High Cycle Fatigue Assessment of Piping Structures Using the Rainflow Counting Method

Engine accessory piping systems are prone to high cycle fatigue failure due to the effects of random vibration. In this study, finite element analysis and material testing were conducted to ascertain the fatigue strength of a specific engine accessory piping system. The distribution of equivalent stress on the structure was determined by frequency domain analysis, and the locations deemed to be dangerous were identified. The time-domain response of the stresses at the locations identified as hazardous under random vibration loading was obtained by time-domain analysis. The time-domain response was decomposed into load combinations by combining it with the rainflow counting method. The tensile and fatigue tests of the piping material were completed, and the Goodman curve and the fatigue constant life curve of the material were determined. The constant life curves were then combined with the load combinations to make a final judgement on the high cycle fatigue strength of the pipeline under random vibration loading. Calculations show that fatigue damage to the pipeline will not occur at the current random vibration intensity.