Piezoelectric Transducers Assessed by the Pencil Lead Break for Impedance-Based Structural Health Monitoring

The pencil lead break (PLB) is a well-known method for characterizing acoustic emission sensors. In this paper, we analyze the effectiveness of this method in characterizing piezoelectric transducers for structural health monitoring (SHM) systems based on the electromechanical impedance (EMI) technique. Tests were carried out on aluminum beams of different sizes, and two types of transducers were considered: 1) lead zirconate titanate ceramics and 2) macrofiber composite devices. The experimental results indicate a clear relationship between the variation in the electrical impedance signature of the transducer and power spectral density obtained with the PLB method. Therefore, the PLB can be a simple and effective method for assessing the sensitivity of transducers for damage detection in SHM systems based on the EMI technique.