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Objet connex can do it. But

Fri, 2014-12-19 09:02

In reply to 3D Printing of cylindrical shells with varied stiffness

Objet connex can do it. But it won't be cheap.

FEA modeling of FRP bonded RC Beams

Fri, 2014-12-19 07:33

In reply to Modeling concrete wrapped CFRP sheet using ANSYS

Hello there,

I have just started my Research on the subject matter for MS Structural Engineering. Problem is that I am not very good at modeling in ANSYS. I would really appreciate if someone could share relevent research on the captioned email address;


Thu, 2014-12-18 08:46


STRESS TRIAXIALITY is the ratio of the hydrostatic part of the stress to the equivalent stress.
In 1-D tensile test, STRESS TRIAXIALITY is 1/3 upto necking, as necking starts the state of stress is not 1-D, so TRIAXIALITY is no longer 1/3.




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Wed, 2014-12-17 19:20

In reply to Lecturer (Assistant Professor) in Geotechnics position available at University of Edinburgh, Scotland

Vacancy for Lecturer or Senior Lecturer in Structural Engineering at the University of Edinbrugh, Scotland, UK

The School of Engineering at the University of Edinburgh in Scotland has five vacancies for Lecturer (equivalent to US Assistant Professor)  or Senior Lecturer (equivalent to US Associate Professor). Three of the posts are in Chemical Engineering, one in Mechanical Engineering and one in Structural Engineering, applicant with a strong computational structural mechanics background will suit the Structural Engineering post. For further details please go to this URL



Measurements of critical separation of cohesive laws

Wed, 2014-12-17 15:30

In reply to About the critical opening value in cohesive models

Hi Brick,

I don't know about critical separation for metals, but based on my experience it is very material system dependent so that it is difficult to make general conclusions regarding the magnitude of the critical separation. You need to measure it for the material in question.

We have measured the critical separation a number of ways. Probably the most accurate way is in-situ observations of the crack tip by microscopy. We have conducted fracture mechanical tests using DCB specimens loaded with pure bending moments in an environmental scanning electron microscope - this provides stable crack growth and thus facilitates in-situ observations. For brittle materials (e.g. brittle adhesives) it appears that the critical separation is in the order of one micron Goutianos and Drews (2007). For composite materials we often find that the fracture process consists of a crack tip region (where the critical separation is about one micron), and a bridging zone where the critical separation can be much larger, e.g. in the order of 150 micron, see Goutianos et al. (2014).

We can also obtain the critical separation from macroscopic experiments where the crack tip opening displacement is measured e.g. by an extensometer mounted across the crack faces at the end of the cohesive zone. For a "ductile" polyurethane/steel interface we found the critical separation to be in the range of 1.7 - 3.3 mm, highest for the highest opening rate (Sørensen, 2002). For an ("brittle") epoxy/steel interface we found that the critical separation in the order of 0.1 mm (Högberg et al., 2007). For crack growth parallel to the fibre direction in unidirectional fibre composite (intralaminar cracking or delamination) fibre composites can develop large-scale crack bridging by long fibres. Then we found the critical separation under Mode I to be in the order of 3 mm (Sørensen and Jacobsen, 1998; Sørensen and Jacobsen, 2009). 

Best regards, Bent

Goutianos, S & Drews, JM 2007, 'Estimation of interface cohesive laws by digital image correlation'. in BF Sørensen, LP Mikkelsen, H Lilholt, S Goutianos & FS Abdul-Mahdi (eds), Interface design of polymer matrix composites - mechanics, chemistry, modelling and manufacturing. Proceedings. Risø National Laboratory, Roskilde, pp. 181-190.

Goutianos, S, Arévalo, R, Sørensen, BF & Peijs, T 2014, 'Effect of Processing Conditions on Fracture Resistance and Cohesive Laws of Binderfree All-Cellulose Composites' Applied Composite Materials, vol 21, no. 6, pp. 805-825., 10.1007/s10443-013-9381-0

Högberg, J. L., Sørensen, B. F., and Stigh, U., 2007, "Constitutive behaviour of mixed mode loaded adhesive layer", International Journal of Solids and Structures, Vol. 44, pp. 8335-54.

Sørensen, B. F., 2002, "Cohesive law and notch sensitivity of adhesive joints", Acta Mater., Vol. 50, pp. 1053-61

Sørensen, B. F. and Jacobsen, T. K., 1998, "Large scale bridging in composites: R-curve and bridging laws", Composites part A, vol. 29A, pp. 1443-51.

Sørensen, B. F., and Jacobsen, T. K., 2009, "Delamination of fibre composites: determination of mixed mode cohesive laws", Composite Science and Technology, Vol. 69, pp. 445-56.


Good evening Brick, :)

Wed, 2014-12-17 15:07

In reply to About the critical opening value in cohesive models

Good evening Brick, :)

Roughly speaking, the value of critical opening is in the order of Gc/sigma_yield (material toughness divided by its yield strength).

Hope it helps,

SABIC Technology Internship Program

Wed, 2014-12-17 14:39

In reply to SABIC Technology Internship Program, Summer 2015

Students with experience in fracture mechanics are encouraged to apply.

I fitted my uniaxial tensile test with mooney

Tue, 2014-12-16 18:56

In reply to cylindrical flat-ended tip indentation on Rubber

Hello Amir,

I guess you already master using ANSYS software. Right now, i need to simulate tensile behaviour of my material by using ANSYS 15 in order to observe the crack formation and ductile behaviour of the material. However, when I simulate it, the result is not what I'm expected. Can you help me with this?


FRP wrapping column

Tue, 2014-12-16 11:46

In reply to Wrapped Concrete


I'm modeling FRP Reinforced Concrete column and I'm new in ansys.

would you please Email me some pdf. I Appreciate your help. my email is

Best Regars

Objective rate of stress

Mon, 2014-12-15 19:59

In reply to Why rate equations in Nonlinear FE?

I wrote up the notes for my lectures on frame indifference and postes them online.  Several people made comments.  Both the comments and the notes might contribute to this thread of discussion.  

email alert

Mon, 2014-12-15 14:44

In reply to RSS feed?

Actually there is an email alert for JAM. You can find it right on the journal homepage:

The problem fixed just by

Mon, 2014-12-15 06:12

In reply to Immediate help on abaqus subroutine execution

The problem fixed just by copying the 'cmd.exe' file into the abaqus installation directory

Initial papers of EML are freely accessible. They look beautiful

Mon, 2014-12-15 05:57

In reply to EML is born

Thank you, Jimmy, for your leadership and for taking us this far.  Heartiest congratulations on your new position as Vice Provost at Carnegie Mellon University!  Look forward to hearing about your new experience.

A note for readers:  All initial articles are freely accessible. For example, here are Manoj Chaudhury’s paper on coalescence of drops, and Jian Ping Gong’s paper on stress generation in hydrogels.   More papers are in the pipeline. They will be posted on the web page of recent papers.  I have put this page on the home screen of my iPad.  The HTML files of the papers look great.

Please help us promote EML by sending the link to your friends.

RSS feed?

Sun, 2014-12-14 20:29

In reply to Statistics of 2014 publications in Journal of Applied Mechanics

Dear Prof. Huang, I tried for some time to add JAM into my reader but wasn't able to find a good way to track the latest articles, is there a rss feed for the journal, or other ways to do so?  Thank you!     -Kejie

Great job, Yonggang!

Sun, 2014-12-14 14:16

In reply to Statistics of 2014 publications in Journal of Applied Mechanics

Dear Yonggang:  Thank you so much for your work on JAM.  We are excited to see our paper in print so rapidly.  The jounral looks beautiful. Students here are eager to submit papers to JAM.  We at EML have much to learn from you. 

Hello Yi,

Fri, 2014-12-12 17:47

In reply to Simulation of composite delamination caused by impact

Hello Yi,

You will need duplicate nodes at the interface between layers. I guess there might be some easier way to create duplicate nodes but you can model your layers separately, i.e., create separate solid geometries offset from each other. Now mesh all these geometries with one element through thickness and translate your layers (mesh) such that they overlap but you still have duplicate nodes. Then, you can define your tiebreak contact. If you have a lot of layers, then it's time taking. There might be a simpler way too.

PhD and postdoc positions available in the Netherlands

Fri, 2014-12-12 09:37

In reply to Postdoc and PhD positions in computational modeling

Applications are invited for one PhD  and one postdoc positions in the area of computational mechanics of materials, at Delft University of Technology, in the Netherlands.

openings in computational mechanics

Fri, 2014-12-12 09:34

In reply to Postdoc and PhD positions in computational modeling

Applications are invited for one PhD  and one postdoc positions in the area of computational mechanics of materials, at Delft University of Technology, in the Netherlands.


Fri, 2014-12-12 07:32

In reply to Stress Triaxiality

I am sure that you can find numerous literature on the topic available.


During my thesis work, I have selected these two, as I have found them relevant:

-  Thaulow C, Østby E, Nyhus B, Olden V, Zhang Z. The Philosophy Of Constraint Correction. 2nd International Symposium on High Strength Steel, April 2002, Stiklestad, Norway.

-  Schwalbe K-H,  Newman Jr. J, Shannon Jr. J.Fracture Mechanics Testing on Specimens with Low Constrai Standardisation activities within ISO and ASTM, Engineering Fracture Mechanics 72, pp. 557-576, 2005.

Note that these were selected with experimentation in mind, as my M.Sc. thesis was mostly experimental.

I have come across many other good papers, but regretably do not have the references direct at hand.




Re. books on deformation gradient, tensors, manifolds, etc.

Fri, 2014-12-12 03:13

In reply to I am [still] confused about gradients, vectors, deformation gradient, etc.

Hi Stefan,

Thanks for pointing out the books. After initial browsing, I think these will require quite a concentrated reading... Let me see if I can find time for the same.

In the meanwhile, since your replies seem to have addressed most of my above questions, I am cancelling the idea of writing down my set of answers so as to get the discussion going.

Thanks, once again, for the replies and the pointers. Hope you would make yourself available if I need some help in this direction in future.






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