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Experimental full-field response identification with limited set of operational data

Maria Chierichetti (Worcester Polytechnique Institute)

Characterization and Imaging of Structural and Material Imperfections

Mon 2:40 - 4:00

Barus-Holley 191

The accuracy in the evaluation of the fatigue characteristics of critical components in a dynamic system are closely related to the accuracy in estimating its entire response field. Structural Health Monitoring techniques represent a viable way to track the behaviour of the system during operations, but are generally limited to few response measurement locations. It is expected that the ability to extract information on the entire response based on few information will result in improvements in the estimate of the fatigue life of the system. The objective of this work is the definition and verification of an iterative procedure for the detailed monitoring of the dynamic structural response based on an experimental full-field modal model of the system on ground and a limited number of measurements in the operative condition. This preliminary ground step substitutes the need of an initial numerical model to be updated. The application of the proposed approach requires a modal characterization of the structure, achievable with a preliminary modal survey with an arbitrary large amount of experimental points, and it allows the monitoring of the structure during operative conditions by reconstructing the overall response from the measurements of few sensors. The method is formulated starting from a linear model, and it can be applied to weakly non-linear system as well, because of the iterative nature of the algorithm. The proposed method is presented as well as its implementation and several numerical test cases in order to validate its formulation. Experimental analyses are performed on a uniform beam and on a helicopter component with promising results. The approach is able to obtain accurate, full-field representations of the dynamic response, by comparing the results with the expected values achieved by the numerical simulations or with extensive measurements of the velocity field collected by a laser scanning vibrometer.