Nondestructive Evaluation of Cooperative Structures (NDECS)

Abstract

SHM is born from the conjunction of several techniques and has common basis with NDE. In fact, several NDE techniques can be converted into SHM techniques by integrating the sensors and the actuators inside the monitored structure. NDE is mature, since several decades of research and development have been made. Contrariwise, SHM just begins to come out from laboratories, and applications at a wide scale remain a long-term objective. In these conditions, we may wander if an intermediate way, less performing but feasible at a shorter term, would not be an attractive and relevant position.This third way consists in only embedding at well-chosen locations into the structure the stimulation (actuators or emitters) and leaving the detection (receivers or sensors) outside. To optimize such a system, Lamb waves could be used for the emission and full-field real time imaging techniques used for the reception. So, using the more recent and promising techniques of both domains -SHM and NDE -, the proposed technique could be applied at a short term, with existing technologies and would permit time and money saving for maintenance operations. A well-suited appellation for this type of technique could be: Non-Destructive Evaluation of Cooperative Structures (NDECS).The principle and first validation experiments of two possible NDECS systems, stroboscopic shearography and lock-in ultrasonic vibrothermography, imaging Lamb waves generated by embedded piezoelectric patches, are presented.