iMechanica - project - Comments

One Quick Note

Matt Pharr — Tue, 18 Nov 2008 23:39:38 -0500

I was reviewing Pawel's project and found something that might pertain to yours as well. If you are going to try to model the 300-400% volume strain, you may want to try using an Eulerian approach. If you look in the ABAQUS 6.8 documentation under Abaqus Analysis User's Manual in Analysis Techniques and then Section 13.1.1, it states that an Eulerian approach may be used to effectively handle large deformations. I believe this feature may not be available in Version 6.6 (it is not in the 6.6 documentation) but should be available in version 6.8 (if you can find access to it . . . ). So, I would suggest looking into this feature. Anyways, I am not going to waste your time posting some review article since you have probably already read it because I know you are doing this for your research. So, just this one suggestion.

http://www.hlrs.de/organization/aw/services/cae/app/abaqus/Documentation/docs/v6.8/books/usb/default.htm

-Matt

"Contents are Hot"

Matt Pharr — Tue, 18 Nov 2008 23:30:47 -0500

Hot coffee is a serious problem with much work being done on it in terms of legality

http://64.233.169.132/search?q=cache:GbYEBcPI-x0J:www.okbar.org/public/judges/mcdonaldsoutline.pdf+warning+contents+hot+coffee&hl=en&ct=clnk&cd=4&gl=us

and design

http://www.gizmodo.com.au/2007/06/because_contents_are_hot_warni.html

Actually in all seriousness I have found this topic (sloshing of a fliud) interesting since I did a problem on a partially filled milk tanker in introductory fluid mechanics. One thing that you might want to think about though is how ABAQUS will handle this problem. I looked through the documentation and initially found that solving this problem might not be possible to do in ABAQUS. If you look in the ABAQUS 6.8 documentation under Abaqus Analysis User's Manual in Analysis Techniques and then Section 11.5.1, one can see that it is very easy to model a fluid-filled cavity in Abaqus. However, it mentions in this section that the technique used to do so cannot be extended to a partially-filled container; it even directly says that this cannot be applied to sloshing. However, upon further investigation, I found that in Section 13.1.1 that an Eulerian approach can effectively handle liquid sloshing. So, this will be very important to your project. I have also found that this section was not included in the 6.6 documentation, so this feature may not be available in that version. You should definitely look into this and see if you need to find access to Version 6.8.

http://www.hlrs.de/organization/aw/services/cae/app/abaqus/Documentation/docs/v6.8/books/usb/default.htm

Also, I have found an article that may be of interest to you. It gives an overview of different numerical techniques (11 of them) that are used to model sloshing of liquid cargo in ship tanks. Here is the link

http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V41-3XRG6T9-5&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=33b663f98abf83a045e45543293e0e1f

-Matt

Interesting project about an important issue of microelectronics

Sung Hoon Kang — Tue, 18 Nov 2008 11:12:59 -0500

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It’s an interesting project that studies one of the
important issues of microelectronic devices. It would be great to see how the
thermal stress profile will appear with temperature change during operation. I
have a couple of comments from one of the reference in the proposal [1] and
would like to suggest two potentially interesting references [2-3].

According to the paper by Prof. Tu, electromigration is
enhanced by tension but retarded by compression at the cathode and it is vice
versa at the anode. So, he suggests that “a favorable condition should be the
electron current entering the joint from the compression region and leaving
from the tension region.” [1] Thus, it would be interesting to find the tension
and compression regions at both cathode and anodes from the numerical
calculation which can be potentially useful for utilizing the effects that the
author mentioned. In addition, as the author mentioned, it would be also
interesting how the back stress, which can be built up in a flip chip solder
joint for the case of underfill, may interact with thermal shear stress.

As I search literatures about thermal stress in
solder-joint, I found two papers which can be helpful references. Wu et al. studied
the thermal stress in a Sn3.5AgCu half-bump solder joint under a
current stressing [2]. They reported substantial thermal stress accumulation around
the Al-to-solder interface, with a maximum stress of 138 MPa and the stress
gradient in the Ni layer of 1.67´1013 Pa/m resulting in a
stress migration force of 1.82´10−16 N, which is
comparable to the electromigration force, 2.82´10−16 N. In addition, Liu
et al. did 3D modeling of electromigration in IC device and solder joint (SnPb and SnAgCu lead-free solder materials) under the
combination of high current density, thermal load and mechanical load [3]. They
calculated the temperature, stress, atomic flux distribution in a packaging and
predicted void formation.

As a last comment, after doing thermal stress calculation, if
possible, it would be great to compare the numerical analysis result with the
experimental result for better understanding of the phenomena happening in the
flip-chip solder bumps during operation.

References

[1] K. N. Tu, “Recent advances on
electromigration in very-large-scale integration of interconnects”, J. Appl.
Phys. 94, 5451 (2003).

[2] B. Y. Wu, Y. C.
Chan, and H. W. Zhong, M. O. Alam, J. K. L. Lai, “Study of the thermal stress in a Pb-free half-bump solder joint under
current stressing”, Appl. Phys. Lett. 90, 232112 (2007).

[3] Y. Liu, L. Liang, S. Irving, T. Luk “3D Modeling of electromigration
combined with thermal–mechanical effect for IC device and package”,
Microelectron. Reliab. 48, 811 (2008).

Why Man Created The Travel Mug...

milnes — Mon, 17 Nov 2008 23:17:01 -0500

Pawel,

I nearly spill my coffee all the time too.

This is an interesting topic, and one that is fairly important to many areas of mechanical engineering. Espescially important to vehicle dynamics, violent sloshing can radiaclly change a vehicle's performance envelope in dynamic circumstances.

I found an interesting article on Google Scholar that talks about seismically-excited sloshing. It might be a good reference for dealing with multiple simultaneous forcing functions; it's linked below.

-Tom

http://doi.wiley.com/10.1002/(SICI)1096-9845(199607)25:7%3C653::AID-EQE513%3E3.0.CO;2-H

Great Idea

milnes — Mon, 17 Nov 2008 23:07:14 -0500

Matt,

This sounds very interesting; I wasn't aware that this sort of force was generated in traces. While I know relatively little about the area, you may benefit from the following two experimental papers. You could try to reproduce their results numerically if you want to perform a sanity check on your results. It might be valuable to vet your approach with real-world results.

-Tom

http://link.aip.org/link/?JAPIAU/73/3790/1

http://link.aip.org/link/?APPLAB/74/2945/1

Yuhang - Yes, I will

bjordan555 — Mon, 27 Oct 2008 10:15:31 -0400

Yuhang -

Yes, I will explain the differences, and will include this in my project report.

Yes! You can use PDF

Yuhang Hu — Tue, 21 Oct 2008 09:23:33 -0400

Yes! You can use PDF version.

Yes! You are welcome to

Yuhang Hu — Tue, 21 Oct 2008 09:20:10 -0400

Yes!

You are welcome to use Comsol for your project.

So we all can learn something new from you.

By the way, could you explain what the distinct advantage of Comsol is compared with other sofware? Thank you!

Comsol instead of Abaqus?

bjordan555 — Mon, 20 Oct 2008 22:23:28 -0400

I am an experienced Comsol user, and would like to use this software instead for my project. The quality of the output and its ability to solve the equations are both adequate for my project. Do you approve of this change as well?

Document Formats

bjordan555 — Mon, 20 Oct 2008 22:20:58 -0400

I do not use word or powerpoint; Can I post my report and presentation in PDF format?

fracture mechanics project

LOKESH CHOUDHARY — Sat, 11 Oct 2008 01:20:55 -0400

hello

i am lokesh,pursuing M.TECH from IIT MADRAS.i want to do project in fracture mechanics.from last 2 month i am searching for a problem.i have only 5 month to complete project.can you suggest me some project about fracture mechanics.

ialso want to know about 2d and 3d crack propagation simulation.is it good problem?can we use only matlab for crack propagation simulation?i want to know other possibilities for performing crack simulation?please help me and suggest good projects,which can be completed in 5 months.

thanks

regards

lokesh choudhary

VUMAT

doctorant59 — Fri, 21 Mar 2008 09:54:22 -0400

Hello;
I am a student in mechanical, I work on polymer materials, I order to implement the model Aruda - Boyce, I have a problem to do so. Is what you can m'aidé?
Thank you

ES 240, final project

Sunny Wicks — Sun, 13 Jan 2008 11:28:08 -0500

Here is the powerpoint of the final project, presented by Stevie Steiner and myself.

hi all

syambabu — Wed, 04 Jul 2007 12:27:50 -0400

i am sam doing Btec final year in mechnical stream,in our 4/4 first sem we have to do mini project,plz suggest a project ,im intersted in machine design

I may use this teaching method

Henry Tan — Thu, 08 Mar 2007 10:46:16 -0500

I may use this teaching method later.

I guess many instructors will post their teachings, and encourage students put their works and discussions, on iMechanica in the future.

One class involves not just the instructor, teaching assistant and students, but mechanicians from every corner of the world.