Experimental insight on an updating method with application on non-conventional wing structure

In the prediction of the dynamic behaviour of mechanical structures, the updating of the numerical model is a crucial point for industrials. Indeed, structural updating allows one to tune the numerical model to the experimental dynamic data leading first to the identification of missmodelled regions, and then to a new numerical model more representative of the experimental "real" structure with respect to the initial one. Several updating methods are available in literature most of them are classifiable as iterative sensitivity methods: the identification of missmodelled regions is obtained building a sensitivity function to structural parameters to be updated, and then performing an iterative procedure until convergence of the values of the updating parameters is reached. This paper is focused on the actual capability of the Predictor-Corrector sensitivity method to perform structural updating by means of experimental data. The main characteristic of this method is that it considers the sensitivity of two correlation functions, evaluated by the knowledge of the frequency response function of the structure: this feature is very important since the updating procedure is based only on data directly achievable from experimental tests, avoiding then numerical approximations introduced by data handling required to identify eigenfrequencies and eigenmodes of the test structure. Moreover the effectiveness of an enhancement of the Predictor-Corrector method aimed to reduce the updating parameters to be used in the iterative procedure is tested with experimental data. The experimental analyses have been carried out both on a cantilever beam and on a non-conventional aircraft wing structure with the innovative, but not so much, box-wing design. The experimental setup was formed by a Dynamic Signal Analyzer, and Transfer and Control from DIFA Measurement System, while the experimental data processing was obtained with LMS CADA-PC. The Finite Element models represent the numerical description of such structural components: the updating capabilities are investigated for different levels of structural modification experimentally obtained by changes in stiffness properties of the test articles.