Hybrid calibration of aeronautical structures instrumented with strain-gages for load prediction

This paper presents a hybrid methodology for loads measurement on aircraft structures. It is based on both experimental data from the actual structure and numerical prediction from finite element models. The model is firstly adjusted based on a reduced amount of experimental data, so it can predict the structure load response in terms of simulated strain-gage bridge responses. Once adjusted, the model is loaded at several points while gathering the corresponding simulated strains responses. Based on regression analysis, the calibration coefficients are established to be used for in-flight load measurements. Comparing with the conventional calibration method, purely based on experimental tests, the new calibration methodology requires less calibration load cases, which makes the test setup also simpler. The new calibration method is applied to a horizontal empennage from a commercial aircraft, for which the conventional calibration was previously conducted, providing therefore the reference for both flight and ground test comparisons. A good correlation was found between the loads estimated by the conventional calibration and present method. Nowadays, virtual tests are getting importance for validation and demonstration purposes, and this work is adherent with this tendency.