# SIF,COD and Critical Flaw size for a pressured pipe with axial and circumferential crack in ABAQUS

Hello All,

I'm new user in ABAQUS and I want to simulate and verify a critical crack-size in a pressurized pipe with axial and circumferential crack. Also, an important aspect, the crack is through-wall thickness. So, I'm faced with some doubts about its implementation in ABAQUS as following:

1 - Can I model the through-wall crack with shell ements based on line-spring (element LS3S)?

2 - When I compute the stress intensity factor, the result that I get for axial crack, for example, is related to internal pressure as the loading. It is not related to hoop stress. It seems to me strange, because the loading on the material is the hoop stress. Therefore, the results for K should be close to hoop_stress*sqrt(pi*a), where "a" is the half-length of crack. Why does it occur?

3 - I'm trying to evaluate from the code the COD(crack-opening displacement), but it gave me back that this result is not available. I didn't understand why. Some one knows a good way to get this result? I'm trying to write the transcript without pre-processor use.

4 - I'm trying also to perform a parametric analysis in ABAQUS and I realized that it is possible through Phyton interaction with the code. But, I tried to run the example models about parametric studies and I could't open and load them. Some one also have a clue how can I do that?

5 - Finally, some one knows how can I incude the fracture toughness of the material in ABAQUS? I mean, is there any way to get the critical stress intensity factor or resistance curve of the material through the simulations? i need that in order to evaluate the critical length size of the crack.

Thank you so mch for the help,

Odilon.