iMechanica - fracture mechanics - Comments

excellent

Farid Touaiti — Fri, 29 Aug 2008 06:12:24 -0400

thank you very much.

Blogging with LaTeX!!

HY Shadow Huang — Thu, 21 Aug 2008 17:20:09 -0400

Hi Alex,

Thanks for this info. Finally I am able to type math entries in the blogs. I've tried it out and it worked perfectly.

Thanks again!!

force-displacement curve vs traction-separation curve

Zhigang Suo — Thu, 21 Aug 2008 13:46:35 -0400

Dear Samuel: Thank you for your comments. Other users have also reported difficulties with posting comments on iMechanica. The difficulties seem to be restricted to users with Internet Explorer as their browser. This problem with posting comments can be fixed. I have also put this link on the right side of iMechanica, under Quick Guide.

Now let me turn to your question about the mechanics of bridged cracks. Force-displacement curve is what you measure when you apply a mechanical force to your specimen. The two faces of the crack separate, but part of the crack may be bridged. Many models assume a relation between the separation of the crack and the traction in the bridge.

In a typical model, the separation-traction relation is given as an input, and one can calculate the force-displacement curve. In an experiment, of course, you measure the force-displacement curve, and try to infer the separation-traction relation.

These basic ideas are reviewed by G. Bao and Z. Suo, Remarks on crack-bridging concepts," Applied Mechanics Review45, 355-366 (1992). Many other people have worked on the subject, too. Let's hope someone can direct you to papers more specific to your experiment.

Traction-separation law

Sergej Tarasov — Sun, 27 Jul 2008 08:07:22 -0400

From my experience, the shape of traction-separation curve has little effect on the load-displacement curve for linear materials. The initial stiffness of the cohesive elements should affect the slope of the first part of load-displacement curve, and the "sharpness" of the peak load value depends on the strength (maximal traction) of the elements. As the crack propagates all curves should practically coincide, as we see in Case 3. But results for Case 1 look quite strange.

Excellent work

yanyabin — Sat, 26 Jul 2008 10:00:23 -0400

You have done an excellent work!

Here what I want to say is that I am also working on using cohesive elements to simulate the delamination process in pizeoelectric thin films. Layers in this kind of thin films are in micrometer or even nanometer scale. What's more, my simulation is also based on a sandwiched-cantilever experiment.

In my simulation, some different kinds of cohesive zone models are used and their traction-separation laws are programmed in the user subroutine in ABAQUS. By reading your paper attached in your blog, I know that the bilinear cohesive zone model was used in your simulation. So, did you applly other kinds of cohesive zone models in your simulation? Did you code their constitutive relations in the user subroutine?

Therefore, I am very interested in communicating with you about the cohesive zone models. Do you have spare time to have this kind of communication with me?

PS: My e-mail: yanyabin@gmail.com.

regards

yanyabin

Gauthier Chevallard's self introduction

Gauthier Chevallard — Mon, 12 May 2008 15:59:34 -0400

I am a Masters student in Engineering Mechanics

Student from Ecole Centrale

I am working for Dr Liechti and Dr Ravi Chandar

I have to characterize the non linear viscoelastic behavior of a polymer

note

Huai Huang — Sun, 11 May 2008 08:21:26 -0400

changed some incorrect notes in ppt, maybe need more polish

term paper uploaded

Masayuki Wakamatsu — Fri, 09 May 2008 14:42:43 -0400

imechanicians & Dr. Huang,

Please find the attached EM 388F term paper.

If anyone is struggling to have cohesive element to work, please feel free to contact me.

I couldn't have made numerical analysis without generous support from fellow phd. student.

regards,

masa

Good work

Rui Huang — Fri, 09 May 2008 14:10:26 -0400

It is interesting to see how the shape of traction-separation curve affects the load-displacement response as well as the crack growth behavior.

Thanks!

Chen Shi — Mon, 05 May 2008 21:56:35 -0400

Thanks!

Presentation File Updated

Masayuki Wakamatsu — Wed, 30 Apr 2008 18:38:05 -0400

imechanicians,

Please find the attached presentation file.

masa

Term Paper Presentations on Wednesday, April 30, 2008

Rui Huang — Mon, 28 Apr 2008 18:42:34 -0400

1. The effect of free surface on stress intensity factor in 3D crack problem

2. Subcritical Cracking of Low-k Dielectrics

3. Low-Cycle Fatigue Behavior of a Lead-Free Solder

4. Fracture of Orthotropic Materials under Mixed Mode Loading

5. Numerical Method in Fracture Mechanics

6. Crack growth in linear viscoelastic media

7. Theory and analysis of a DCB specimen for determining the toughness of PC-3 Prostate Cancer

Term Paper Presentations on Monday, April 28, 2008

Rui Huang — Mon, 28 Apr 2008 15:58:26 -0400

1. Fracture Mechanics of Delamination Buckling and Growth in Laminated Composites

2. Fatigue analysis of Deepwater Risers

3. Channel Cracking in Low-k Interconnect Structures

4. Discussion of fracture criterions with the crack surface boundary conditions of piezoelectric materials

5. Application of Fracture Mechanics on Cortical Bone Studies

6. Interface Fracture – Analysis and Numerical Assessment of SAM-SAM Fracture with ABAQUS

7. Nanoindentation in experimental fracure mechanics

Comprehensive Distance Education

Noel M. Dioyan — Fri, 11 Apr 2008 09:56:43 -0400

That is very interesting idea sir,if imechanica can provide a distance education from all field of engineering mechanics.The whole world is watching all the comments and suggestion in this site. Maybe, We here from asia can be benefited in your great proposal " Education without boundary" reagardless of distance,races,ethnics and culture..

your title

Rui Huang — Mon, 07 Apr 2008 22:27:28 -0400

Suk-kyu,

Please add "EM 388F Term Paper:" at the beginning of your title.