Crack width and plastic strain

Creation date: 4/28/2020 9:37 PM    Updated: 4/29/2020 7:09 AM    crack width smeared crack
Question:

Hi,

How is crack width calculated in FEA NX? Which formulation? There is correlation between crack width and plastic strain?



Regards



Answer:

Hi,

Thanks for your patience. Here is the reply from the developer.

Step 1. Convert strain(eps) and stress(str) into crack coordinate system.
          → eps_nst, str_nst

Step 2. Calculate crack strain eps_cr which does not include elastic strain.

            eps_cr(i) = eps_nst(i)-sig_nst(i)/E

           where, i = 1, 2 for two dimensional

           i = 1, 2, 3 for three dimensional


Step 3. Calculate crack width, cwitdh.

            cwidth(i) = eps_cr(i)*char_len

            where, char_len is the characteristic length of the element

           i = nn, ns, nt.


Regards,
DK Lee
Technical Manager

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