Optimizing Mode Tuning of Guided Waves and PWAS Electromechanical Impedance for Power Efficient SHM Systems

Abstract

This study presents the use of guided Lamb wave mode tuning and electromechanical impedance (E/M) method with piezoelectric wafer active sensors (PWAS) for designing power efficient structural health monitoring (SHM) systems. The paper begins with a review of previous work on analytical modeling for power and energy of excited Lamb waves by PWAS into the structure. The study is achieved in three major parts. In the first part, Predictive modeling of Lamb wave tuning was performed analytically; then compared with measurements of both laser vibrometer and pitch catch received voltage signals. In the second part, the E/M impedance of PWAS bonded to a structure was evaluated analytically, by finite element modeling, and experimentally. In the third part, the paper describes how the E/M admittance and mode tuning were combined into the developed power model. Analytical model for power partitioning among multimodal Lamb waves was presented for 10 volts input excitation of a PWAS bonded to "- thick steel beam. Finally, a parametric study for wave power and energy was constructed for different transducer sizes and excitation frequencies. The paper ends with a summary, conclusions and recommendations for future work.