Temporal enhanced Ultrasound: A new method for detection of porosity defects in composites

Abstract

Non-Destructive Evaluation (NDE) methods are commonly employed for identifying porosity, which is one of the most common manufacturing defects observed in composite structures. Among current widely used approaches are conventional ultrasonic methods such as pulse-echo analysis based on loss of signal amplitude. Application of these conventional ultrasonic methods, however, can be challenging in cases where the loss of signal is negligible, such as with porosity. In this paper, we propose Temporal-enhanced Ultrasound (TeUS) as a novel ultrasound-based imaging technique for NDE of composites. TeUS represents the analysis of a sequence of ultrasound images obtained from composites by varying an image acquisition parameter, such as the focal point, over the sequence. We present details on the analytical formulation of TeUS, followed by extensive simulation and experimental results to demonstrate the efficacy of TeUS for porosity detection, compared to a conventional ultrasound-based porosity detection method. The results indicate that TeUS has excellent sensitivity for identifying subtle changes in the level of porosity within composite samples, with the possibility to reduce the need for reference samples.