J integral

I am actually using Abaqus' Contour Integral for the determination of stress intensity factors. But I do not know, which theory it is based on. Is it the same like the path-independent determination of J integral? Or is there a difference?

I used for the first time the CINT command with ansys, and I get strange results:

negative values

very different values for 2 adjacent nodes on the crack front

non converging values (values fluctuating from 1 contour to another, going up and down)

Also, i don't know what are the units of the J integral (I am using SI units, dimensions in mm ).  It's important to know so I can calculate the SIF

How can I know what contour gives the best result? what are the units of the Jintegral in the SI.

Anybody have some information for me?

This is a premiere: my first contribution to the new ESIS' blog announced in January. Why comment on papers in a scientific journal after they have passed the review process already? Not to question their quality, of course, but animating a vital virtue of science again, namely discussion. The pressure to publish has increased so much that one may doubt whether there is enough time left to read scientific papers. This impression is substantiated by my experience as a referee.

Hello...

Can any one help me in how to solve J INTEGRAL for simple 2D geometries.Atleast can anyone help me where can i get PDF files on J integral... Plz its urgent its a part of Thesis...   Plz post your conmments at ravikumar_04333@yahoo.com

I'm studying cracking analyses in a three point loaded specimen of a composed beam.I'm using ANSYS and i want to create codes for estimation of J integral and energy release rate in the vicinity of crack tip.After that i'll calculate the stresses and strains fields,and then i can compare the equivalent fields i retrived using CTOD  and K(I,II,III) factors (according to ANSYS algorithm).

My problem is that I'd like to find a relationship between the above mentioned quantities(J,G)  with K(I,II,III)factors.