Piezoelectric Modal Sensors for Two-Dimensional Structures

Abstract

Using the orthogonal property of eigenfunctions, piezoelectric modal sensors for one-dimensional members were created by shaping electrode patterns proportional to modal strains. However, it is not easy to apply the same concept to two-dimensional structures due to the difficulty in implementing location weight needed for signals. Therefore, nonlinear optimization scheme is employed in this paper to design modal sensors for two-dimensional structures. For a given electrode pattern, the signal contributed from each mode is found by integrating the corresponding free surface charges on the sensing electrode. Then the modal sensor is obtained by modifying electrode pattern to achieve required relative signal strength for different modes. Sensors that are capable to sense or filter out the signal generated by a specific mode can be developed. A two-dimensional aluminum plate coated with PZT layer is adopted as an example. Mode shapes are found with finite element analysis. Modal sensors are designed successfully and mode- reject filters are also demonstrated.