Article KD-4 Fracture Mechanics Evaluation

[ellameland]

Hi all,

I have a question related to the calculation of the stress intensity factor K in KD-420.
Methods for calculating the fracture stress intensity factors are given in appendix D, and I want to use the method given in D-401 - Stress intensity factors for internal radial-longitudinal cracks.

Should I here use equivalent stress values that I find directly in the FEM analyses along a path where it is most likely for the crack to occur? The stress values will be the A0,A1,A2,A3 = constants.
Or should I use the fracture mechanics module in ANSYS Workbench to find the stress intensity factor directly?

Hope someone here are experienced with this situation and can advise me!

Thanks in advance.

Elisabeth

 

[BJI]

You should extract the stresses perpendicular to the crack plane, don't bother with the FM module in Ansys. If you look at the alternate method, your through thickness stress distribution can be represented by the polynomial equation, between x/t = 0 and x/t = 1. A0 is your membrane stress, since it doesn't vary through thickness, and the A1 to A3 are the constants for the bending component.