| A new structural health monitoring (SHM) system, which consists of a piezoelectric drive and a ferroelectric-based sensor unit, is proposed. Unlike the current SHM system, the proposed SHM system has only a sensor unit and a drive unit, a low-power source to operate the system, and requires no heavy weight memory unit to record data.;For the ferroelectric-film-based sensor unit, a polarization fatigue measurement system is developed and a numerous sets of polarization fatigue tests on ferroelectric films with millions of repetitions are conducted. The polarization fatigue data of the ferroelectric thin films provide the reduction of their polarization under a certain number of cyclic electric fields. For the drive unit, a bulk piezoelectric ceramic is mounted on a structural component sending out voltage, which is induced by the deformation on the structural component. By electrically connecting the drive unit to the sensor unit and an interface circuit in between, we utilize the polarization fatigue data of ferroelectric-film-based sensor unit to record only a critical number of cycles of a dynamic load history of larger magnitudes. The proposed SHM system is verified by a numerous sets of random-amplitude dynamic tests, which demonstrate that the proposed SHM system performs reliable accuracy for counting cycles, whose amplitude is larger than a specific value.;To protect the fragile piezoelectric ceramic based drive unit, we analyze the reduction of stress if the piezoelectric patch is mounted on a structural component with an adhesive layer in between. We develop a theoretical model to analyze the elastic and viscoelastic behaviors of the load transfer design statically as well as dynamically. Finite element analysis is conducted to verify the accuracy of the theoretical model. |
