ABSTRACT
Using a piezo-electric fatigue machine, it is possible to determine the fatigue crack growth curve, DK versus da=dN, including the threshold regime to growth as low as 1012
m=cycle. It will be noted that the fatigue thresholds are basically the same in both conventional and resonant fatigue if the computation of the stress intensity factor K is correct. One objective of using the piezo-electric fatigue machine to determine DKth is to save time and money, but it is also of interest to note that a piezo-electric fatigue machine is very effective both for a wide range of cyclic load ratios-R¼1 in tension-compression and R> 0.8 with a high mean stress.
