initiation

G'day all

Having a metal element with a notch like crack (assume sharp one, exhibits plasticity),  what are the actual fracture mechanism (the phases the crack goes through) in the total fatigue-life. 

please comment on these scenarios:

1- crack initiation life calculated from the (S-N, e-N), then using LEFM/EPFM to determine the cycles for the crack propagation to failure...

Q/ how to find the crack length between the two phases, I mean from which stresses and at which crack length we start the crack propagation life estimation.

Dear iMechanicians,

It seems that nobody here is active in fatigue life prediction focused on the initiation period. I believe it should be here and do not understand why the fracture mechanics has its place here but the initiation of cracks has been forgotten. Although cracks are very interesting there is a lot industrial sectors, where they are not wanted. Is not the reason of the current situation that the available computational tools that are free are mostly related to crack growth?

Regards,

Jan Papuga