Summary
Fatigue is a cracking mechanism that results from cyclic stresses that are lower than the normal tensile fracture stress. These cyclic stresses may be associated with pressure fluctuations in vessels or piping, rotational loads on a pump or compressor shaft, high frequency vibration-induced dynamic loading or flow induced vibrations. The mechanism involves both crack initiation and crack growth to failure. Final failure is either by brittle fracture or by ductile overload due to loss of load carrying cross-section.