Abstract:
In this paper, a methodology to derive loads to apply to a full scale fatigue test from flight test data is presented. Bell model 505 tailboom is used to illustrate the methodology. First, the tailboom instrumentation for flight testing is described. A complete Load Level Survey is performed to gather the data required for the fatigue test. Then, the whole flight test data (18,000,000 data points) is reduced to a critical convex envelope (roughly 5,000 data points). To further reduce the loads data set to a manageable number for a fatigue test, a Finite Element model is built to obtain relations between applied loads and stresses at specific locations on the tailboom. A total number of 6 load cases are finally identified and a proper loading sequence is defined according to various considerations. Finally, the whole methodology and limitations are discussed.