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Updated: Aug 5, 2026
05:30
Crack Monitoring in Resonance Fatigue Testing of Welded Specimens Using Digital Image Correlation
Published on: September 29, 2019
Nonlinear ultrasonic phased-array imaging method for closed cracks based on conjugate delay-multiply-and-sum and
Jie Xue1, Zhuoxu Liu1, Jingxun Zhou1
1School of Mechanical Engineering, Hebei University of Technology, Tianjin 300401, PR China; Key Laboratory of Advanced Intelligent Protective Equipment Technology (Hebei University of Technology), Ministry of Education, Tianjin 300401, PR China.
Ultrasonics
|July 29, 2026
Summary
This study introduces a new nonlinear ultrasonic imaging method to overcome limitations in detecting closed fatigue cracks. The advanced technique enhances imaging contrast and crack-tip localization for better material inspection.
Area of Science:
- Materials Science and Engineering
- Non-Destructive Testing (NDT)
- Ultrasonic Imaging
Background:
- Conventional linear ultrasonic phased-array imaging struggles with closed fatigue cracks due to crack closure and propagation direction.
- System nonlinearity in phased-array instruments causes residual linear artifacts in odd-even fundamental wave amplitude difference (OE-FAD) imaging.
- Stable, high-contrast imaging of closed fatigue cracks remains a significant challenge in NDT.
Purpose of the Study:
- To develop and investigate a nonlinear ultrasonic phased-array imaging method for improved visualization of closed fatigue cracks.
- To address and mitigate residual linear artifacts caused by system nonlinearity in OE-FAD imaging.
- To enhance crack-tip localization and characterization of crack propagation direction for randomly oriented closed fatigue cracks.
Main Methods:
- Implementation of a complex-valued correction-factor-enhanced odd-even fundamental wave amplitude difference (OE-FAD) nonlinear ultrasonic imaging method.
- Integration with conjugate delay-multiply-and-sum (conj-DMAS) post-processing for enhanced signal analysis.
- Utilized a conventional matrix-scanning physical focusing strategy for crack visualization and localization.
Main Results:
- The proposed nonlinear method effectively compensates for amplitude and phase mismatches in imaging responses.
- Significant suppression of residual linear artifacts induced by system nonlinearity was achieved.
- conj-DMAS post-processing concentrated nonlinear responses, improving crack-tip localization and propagation direction characterization.
Conclusions:
- The developed nonlinear ultrasonic phased-array imaging method offers a practical solution for detecting closed fatigue cracks.
- The technique successfully overcomes limitations of conventional linear methods, providing stable, high-contrast imaging.
- This approach is compatible with conventional phased-array equipment, making it readily applicable in industrial settings.
