Enhancing ultrasonic time-of-flight diffraction measurement through an adaptive deconvolution method.

Area of Science:

• Non-destructive testing
• Ultrasonic testing
• Signal processing

Background:

• Ultrasonic signals require deconvolution for improved temporal resolution.
• Dispersive space-frequency distribution in time-of-flight diffraction (TOFD) signals complicates deconvolution for small, shallow defects.
• Identifying a suitable reference signal for deconvolution is a significant challenge.

Purpose of the Study:

• To develop an adaptive deconvolution method for TOFD measurements.
• To address the challenge of reference signal determination in TOFD deconvolution.
• To enhance the axial resolution and signal separation capabilities of TOFD.

Main Methods:

• Wavelet transform decomposes TOFD signals into sub-band signals.
• Adaptive selection of coherent sub-band signals using a coherence coefficient metric.
• Utilizing a lateral wave as a reference signal for Wiener filtering and spectral extrapolation.

Main Results:

• The proposed adaptive deconvolution method effectively separates overlapping TOFD signals.
• Improved axial resolution in TOFD imaging was achieved.
• Feasibility validated through TOFD measurement of a small, near-surface defect.

Conclusions:

• The adaptive deconvolution method offers a viable solution for enhancing TOFD measurements.
• The technique improves the analysis of small and shallow defects.
• This advancement contributes to more accurate non-destructive evaluation using TOFD.