Very high cycle fatigue measuring techniques

Ever since high-strength steels were found to fail below the traditional fatigue limit when loaded with more than 108 cycles, the investigation of metals’ and alloys’ very high cycle fatigue properties has received increased attention. A lot of research was invested in developing methods and machinery to reduce testing times. This overview outlines the principles and testing procedures of very high cycle fatigue tests and reports findings in the areas of crack formation, non-propagating small cracks, long crack propagation and thresholds. Furthermore, superimposed and variable amplitude loading as well as frequency effects are reported.

► Review of VHCF-testing machines, measuring techniques and evaluation procedures. ► Advantages and restrictions of the ultrasonic fatigue testing technique. ► Existence or non-existence of fatigue crack growth thresholds and endurance limits in the VHCF regime. ► Interior and surface crack initiation and propagation, non-propagating small cracks. ► Variable amplitude loading, frequency effects.