Analysis of Smart Structures with Piezoelectric Strips Subjected to Unsteady Aerodynamic Loads

Abstract

A method using piezoelectric strips bonded on thin structures to detect the presence of cracks for structural health monitoring is presented in this paper. The method uses pairs of piezoelectric strips glued at the same location on the two sides of the structure and is based on the measured voltage difference between the two strips of a pair, which is proportional to the differential strain changes due to the presence of a crack. The structural analysis presented in this paper uses a nonlinear model for the cracks and a finite element formulation for the piezoelectric strips coupled with the structure. A panel method is used to determine the unsteady aerodynamic loads acting on the oscillating wing structure. This study includes the dynamic analysis in the frequency domain of a cracked plate undergoing forced flexural vibrations in a range of frequencies produced by a pair of piezoelectric actuators. The dynamic analysis in the time domain is also performed for the oscillating structures with piezoelectric strips subjected to mechanical or aerodynamic unsteady loads. It was found that this method has a good sensitivity in detecting the cracks in the wing structures subjected to oscillatory aerodynamic loads.