Research on compiling fatigue load spectrum of individual aircraft and analysis of fatigue life based on flight data

Compiling fatigue load spectrum is the precondition and basement of fatigue life prediction, simulation experiments and fatigue strength analysis of aircraft. The method of air fleet life is used on management of homotype aircraft life for a long term, that is the process of achievement on safe life index by fatigue experiment of aircraft overall dimension on condition of standard fatigue load spectrum. However, individual aircraft life monitoring could represent difference on flight environment and pilot manipulation of each aircraft by real load course of aircraf, which differs from the previous method. And this could lay a foundation on having the damage informations in hand during the service life of individual aircraft timely. Furthermore, flight data system of aircraft equipment, which offer the abundant data on compiling individual fatigue load spectrum. Based on the parameters of overload on center of gravity etc., this paper firstly adopted the method of rain-flow count to register the amplitude and mean of overload data on each cycle by preprocessing of flight data. Thus the overload spectrum was compiled by the means of fluctuations in center. And the fatigue life of the critical part in an aircraft was computed using the local stress-strain techinique considering material memorial characteristics under the fatigue load spectrum based on flight data. Contrasting with experiment outcomes, the calculation results indicated the probability of aircraft life-saving, which was also the groundwork to service-life monitoring of this type aircraft.