research

I am working on fracture mechanics , calculating K and J in ABAQUS
Can you please tell me how to model singularity at crack tip in Hypermesh/ABAQUS -CAE.

Do we have any tutorial available on internet ?

my id: patilmt@rediffmail.com

Thanks
Mangesh

I have used cohesive elements to create cracks now I am interested to seal the created cracks in order to study stress changes so I need to add this as a step to my analysis-

Does anybody know any trick for doing this? Can I do this by keeping the pressure inside fracture constant?-please give me comments

It seems that the measurment of local stress and strain in fatigue crack tip will be difficult. some researcher use F.E analysis method,in contrary using of numerical solution. however analytical method also has investigated. what method you can imagine? i need a brain storm in this issue.

Thank you

Hadi

We perform uniaxial tensile tests on polyimide-supported copper films with a strong (111) fiber texture and with thicknesses varying from 50 nm to 1 μm. Films with thicknesses below 200 nm fail by intergranular fracture at elongations of only a few percent. Thicker films rupture by ductile transgranular fracture and local debonding from the substrate. The failure strain for transgranular fracture exhibits a maximum for film thicknesses around 500 nm.

I have had some time to write down an informal introduction to Moving Least Squares, from my coding perspective. It is supposed to be a condensation of experiences after some years of using it, although it does not contain any new theoretical aspect.

http://www.scribd.com/doc/19409754/yanrMLS

  Dear everyone

  If we considerer a 3D fracture stress and strain field as a combination of numerous 2D fields in thickness direction, the J integral at each 2D plane can be obtained according to Rice’s definition (Abaqus and Ansys also include this function). What I concerned is the ratio of J integral at the surface of SEB or CT specimen to that at the mid-plane of the specimen. What factors have influence on the ratio? How to find the quantitive relationship between the factors and the ratio in linear elastic model?

Attention all iMechanicians!  If you have a theme you would like to see in the Journal Club next year, please feel free to:

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Let us consider interaction of two atoms/molecules/particles. The reference distance between them corresponds to zero interaction force and zero stored energy. The interaction passes three stages with the increase of the distance. At the first stage the force increases proportionally to the increasing distance: the linear stage. At the second stage the force-distance relationship deviates from the linear proportionality: the nonlinear stage. At the third stage the force drops with the increasing distance: the separation or failure stage.

I plan to submit the attached paper on quantum mechanical definition of stress in the next few weeks. Comments and feedback are welcome. Fair amount of work has been done on stress definition in the context of classical molecular dynamics (also attracting some controversies). In contrast, there appear to be several open issues in the quantum case. Hopefully, the attached paper provides a starting point.