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Modelling Crack Tip area

Hello everyone

 

I am using FEMAP v11.3 with NX NASTRAN.

I am trying to analyze a cracked model. I found at the NX NASTRAN LIBRARY, the special element for the crack tip area, CRACK2D. Unfortunately the specific element does not exist at the FEMAP element library.

 

Could you please advise me if there is a way to use this specific element with FEMAP v11.3?

How can I import or call this element from NASTRAN to FEMAP?

 

Thank you very much in advance.

Best Regards

Antonis

3 REPLIES

Re: Modelling Crack Tip area

My understanding is that the CRACK2D elements are used by the Nastran solver SOL401 MultiStep Non Linear Solver. Unfortuntely this is not directly available for standard FEMAP. With the new FEMAP Nastran Desktop extension you can generate a Nastran dat file within Femap and link it to SOL401 as part of the  NX CAE Advanced Nonlinear modules. You would need to edit the FEMAP Dat file to add in the element cards for the CRACK2D elements.

 

SOL 401 will calculate crack tip stresses or J-integrals at a crack but not simulate crack growth. For FEMAP users you need a thrird party program called ZENCRACK which will take the SOL401 results, calculate where the crack will grow next, generate a new mesh and submit it to SOL401 for updating stresses etc and in this manner you can model crack growth.

 

Of course SOL401 is available in the Advaced Nonlinear modules in Simcenter 3D. In addition Simcenter can also interface with the Samcef FEA NL solvers which will also simulate the crack tip stresses and crack growth but using a module called XFEM to do the role of ZENCRACK with NASTRAN SOL401. 

 

Hope this helps.

 

Regard

David Christensen

EdgePLM

Solution
Solution
Accepted by topic author Antonis_Ch
a week ago

Re: Modelling Crack Tip area

The CRAC2D element is the old Nastran crack element which has been around a long time and works in SOL 101. It is not supported by Femap, so you would need to create the nodes required manually, then using "start text" in Femap create the CRAC2D element. The output would then be found in the F06 file only.

If you use this element or the 3D verison, it is critical to make the element perfectly square to get good results.

See the Nastran documentation and look at the Element Library Reference for details on the element.

 

SOL 401 will have new crack element options including J integral as mentioned.

 

Regards,

 

Joe

Re: Modelling Crack Tip area

David and Joe thank you very much for your reply. 

I will try to follow your advices.

 

Regards

 

Antonis