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about the gradient of dislocation core

According to the eigenstrain theory of micromechanics, described in the book by Toshio Mura (micromechanics of defects in solid, 1982) from page 15-20.

He provided the formulas for the eigenstrain at the core of screw and edge dislocation, but I can not understand completely.  

Anybody can provide some reference articles about the gradient value du(i)/dx(j) at the core of screw and edge dislocations respectively?  

 

 

 

 

Damage Model for Steel in Abaqus

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Hi,

I want to try abaqus progressive damage model to simulate steel failure in Abaqus. I read the manual, and found that progressive damage model would be sufficient for my purpose. As I am quite new to damage modeling, I do not know how to determine parameters for shear failure or ductile failure or jjohnson cook model. Also, I would like to use damage evolution as well. Could anyone suggest me some typical parameters for steel (both damage initiation and damage evolution).

Thanks.

Regarding Journals and the Review Process

I thought it might be useful to the iMechanica community to write something about the review process in scientific journals.  For full disclosure, I am one of the co-editors of the Elsevier journal Finite Elements in Analysis and Design.  Indeed, it is precisely that editorship which informs the content of this blog post.  

fracture mechanics

 i want some one to clarify fundamental definition ,inter relationship or difference between the following terminologies .

small strain

large strain

small scale yielding

large scale yielding 

dileepade's picture

HELP IN ANSYS

sir, need help regarding modeling of pyro ejection load where full structure is in airborne..

 

please help ...

dileep

Requesting guidance

I will be very grateful if anybody please guide me about the job opportunities after PhD studies in cellular mechanics in Europe or Asia. My PhD topic is Comptational simulation of mechanical tests with isolated animal cells.

Mike Ciavarella's picture

retirement age or discrimination? Nature speaks of "sticking" around, but in europe we have new laws

In January 2011, the UK government announced its intention to stop
compulsory retirement for people aged 65, despite criticism of the move
by employers’ groups. Campaigners against age discrimination and unions
welcomed the change. However, official guidance makes it clear that
employers will be able to dimiss staff no longer capable of carrying out
their work. Official figures show more than two thirds of British
employers have already eliminated fixed retirement ages.

Lens cement failure

Hello all, I am having problem with one of our lens doublets getting decemented. we have been cementing this lens for many years and we did not do anything different. Recentely we start seeing this lens decementing. we use NO61 and NO65 (UV curing). Any help of how to prevent this problem from happening again will be very much appreciated.

 

Thank you,

 

-BO-

Multiscale simulation

Nowadays, we are talking about multiscale simulation. I am surprising that we discussed about multiscale modeling while units are still exist. In my point of view, the multiscale only be achieved if units in general equations were treated.

rotating cylinder

i want to simulate a rotating cylinder containing fluid . and this whole cylinder is also rotating about an axis which is out side the cylinder..any one can help me out?

Jiangping Xu's picture

Reply--Abaqus quasi-static induced numerical damping

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The damping ratio, used in quasi-static problems, such as sheet forming, stamping, forging, is that role, b, shown in the following equation

Ma+bCv=P-F

For the problems mentioned above, the value of b is about 0.1.  if dynamic explicit method is employed, the simulation may encounters steady problem, while convergence problem for implicit method employed.  I think, you can search some articles on damping in sheet metal forming, then you will understand the effect of this damping ratio.

mechevikas's picture

Laser machining of composite materials..

hai

can we do laser machining of composites materials like glass fiber etc.. from simple laser machine or we have to use special fiber laser for this..please through some light on this topic....

Alan R. S. Ponter's picture

Pleased to see

I'm pleased to see that over 600 of you have at least read some of my comments and I wouldn't be surprise if not all of you read through to the end.

Alan R. S. Ponter's picture

How do Italian Universities compare with British Universities, and the importance of Charles Dickens.

Mike Ciavarelli and I discussed the possibility of doing a comparison of Italian and British Universities. On reflection, I could not decide where to begin but wrote the attached. It is part personal experience, part history and part Charles Dickens who was born 200 years ago today. If you don't understand the connection, read on.

jsrivas's picture

The Cost of Knowledge

http://thecostofknowledge.com/

If research projects are funded by public money, shouldn't their
results be available to the public at a reasonable price? or even free
of charge?
To prevent the monopolization of the scholarly record, read, think, and, hopefuly, support this cause. It is all I ask.

PCB Thermal simulation

Hi guys, I'm a Telcommunication Engineer and I'm looking for an open source software to perform thermal simualiotn on a PCB (printed circuit board) with some LDMOS transistor installed to better understand the thermal behaviour.

Can you plese suggest me once?

 Thanks

 Davide 

Teng Li's picture

Number of iMechanica Registered Users exceeds 30,000

  

As of 8 January 2012, the number of registered users of iMechanica exceeded 30,000 , the total number of posts is 11,690, the total number of comments is 18,000.  After five years and four months since its launch, iMechanica still keeps growing steadily.

Founded in September 2006, iMechanica aims

Mike Ciavarella's picture

profumomontinapo

Taxonomy upgrade extras: 

REGARD TO MY M-TECH PROJECT

HI SIR/MADAM,

THIS IS SURYATEJASWI , MAM/SIR I NEED TO KNOW HOW DO I USE TIE CONSTRAINTS TO TIE UP THE SURFACE SKIN OF A CURVED PANEL AND STRINGER IF THEY ARE TO BE A SHELL ELEMENTS... PLZ SUGGEST ME WITH THIS PROLEM AND ALSO WITH MY PROJECT..

HOPE FOR THE BEST NEED

THANK YOU

wenjun.lu@ntnu.no's picture

abaqus exec\pre.exe aborted with system error code 5.

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Dear all

 I encouter this problem when I utilize finner mesh,while no such error was reported if a coarse mesh was used.

Could it be a problem of my computer's memory? But which memory exactly? (physical memory or the space for storage)

 I feel the calculation has not yet fully utilized my computer's physical memory according to the task manager. 

 

So, my questions are:

1. where possibly would the problem be?

2. how can i possibly address them?

 

Thanks in advance!

 

Regards

 

How to estimate crack growth propagation using the maximum tangential stress criterion method?

Hi All  Currently I am running FE modelling using linear elastic fracture mechanics approach to estimate crack growth propagation in a web plate of box girder in an existing bridge deck. The FE model includes 3D solid element. The crack growth direction is expected to follow in a plan perpendicular to the maximum principal stress.  As I know there are many methods can be used to estimate the direction of crack during propagation. My question is about the maximum tangential stress criterion method.

dileepade's picture

need help in ansys

sir,

I need to find out kinetic energy of the element in the harmonic analyis problem of a plate.

i am using ansys command...in /post1

etable,KE,KENE

but no data is stored on the lable KE

please help and suggest some other means to do the same...or the correct method of issuing this command ..

 thanks

dileep

 

 

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