Ultrasonic Phased Array Imaging Technology for the Inspection of Aerospace Composite Structures

In this article, we present the challenges and achievements in development and use of a compact ultrasonic Phased Array (PA) module and imaging technology for autonomous nondestructive evaluation of composite aerospace structures. We analyse the state of composite components by processing full waveform (A-scan) information from PA, perform slicing and visualization of the data.We further accomplish the improvement of the axial (depth) resolution by proposing a new signal processing algorithm based on threshold improved wavelet transform (TIWT), that is able to separate overlapped echoes. This algorithm extracts a reference echo model from A-scans with no defect, and uses complex continuous wavelet transform and phase information of full waveform to estimate and localize echoes of each A-scan. The results of the proposed algorithm are validated by comparing them to the reference sample measures.