I use the contour integral method in ABAQUS to calculate the J-integral of CT specimen(2D). The material is elastic-plastic, and the constitutive model is established by using incremental plasticity. Considering geometric nonlinearity, Nlgoem is On in the Step Module.The results indicate that the J-integral is relatied to the path, and some J-integral values are negative.
I don't know how to solve this problem. I will be appreciate that if you can help me.
PS:
The CT model, the shape of blunted crack, and the results of J-integtal are shown below.
Hi Tong Sun,
Try to remesh the crack tip vicinity to ensure fully circular paths enclosing the tip.
Please, take into account that boundary on whih you perform J-integral should be sufficiently small with respect to the computational domain (where, exactly you should evaluate the strain energy rate), but suitably large to account for all significant stress/strain gradient affectind the mechanical behavior ariund edge.
Giuseppe Vairo
Thank you for helping me!
The length and width of the CT specimen are 75mm and 72mm respectively, and the radius of the blunted crack is 0.0025mm. The number of contours is 60, and the distance between the first contour and the crack tip is one tenth of the radius of the crack tip(0.00025mm). I think it is enough to describe the significant stress/strain gradient.
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