and materials. Modeling and simulations are of particular interest, but all outstanding candidates will be considered.

Ban.NguyenVan's picture

Ask for contact problem in ABAQUS?

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Hello all,

I'm modeling the railways track system, in which the rail wil be  affixed to the cross tie by Fastening to against the vertical force. 

Now instead of modeling the Fastening, I would like to model the contact between Rail and cross Tie in ABAQUS. I have try surface to surface; surface to node and also tie constrains, but somehow  the results are not reasonable (not agree to experiment result). I thinks the problem is contact properties.

So are there any one can helo me on the problem?

PDF position at the University of New Brunswick, Canada

A post-doctoral position is available in the area of material modeling of composite at the University of New Brunswick, Fredericton, Canada. Particularly, expertise is sought in finite element simulation of damage/fracture and thermomechanical properties of fiber composite. Experience in multiscale finite element modeling of fracture and damage behavior of composite materials is required.

Please contact Dr. Zengtao Chen at the University of New Brunswick for more information. Email:, phone: 1-506-458-7784.

Teng Li's picture

Symposium on Materials and Devices for Flexible and Stretchable Electronics at 2009 MRS Spring Meeting

Call for papers

2009 MRS Spring Meeting, San Francisco, CA, April 13-17

Symposium PP: Materials and Devices for Flexible and Stretchable Electronics

Abstract Deadline: 3 November 2008

Dynamic fracture toughness of PMMA decreases with crack velocity

Dear Alls;

I am loking for the paper which said the Dynamic fracture toughness of PMMA decreases with crack velocity under impact loading, but after crack starts propagation, crack velocity is a decreasing function with crack propagation length.

So, if you know the paper which related to that problem, Could you please show me its title?


Thank you very much,

Best Regards,


Glass thermal stress and fracture

I have an investigation on glass fracture in fire.

I have a fortran program and it can calculate the thermal stress with steady-state temperature and force load using finite element method, Now I want to change it to transient temperature and force load.

I wonder which method should be taken? I'd like to calculate the fracture at last.

Please help me! 

Thank you very much.

you can email to me : or

QS Wang



I am trying to model a tube closed at the two ends by 2 plates.  The cavity enclosed by the two plates and the tube is filled with fluid.  I fix one end and apply a force to the other end.  The tube is a very flixible material and thus all the force should be present as a pressure detected by the fluid.

 When I try to do 2-way-FSI in ANSYS WB with CFX, all the force is taken up by the tube and none by the fluid.  any suggestions?


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