Study of distributed piezoelectric sensors for modal sensing of a cantilever beam

With conventional discrete point sensors, there are several tradeoffs and concerns in structural measurement and structural control. In post-processing, spatial aliasing is one of the possibilities for inaccurately reconstructing structural responses; in structural control strategies, the spillover effect has been one of the most significant challenges. Theoretically, these concerns can be eliminated by utilizing spatially distributed sensors. In addition, distributed sensors can be implemented for in-situ measurement, which can provide improved and thorough monitoring of aerospace structures in flight. The distributed sensors made of smart materials such as piezoelectric materials have the capacity to improve aerospace structural safety. One of the most widely studied smart materials for distributed sensors is polyvinylidene fluoride (PVDF). Due to its low stiffness and high flexibility to be combined with various structures without affecting the properties of host structures, PVDF has the potential to be economically implemented in structural sensing. Since the 1990s, after Lee and Moon’s innovative design of piezoelectric modal sensors, the interest in PVDF modal sensor has increased. Lee and Moon’s design is based on shaping the sensor’s width to be proportional to the “curvature eigenfunction.” [12]. By utilizing the orthogonality between eigenfunctions, the sensors can be only sensitive to the selected modes. In this work, the characteristics and applications of the PVDF bonded to the Euler-Bernoulli beam are first discussed. The sensitivity analysis of Lee and Moon’s design is performed numerically, and a concept of the piezoelectric film sensors based on rectangular segments is proposed. The experiment to validate the performance of rectangular-shaped piezoelectric modal sensors is also conducted