Plane Wave Imaging Techniques for Immersion Testing of Components With Nonplanar Surfaces

Area of Science:

• Ultrasonic Nondestructive Testing
• Advanced Imaging Techniques
• Materials Science

Background:

• Plane wave imaging (PWI) offers high resolution and few transmissions for ultrasonic array imaging.
• Conventional PWI is limited for components with nonplanar surfaces, requiring prior knowledge of geometry for adapted transmission delays.
• Existing methods for nonplanar surfaces are complex and necessitate detailed pre-inspection information.

Purpose of the Study:

• To introduce a novel postprocessing approach for plane wave imaging (PWAPP) that eliminates the need for prior component geometry knowledge.
• To evaluate the performance of PWAPP in imaging defects within components featuring nonplanar surfaces.
• To compare PWAPP's effectiveness against conventional PWI and PWI adapted during transmission.

Main Methods:

• PWAPP utilizes conventional PWI transmission but incorporates two postprocessing stages: surface reconstruction and delay adaptation for internal imaging.
• The study employed simulated and experimental data from an immersed sample with a concave front surface and artificial defects.
• Performance was assessed using signal-to-noise ratio (SNR) and comparison with conventional PWI and transmission-adapted PWI.

Main Results:

• PWAPP and transmission-adapted PWI showed comparable results on simulated data, outperforming conventional PWI.
• Experimentally, PWAPP achieved SNRs of at least 31.8 dB, significantly higher than conventional PWI's 20.5 dB.
• PWAPP maintained high SNR performance even with reduced transmissions (down to a quarter of array elements) and detected all scatterers in a complex specimen.

Conclusions:

• PWAPP is a robust ultrasonic imaging technique for nonplanar components, offering high resolution and SNR without requiring pre-acquired geometric data.
• The postprocessing adaptation in PWAPP significantly enhances defect detection capabilities compared to conventional PWI.
• PWAPP demonstrates potential for efficient and effective nondestructive testing of complex geometries, comparable to the Total Focusing Method.