Session: Advanced Modelling for NDE

Paper Number: 170791

170791 - Advanced Signal Processing for Air-Coupled Ultrasound Structural Inspection Using Matched Filtering Techniques 

Abstract: 

In the context of Non-Destructive Testing (NDT), non-contact inspection methods are increasingly essential for evaluating modern composite structures where traditional ultrasonic testing techniques fall short.

Air-coupled ultrasound testing (ACUT) offers a promising solution, enabling the inspection of materials like CFRP, GFRP, and honeycomb cores. Indeed, this technique does not require any liquid coupling or direct contact with the specimen and provides a good solution for parts that cannot be immersed due to their shape, or sensitivity to corrosion.

 Despite its advantages, ACUT can face significant challenges, partly due to poor acoustic transmission across air-material interfaces and high attenuation within the materials themselves, often resulting in low signal-to-noise ratios (SNR). To address this, advanced signal processing approaches such as matched filtering have gained attention. By transmitting coded or long-duration signals and applying correlation-based filtering on the received data, these methods can significantly enhance detectability and resolution.

In this work, we present a comparative study evaluating the advantages of matched filtering for the ultrasonic inspection of honeycomb structures, with a focus on improvements in SNR and overall signal quality. Initially, we implemented a conventional matched filter based on a reference signal acquired in the air. This approach is then contrasted with an advanced matched filter design that is directly estimated from the received RF data, enabling a more adaptive enhancement of the signal. The inspections are carried out using TPAC's multichannel Pilot+ system, which integrates an arbitrary waveform generator (AWG).

Presenting Author: Ralph ABI RIZK TPAC

Presenting Author Biography: Have a PhD in Image and Signal processing.
Currently working at the TPAc company as a Research Engineer in Ultrasound Imaging for Non-Destructive Testing

Authors:

Ralph ABI RIZK TPAC
Hector Calas TPAC
Ewen Carcreff TPAC
Gavin Dao AOS