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Help with wind tunnel experiments

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In our wind tunnel experiments, we have wake survey of a cylinder and boundary layer measurement for a thin flat plate as two experiments. We measure the stagnation pressure(Pt) at points using a pitot tube. We also measure the static pressure of the free stream Pinf.

Cell sensitivity to substrate stiffness

Cell sensitivity to substrate stiffness

Submitted by Daniel Isabey on Wed, 2009-04-15 15:03.

In Féréol et al. (Biophys. J., 2009, 96: 2009-2022),
we propose a coupled theoretical and experimental study in order to understand the
mechanism of cell sensitivity to substrate stiffness. To do so, we first consider
that adhesion sites pass through different stages of development, e.g., Initial
Adhesion (IA), Focal Complex (FC), Focal Adhesions (FA), characterized by the

Openings Available: Ph.D. students in MEMS/Nanotechnology

The Penn State Biofunctionalized Nano-Electro-Mechanical-Systems (BioNEMS) Laboratory ( is actively recruiting highly motivated, qualified Ph.D. students. 


Amit Pandey's picture

Outstanding Scientists : New Delhi (India)_ CSIR


Oppurtunity for experience scientist and professors at

Council of Scientific & Industrial Research [CSIR]:

You have a mission back home in India

India beckons leaders to push the Frontiers of Science and Technology

Jayadeep U. B.'s picture

Symmetry of Infinitesimal (linear) strain tensor

Hello everyone,

 Why do we have the infinitesimal (linear) strain tensor to be symmetric? The reasons, which I have understood so far are:

1. It is defined to be symmetric so that it behaves like a tensor.

2. The stress tensor, which is its energy conjugate, is symmetric, and hence the skew-symmetric part has no contribution towards strain energy.

 Can anyone suggest more fundamental reason(s) for the symmetry of linear strain tensor, like the moment equlibrium leading to symmetry of the Cauchy stress tensor?

Thanks in advance,

GOPALAERO2000's picture


Hi everyone, 

Sometimes while replying for the answered queries, I face the issue of "COMMENTS FIELD IS REQUIRED" inspite comments field is filled. I have attached the same in the presentation. Please go through it help in this regard.

Thanks and Regards
M Gopalakrishnan


Recommendation for a good entry level text book

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Hi all

Warning messages related to negative eigen values while using Abaqus Standard

Hi all,

 I am working on simulation of necking in a uniaxial tension test using sheet specimens of 1 mm sheet thickness. I have given stress strain data upto a plastic strain of 1 , I am using 4 elements in the thickness direction of the sheet.My job is able to complete but with lot of warning messages as follows:

1) The strain increment has exceeded fifty times the strain to cause first yield at 286 points

2) The system matrix has 174 negative eigenvalues.


I am doing analysis in ANSYS which requires the contact pair to be defined. I am unable to select an appropriate value of Pinball region, Penetration Tolerance and normal penalty stiffness. Does any body have an idea how to select the good values for better solution? If you have anykind of material related to contact pair kindly email me at


Dear Prof.Barber, This is the proof


Dear Prof.Barber,

     This is the proof of the theorem I mentioned before. This proof is recorded in a book

  (titled as variational principle in elasticity and its applications)  written by Prof.Hai Chang Hu, one of the inventors of the well-known Hu-Washizu generalized variational principle. It is written in Chinese. I translated it into English. Of course, all errors and misunderstandings are due to me. I think this proof is elegant and accessible to most of the students with engineering background.

  Hope it helps


GOPALAERO2000's picture

From the Ph.D Student

Hi Every one


 I am a new entrant to this site. This site seems to be very good towards technical aspect.

First of all I would like to introduce myself. I am a Ph.D student working in the area of fatigue.

- Is there anyone to support and share the knowledge in the domain of fatigue?

- Can anyone guide towards the websites that provides very good information about fatigue and related literatures.


Thanks and Regards

Gopalakrishnan Mohanam


Marina Trajkovic's picture


Dear all,

do you know does any entry stored is STATEV, used in UMAT subroutine,
should remain unchanged for the next increment for the case of finite
I know that STRESS and STRAN  will be rotated by ABAQUS but what about the STATEV?

I want to protect STATEV from any rotation by ABAQUS in order to rotate
it in UMAT by my rotation matrix but I am experiencing that it is
different value at the beginning of new increment in comparison the one
as output from previous increment.

Thanks in advance,


2009 Gordon Research Conference on Adhesion

Location:  Colby-Sawyer College, New London, NH, United States
Sunday, July 26, 2009 - Friday, July 31, 2009
Chair:  Jeffrey T Koberstein (Columbia University)
Vice Chair:  Chung-Yuen Hui (Cornell University)
Web Site:

Online Application:

Zhigang Suo's picture

Learning temperature, pressure, and chemical potential

I have updated sections of my notes on thermodynamics.  A few thoughts on learning are collected here.  Of our world the following facts are known:

Hertz contact question

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Dear all

I'm doing an analysis where i need to evaluate the contact area acoording to hertz theory.

I have a book which shows me every step, except for how to calculate two coefficients, and insteads gives me a table of calculated values. 

For the contact patch dimensions a and b, i get the expression

Optimal structural design against elastic instability

In the classical Euler buckling problem, the critical buckling load can be increased by a factor of four if the first mode is suppressed by placing an additional simple support at the mid-point.

If we solve the more general problem where the additional support is placed at some different point z=a in 0<z<L, the critical load will be found to increase above that for the unspported first mode, but the maximum increase is achieved when the support is at the mid-point and buckling then occurs of course in what would have been the second mode of the unsupported beam.

The issue of the computation of the deformation gradient in Abaqus

Hi everybody,

I am trying to model an anisotropic hyperelastic material in plane stress under uniaxial tension

where W=Wiso +Wani= C10*(I1-3)+C4*(I4-1)2 .

 When the load is parallel or perpendicular to the fiber direction, the deformation gradient returned by Abaqus matches the theoretical expression obtained after derivation of W. 

However, when the fiber direction is neither parallel nor perpendicular to the load, the deformation gradient returned by Abaqus differs

modelling of axisymmetric cold extrusion die by abaqus

 my problem is simulation of axisymmetric cold extrusion die. the die is conical, i have to determine die pressure, ram force and temprature in billet as well in die, plz see attached file and see simulation figure, my problem is same as in file,i have facing interaction problem in abaqus while solving this problem. plz help me

Post-doc position

1 year post-doc position : Study of an adhesive bonding aluminum/polymer (October 2009)  


Institut Jean Le Rond d'Alembert (IJLRA) University Pierre and Marie Curie and CNRS - PARIS France



My 1st Paper!

Salam and Hi!

My 1st paper was published in Jurnal Mekanikal UTM in June 2008. Please comment and critic on my research works! The paper is here, PREDICTION OF PROGRESSIVE FAILURE IN WOVEN GLASS/EPOXY COMPOSITE LAMINATED PANELS



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