Preparing an article on fatigue crack propagation , I am wondering what is the most appropriate /most commonly used expression for

R = Kmin/Kmax?

--> R-ratio (Well, the R already stands for ratio, doesn't it ?)

--> load ratio (actually, it's not about load in fatigue crack propagation, it is about stress-intensity...)

--> stress-intrensity ratio (seems to be correct, but, eh, such a long expression, you'll twist your tongue reading it...)

Please, can you hekp me out? Which expression do you use?