Identification of electromechanical properties of piezoelectric structures through evolutionary optimisation techniques

In this paper a non-destructive method to predict the whole three-dimensional set of electromechanical properties of active plate structures is presented. Since the elastic properties of the patches, along with their piezoelectric properties, have significant effect on the dynamic response of the global structure, the inverse problem of the identification of those properties is stated as a constrained minimisation problem of an error function expressing the difference between the measured eigenfrequencies and the corresponding numerical values. Thus, the adopted strategy relies on the dynamic response of the structure in terms of undamped natural frequencies and makes use of a global optimisation technique. To this purpose, a 3D finite element model is used to model the piezoelectric sensors, while an improved genetic algorithm is used as the optimisation tool in order to perform the solution search. The results are demonstrated through a simulated test case, that shows the accuracy of the method.