Monitoring of Fatigue Loading on Rotor Systems and Related Components

This paper gives the results of structural methods research on the subjects of fatigue cycle counting, fatigue damage monitoring, and (he effects of spectrum loading on fatigue life. An algorithm is proposed for computer processing of raw data to obtain empirical loading spectra and to estimate fatigue damage. Applications of analytical applied load spectra are illustrated. On the basis of Miner's Rule, along with the analytical applied load spectra, allowable load-cycle curves under spectrum loading are developed for various materials. Computer programs developed in connection with this research are summarized. The applications of these methods to real-time fatigue damage monitoring is discussed. Correspondence is shown between the method of this paper and the preliminary design method used by Bell Helicopter.