ABSTRACT
The fatigue life of a component may be divided into three phases: (i) fatigue crack initiation, (ii) fatigue crack propagation, and (iii) rapid final fracture, each being governed by different mechanisms. The differentiation between initiation and propagation is often arbitrary, and dependent on detection sensitivity (1). In our studies on titanium, for example, crack initiation is defined as the nucleation of a detectable mode I fatigue crack, on the order of the a grain size.
