Problem with Cohesive Elements

[ispope]

Hi,
I am having some trouble with the cohesive elements... I am using the cohesive elements to simulate the crack growth on an aluminium thin panel using 3D elements. I have a crack in the middle of the panel meshed with 0.2 mm cohesive elements that must not be damaged under the load that I am applying. I do not know how to define the response of the cohesive elements using a traction-separation law. What should I put n the E/Knn, G1/Kss, G2/ktt fields?

Also when I try to simulate the response of the panel it acts as if the cohesive elements were not carrying load, for example, my panel has a height of 300 mm and the cohesive zone covers 200 mm with a initial crack on the middle, but the panel responses as a panels with a 200 mm crack while the cohesive elements just "follow" the deformation of the mesh without carrying load, but the do not suffer any degradation. Indeed the Status parameters has a value of 1.0 and the initiation criterion is not met.

Thank you very much

 

[jakerome]

G11 & G22 are the fracture toughness of the interface. E is the modulus when closed, typically a value like 1x10^9 is used. Try that & see if it solves the second problem.