1315 Monitoring of Crack Development Based on Nonlinear Piezoelectric Impedance Modulation
Details
In this paper, a novel monitoring methodology to detect and characterize damages accompanied by changes in the micro/macroscopic condition of surface contact is proposed. The presented system consists of a PZT patch attached on the structural surface excited by a high frequency harmonic wave. When the structure is subjected to the operational or ambient load at low frequencies, it vibrates, and the inherent damages may introduce a nonlinear effect to the vibro-acoustic dynamics that induces an interaction between the low frequency structural vibration and the high frequency transmitted wave. This nonlinearity is observed as the modulation of the electric impedance of the PZT patch synchronous with the structural vibration. By investigating the relationship between the modulations and the structural vibration, the nonlinear characteristics of the damages can be specified. Experiments using a beam with low-cycle fatigue cracks are conducted for illustrative purpose.
