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Elementary Mechanics and Basic Engineering Thermodynamics

I suppose it is acceptable to announce the work I have online to assist students in learning mechanics and thermo.  The site is  Please take a look if you are interested.

boundary value problems

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Hi All, thanks in advance for any replies.

I am currently doing my Thesis on fast stress analysis using the boundary element method and specifically, adaptive cross approximation. I ofter come across the terms "single layer potential" and "double layer potential", i "know" what they are mathematically, i was wondering if anyone could give me an insight into what they mean physically, or just give a simple non mathematical definition? Thanks a lot, Ian.

GOPALAERO2000's picture

Buckling of Stepped column

Hi everyone,

Does anyone have the work experience on stepped column kind of structure?

I would like to know, how to determine the crippling load for stepped column kind of structures? If anyone have the materials pertaining to the subject, please do share (if interested).


Thanks and Regards


M Gopalakrishnan.

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.

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,

Recommendation for a good entry level text book

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Hi all

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

chenna's picture

Help Regarding PhD opportunities

Hi Suo and other guys,

I am Chennakesava. I am new to this site. I have completed my Masters in Mechanical Engineering from Indian Institute of Technology, Kanpur, India. (IITK) . Year of study is 2006-08. My specialization is Solid Mechanics & Design. Right now am working in GE, India. I want to pursue doctoral degree in the field of Dynamics and Vibrations and related issues like, Rotor dynamics, Smart structures, MEMS, Nonlinear dynamics and Chaos. Its kind of a dream to me. 


Query on transformation representing deformation fo space , change of basis and orthogonal nature

Hello All
I am trying to read the text book Tensor analysis by IS Sokolnikoff and stuck in
chaper 1, there is some confusion in my mind regarding orthogonal transformations,
change of basis and and a transformation representing deformation of space.
Please bear with me if my confusions are unfounded.
1) Is is safe to say that transformation representing deformation of space acts on
vectors where as transformations representing the change of basis acts on
components?. (if yes then the following questions are resolved and need not be
2) Sokolnikoff builds up the reasoning for orthogonal transformations based on
deformation of space (i.e orthogonal transofrmations keep the length of vector

jintting's picture

Strain Energy Derivation

Dear Sirs,

I'm trying to derive an strain energy in a small volume 2a x 2b x 2t.

I can derive "The rest terms are ommited" by myself . 

By the way, I can't derive the DT2 term in the 2nd row of the figure.

Please help with reference or tips.


Jin Kim

Taxonomy upgrade extras: 

Modeling bone and implant

I'm working with multiple meshed items and attempting to cut them using the Instance boolean operation. My parts include parts I've sketched & meshed in Abaqus and a 3D object I imported from MIMICS (.inp file). When I attempt to selectively cut the instances that overlap, Abaqus failed. Any suggestions on the modeling of bone and implant with a reasonable fit in geometry?

Composites modeling

Hi i want to model a compsoite shaft of glass/epoxy .i am having all material properties .i want to know how to model it .and in another case there is adhesives between the two.



Mehdi Naderi's picture

Cyclic Plastic Dissipation Calcualtion in UMAT

During Fatigue temperaure of materials increases due to plastic deformation.  I am trying to calcualte plastic dissipation in UMAT and use it as heat source in HETVAl to get temperature rise.  I do not know how to add plastic dissipation calculation in UMAt.  I am wondering if some body  give me an example which is done close to what I want to do.

suggestion on a project.............

   hii every one ... i am an  undergraduate student in mechanical enggineering . can any 1 suggest me a good project which includes  1.both computer oriented and also lab oriented project.

2.  also a  project in fatigue analysis.

Murat's picture

Different Stress Values between brick, beam and hand calculation?

Hello Everyone,

I have run a simple beam simulation of a cantilever pipe. I calcualted it with 8-Node brick elements, beam elements and hand calculation. At the up and low edge of the beam connection to the wall, I got maximum stress values as expected. While the beam and hand calculation results are similar  (40 MPa), brick element calculation is higher. (50Mpa). Interestingly the finer the mesh of brick elements the higher the stress values. I couldnt figure out the reason of it. Can any one say a comment?

 Thanks in advance


hookes law

why the stifffness matrix is foutrh order ?

cyclic load

thanks a lot

Iam beginner in ansys, so i have problem in enter the steps of cyclic load to a plate as solved in ansys to get the deformation with time curve.

can any help me??

nastran .op2 reader

Hi everyone,

I am working on a personal Fatigue Analysis code that read nodes and stresses from FE processors. I would like to read the NASTRAN .op2 output  file. Does anyone know about the structure of this kind of file?




concrete model does not converge

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I am working on a simple concrete model. The model fails
to converge for relatively smaller loads. I am not very proficient with
abaqus. If someone can tell me what to tweak to get it running, I'll be

Please take a look at the inp file attached.

FEA of Crack Propagation

Hi all,I'm a student of of Madras Institute of Technology, Chennai.I'm trying to do stress intensity based crack propagation in metals. I’m using Abaqus/CAE. I’m following the abaqus 6.5 documentation, I have completed upto Contour integral evaluation,” (Section 7.10.2).

Partial Differential Equations for Scientists and Engineers


I am an instructor who teaches the partial differential equatioin for mechanical engineering students at Myong Ji University in South Korea using the book, "partial differential equations for scientists and engineers" written by Prof. Stanley J. Farlow.

Luckly our department professor handed me over a copy of solution manual but which was not completed. Thus I wonder if anyone has a complete solution manual for this book. It will be grateful if I may be able to obtain a complete solution manual.

Thank you very much,

Young June Yoon

Mixed formulation

Dear All


 Does anybody have this paper?.


On some variational principles in the theory of elasticity and the theory of plasticity

HC Hu - Scientia Sinica, 1955

Thank you


Teng Li's picture

Your Students Are Your Legacy

by Prof. David A. Patterson (Professor of Computer Science at U.C. Berkeley,Fellow and past president of ACM)

Viewpoint from a Berkeley professor after 32 years of mentoring Ph.D. students. Hope you enjoy as I do.

You may also find an earlier discussion thread in iMechanica interesting:

Learning to be a PhD advisor




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