\(l\) |
surface crack length |
\(\text{\ l}_{\text{av}}\) |
average length of the existing surface
cracks |
N |
number of cycles |
\(\text{\ N}_{\text{f\ }}\) |
number of cycles to failure |
Z |
number of existing surface cracks |
Δm ,Δc |
extent of monotonic and
cyclic, respectively, crack tip plastic zone |
δ, Δδ
|
maximum and cyclic, respectively, crack tip
opening displacement |
σ |
current applied stress amplitude |
σo |
initial axial stress
amplitude |
σy |
monotonic yield stress |
σcy |
cyclic yield stress |