Ultrasonic array imaging of highly attenuative materials with spatio-temporal singular value decomposition.

Area of Science:

• Materials Science
• Non-Destructive Testing
• Ultrasonic Imaging

Background:

• High-density polyethylene (HDPE) pipes are crucial in the nuclear industry, demanding rigorous structural integrity assessments.
• Ultrasonic array imaging is vital for HDPE pipe inspection, but signal attenuation and noise reduce image quality.
• Viscoelastic attenuation in HDPE significantly degrades signal levels, leading to low signal-to-noise ratios.

Purpose of the Study:

• To propose a novel processing algorithm for enhancing ultrasonic array image quality in HDPE pipes.
• To address the challenges of low signal-to-noise ratios caused by viscoelastic attenuation in HDPE materials.
• To improve the detection and characterization of defects in HDPE pipes using advanced imaging techniques.

Main Methods:

• A domain-adapted spatio-temporal singular value decomposition (STSVD) algorithm was developed.
• Radio frequency (RF) data were demodulated into complex analytic signals (in-phase and quadrature - I/Q components).
• STSVD processed the I/Q data, which was then converted back to RF signals for Total Focusing Method (TFM) imaging.

Main Results:

• The proposed STSVD combined with TFM effectively filtered noise and improved signal quality.
• High-quality ultrasonic images were generated for HDPE pipe materials.
• The method demonstrated successful detection and characterization of artificial defects, including deeper ones.

Conclusions:

• The developed domain-adapted STSVD processing algorithm significantly enhances ultrasonic array imaging for HDPE pipes.
• This method provides a robust solution for inspecting highly attenuative materials, crucial for nuclear industry safety.
• The technique offers improved defect characterization, especially for defects located deeper within the material.