Quantitative damage image construction in plate structures using a circular PZT array and lamb waves

A circular PZT ceramic wafer array based on a process of receiver beamforming is developed for damage identification in plate structures, and a method of quantitative damage image construction is presented using Lamb wave signals received from the array. Design parameters of the circular PZT array, including diameter of the PZT array, number of PZT wafers and steering angle, are investigated. Characteristics related to magnitude of the array response, viz. the reflection coefficient and distance between the damage and the array, are also analyzed. It is demonstrated that, because of the unique configuration of the PZT array, the magnitude of the array response is independent of the direction of the damage location relevant to the array. Exact propagation path of wave propagation is adopted, and therefore the damage can be reconstructed even in the near field surrounding the PZT array. To validate the proposed method, a circular PZT array consisting of one PZT actuator and several PZT sensors is used in experiments to identify damage in an aluminum plate. By considering the attenuation of Lamb wave propagation in plate structures, quantitative image construction is implemented for damage of different severities and distances from the array.