Crack penetration in cohesive zone models

vinh phu nguyen's picture

Hi all,

I am conducting some cohesive crack simulations within the framework of XFEM. The cohesive model is an initially rigid traction-separation law for mode I.  In order to deal with negative values of the normal sepration/jump, I use a penalty stiffness K.

The example is pretty simple: an un-notched three point bending test where a crack is initiated at the bottom edge of the beam and grow vertically upwards to the upper edge. During the simulation, some negative jumps are observed. The convergence is very much dependent on the penalty stiffness K used. Even for some cases, no convergence obtained at all. I tried K from 10^3 to 10^10.

Could you please share your experiences in dealing with crack penetration in crack grow simulation?

Many thanks,

Phu


Pengfei Liu's picture

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The parameter selection in cohesive modeling is a difficult thing in deed and also a defect for promoting the crack propagation simulation. Now their is not a good method to solve this problem. I think you can only try to adjust these parameters such that the theroretical results match the experimental results. In fact, the parameter identification is also a deep topic. 

 


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What do u exactly mean by sending a website in chinese?