Session: Ultrasonic Arrays I

Paper Number: 170237

170237 - Reverse Time Migration for Body Wave Imaging in Metals 

Abstract: 

While traditional imaging techniques such as the Total Focusing Method (TFM) are widely used, they often exhibit limitations in resolving fine structural details and accurately delineating defect boundaries—particularly in complex or attenuative materials. This study presents an adjoint-based reverse time migration (ARTM) methodology, grounded in adjoint tomography theory, as an advanced full-wavefield imaging approach for defect characterization in metallic and composite plates. The proposed ARTM technique utilizes complete time-domain wavefield data and incorporates elastic material properties to generate high-resolution images of subsurface features. Several imaging conditions are formulated based on physically meaningful elastic parameters, including compressional and shear wave velocities, density, and acoustic impedance. Experiments are conducted on both metal and composite plate specimens with embedded artificial defects. For each specimen, parameter-specific ARTM images are reconstructed and benchmarked against conventional TFM results. Evaluation metrics focus on defect localization accuracy, boundary definition, and artifact suppression. The ARTM approach demonstrates superior performance, particularly in resolving complex defect geometries and minimizing false positives near material heterogeneities. In composite materials, the method further benefits from enhanced mode separation and contrast improvement, addressing challenges posed by anisotropy and multiple scattering. Overall, this work highlights the advantages of adjoint-based RTM for ultrasonic NDE, offering a physics-consistent and high-fidelity imaging alternative for structural health assessment in critical engineering components.

Presenting Author: Jiaze He Harbin Institute of Technology

Presenting Author Biography: Dr. Jiaze He is a tenured professor in the Department of Astronautical Science and Mechanics at Harbin Institute of Technology (HIT). Previously, he served as an assistant professor in the Department of Aerospace Engineering and Mechanics at the University of Alabama, a postdoctoral research associate in the Theoretical & Computational Seismology group at Princeton University, a research scholar at the National Institute of Aerospace, and an adjunct assistant professor in MAE at NCSU. He has been the PI for a key NSFC project and four NSF/NASA projects, etc. He is a committee member of the ASME Nondestructive Evaluation, Diagnosis & Prognosis Division (NDPD) Executive Committee, the Committee on Health Monitoring as well as the Committee on Composite Material Testing and Evaluation Technology for the Chinese Society for Composite Materials, and the SAE AMS K Non-Destructive Methods and Processes Committee. In 2023 and 2024, he chairs the Congress-Wide Symposium on NDE & SHM at ASME IMECE. He has also been a topic organizer, session chair, and student competition organizer at international conferences such as SPIE Smart Structures & NDE, QNDE, ASME IMECE, SMSS, and SMN. Additionally, he has reviewed grants for the Chinese Ministry of Industry and Information Technology, NASA, and the U.S. Department of Energy’s Office of Nuclear Energy. He has also acted as a peer reviewer for 25 international journals, as well as a book reviewer for Wiley Publishing in the areas of structural health monitoring and artificial intelligence.

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