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Can microscopic coefficients always be derived from macroscopic coefficient (biot effective coefficient, skempton coefficient)?

Submitted by Xiaogai Li on
Can microscopic coefficients always be derived from macroscopic coefficient?

To be more specific, 
alpha: Biot-Willis coefficient, Skempton coefficient 

These two parameters are derived from the macroscopic level which reflects the response of a porous material as a whole, without explicitly taking into account the individual contribution of its solid and fluid constituents.

beginner of MD/DD. what are all the topics that need to be covered?

Submitted by krnk on
education

Dear iMechanica memebers,

I am a PhD student. I started to work on MD and DD. I know the overview of the  MD and DD,but to have the good basics (statistical mechanics, quantum mechanics, classical mechanics and dislocation dynamics ) knowledge,  i am not getting where to start and where to end these subjects.

could any one tell which are the main topics to be covered in the above subjects, if possible could any one suggest good books related to these subjects. 

could any one please help me in this regard.

 with best regards

Create geological fault using Abaqus CAE

Submitted by Joyce on

Hi I am new to modeling. I am currently using Abaqus to do a model on basin inversion. However, I have never done modeling or any similar thing, I don't quite know how to produce a final model with an initial model that has no fault, just nothing.

If anyone can please help me on this, I would like to start with simple models which is a model with graben horst and a model with thrust fans. These models are to be in their cross section (not 3D models). Detailed information is much appreciated.

Joyce

Analytical buckled mode shapes of ring

Submitted by anishiitk on

Hi,

I am facing problem in finding the analytical exact buckling mode shapes
for ring. I have already found buckled shapes through ABAQUS, and now I
am trying to find the buckled shape through some analytical equation.
If anybody has some idea about it, so please let me know. Can it posible
to get the exact analytical equation for buckled shape of ring which
approximate match with ABAQUS result.

Anish Kumar

M.Tech. (Solid Mechanics and Design)

Mechanical engineering department

IIT Kanpur, India.

Book request...

Submitted by George Papazaf… on

Dear all,

I am searching for the following book:

"Some basic problems of the mathematical theory of elasticity" by Nikolai Ivanovich Muskhelishvili.

If somebody has a softcopy I would appreciate it if he sent it to me. If someone has a hardcopy and can lend it to me for a few days, I would be grateful...

Thanks in advance,

George Papazafeiropoulos

Analytical buckled mode shapes of ring

Submitted by anishiitk on

Hi,

I am facing problem in finding the analytical exact buckling mode shapes for ring. I have already found buckled shapes through ABAQUS, and now I am trying to find the buckled shape through some analytical equation. If anybody has some idea about it, so please let me know. Can it posible to get the exact analytical equation for buckled shape of ring which approximate match with ABAQUS result.

Anish Kumar

M.Tech. (Solid Mechanics and Design)

Mechanical engineering department

IIT Kanpur, India.

Effect of External Normal and Parallel Electric Fields on 180^o Ferroelectric Domain Walls in PbTiO3

Submitted by arash_yavari on

We impose uniform electric fields both parallel and normal to 180^o ferroelectric domain walls in PbTiO3 and obtain the equilibrium structures using the method of anharmonic lattice statics. In addition to Ti-centered and Pb-centered perfect domain walls, we also consider Ti-centered domain walls with oxygen vacancies. We observe that electric field can increase the thickness of the domain wall considerably. We also observe that increasing the magnitude of electric field we reach a critical electric field E^c; for E > E^c there is no local equilibrium configuration.

mechanics problem Dahl and Crandall

Submitted by kapornith on
education
displacement values

Hi All,

I am doing a problem on mechanics and find that the answers are not matching (mine are coming .0085 and .002 inch).I am attaching the question and the answer herewith.

I presume that bending effect is not to be taken into consideration as otherwise the dimensions of the beam would have been furnished.I tried both direct stiffness and virtual work methods and didn't get the required answer.

Can anybody validate the same.I restrain myself using FEA analysis fo it as it would have taken thet bending effect also.

Thanks and Best Regards

Help!!VUMAT Abaqus 6.10-1 ERROR LINK

Submitted by checcovschecco on
Hi there,
I'm a new member of imechanica; I'm using Abaqus 6.10-1/Explicit to analyze the impact of a rigid ball onto a composite plate. I installed fortran compiler ifort 11.1. I'm using VUMAT subroutine (material model is based on Hashin's failure criteria).
This is my Abaqus_v6.env file:
compile_fortran=['ifort', '/c' , '/Gm', '/recursive', '/nologo', '/heap-arrays:1', '/include:%I']
link_sl='cmd /c "LINK /nologo /INCREMENTAL:NO /subsystem:console /machine:X86 /NODEFAULTLIB:LIBC.LIB /NODEFAULTLIB:LIBCMT.LIB /DEFAULTLIB:OLDNAMES.LIB

Research Fellow/Research Assistant positions for mechanism design/vibration analysis of actuators for 10 Tbits/square HD Drives

Submitted by mpeleehp on
job

Our group has two research openings for people with expertise on mechanism design / dynamic and vibration analysis of actuators cater to 10 Tbits/square inch hard disk drives. Please send your cv to me at mpeleehp [at] nus.edu.sg (mpeleehp[at]nus[dot]edu[dot]sg) or Prof Ong CJ at mpeongcj [at] nus.edu.sg (mpeongcj[at]nus[dot]edu[dot]sg).

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