Experimental and numerical validation of guided wave phased arrays integrated within standard data acquisition systems for structural health monitoring

Phased array methods are a promising approach to damage detection by enabling guided wave steering and beam focusing leading to improved localization and sizing of structural damage. Due to the costs and challenges to addressing piezoelectric arrays in parallel, most phased array methods actuate piezoelectric elements one at a time in round-robin fashion with postprocessing algorithms used to synthetically steer and focus the guided waves. In this study, true parallel excitation and sensing of ceramic piezoelectric actuators is implemented in a standard structural health monitoring data acquisition system without requiring highly specialized and expensive ultrasonic data acquisition equipment. The study performs both numerical simulation and laboratory experiments to illustrate the damage detection capabilities of a piezoelectric phased array. Laboratory experiments are first performed using the high-speed data acquisition system to actuate and sense piezoelectric elements bonded in a linear array on an aluminum plate. To visualize the direction and focal point of the guided waves, a laser Doppler vibrometer triggered by the data acquisition system is adopted to scan the surface displacements of the plate. The study verifies that the location and size of damage can be accurately detected in the plate using the phased array operated by the structural health monitoring data acquisition system. To explore the capabilities of the system to detect different damage cases, the computationally efficient local interaction simulation approach is implemented on a graphic processing unit to simulate the performance of a linear phased array to steer and focus Lamb waves for damage detection.