Multi-Location Actuators and Piezoceramic Based 2-D Spiral Array for Structural Health Monitoring: Thin Isotropic Panels

In this paper, a new and robust 2-D phased array technique with multiple distributed actuators is studied for damage detection application based on Guided Lamb Wave (GLW) interrogation in a thin isotropic panel. A 2-D phased array technique using a single actuator located near the center of the 2-D phased array is unable to detect a linear crack oriented normal to the wavefront of the GLW excited from the actuator. To overcome this limitation, the 2-D phased array is coupled with multiple actuators in this study where the actuators are positioned at various locations on a test panel while the 2-D phased array is mounted at the center of the panel. A piezoceramic based 2-D phased array with a spiral configuration is used as a sensor array and the corresponding 2-D phased array signal processing is used to produce array responses and detect various damages. An innovative GLW propagation and reflection analysis technique is implemented to evaluate the damage locations in the panel. Experimental results demonstrate that the 2-D phased array damage detection technique using multiple distributed actuators can provide more robust damage detection scheme in thin isotropic panels than a technique with a single actuator element.