Adrian Cuc

Abstract: In this paper we review the state of the art in an emerging new technology: embedded ultrasonic non-destructive evaluation (NDE). Embedded ultrasonic NDE permits active structural health monitoring, i.e. the on-demand interrogation of the structure to determine its current state of structural health. The enabling element of embedded ultrasonic NDE is the piezoelectric wafer active sensor (PWAS). We begin by reviewing the guided wave theory in plate, tube, and shell structures, with special attention to Lamb waves. The mechanisms of Lamb wave excitation and detection with embeddable PWAS transducers is presented. It is shown analytically and verified experimentally that Lamb wave mode tuning can be achieved by the judicious combination of PWAS dimensions, frequency value, and Lamb mode characteristics. Subsequently, we address in turn the use of pitch-catch, pulse-echo, and phased array ultrasonic methods for Lambwave damage detection. In each case, the conventional ultrasonic NDE results are contrasted with embedded NDE results. Detection of cracks, disbonds, delaminations, and diffuse damage in metallic and composite structures are exemplified. Other techniques, such as the time reversal method and the migration technique, are also presented. The paper ends with conclusions and suggestions for further work.

TL;DR: In this article, the results obtained using guided Lamb waves to detect flaws in aluminum specimens with design features applicable to space applications were presented. And the results have demonstrated the ability of piezoelectric wafer active sensors working in conjunction with guided Lamb wave to detect various types of damages present in complex geometry structures typical of space applications.

TL;DR: In this paper, the interaction between piezoelectric wafer active sensors (PWAS) and structural waves and vibration is addressed, and the use of the transfer matrix method is used to model the electromechanical impedance method for direct reading of high-frequency local structural vibration and comparison with FEM results.

TL;DR: In this article, the authors present and discuss the challenges and opportunities related to the use of PWAS in the structures specific to space applications, where the challenges posed by space structures are often different from those encountered in conventional structures.

TL;DR: In this article, a study of the use of guided Lamb waves for disbond detection in adhesively bonded layered media using piezoelectric wafer active sensors (PWAS) is presented.