Identification and updating of AB 204 helicopter blade F.E. model by means of static and dynamic tests

In this paper, the structural properties of the AB 204 helicopter rotor blade, whose characteristics are completely unavailable, have been identified through both static and dynamic tests, and by a further structural updating of the corresponding Finite Element numerical model. Under the hypothesis that the dynamic behavior of the blade is well described by a beam representation, this “ reverse engineering” analysis estimates first the stiffness distribution, along the blade span, by measuring the displacements of the structure when known static loads are applied. Then, the mass distribution is further estimated using the modal parameters achieved from experimental tests. The 1-D finite element model, obtained using these experimentally evaluated elastic and mass characteristics, has been further improved by an updating procedure based on the sensitivity of frequency-response-based correlation functions to changes in the design parameters adopted for the updating process.