Affiliation:
1. China Special Equipment Inspection and Research Institute, Beijing 100029, China
2. Key Laboratory of Advanced Manufacturing Technology, North University of China, Taiyuan 030051, China
3. Shanghai Acoustic Laboratory, Chinese Academy of Sciences, Shanghai 201815, China
Abstract
In this work, a two-parameter inversion problem is analyzed, related to surface crack widths for measuring depths of normal surface notches, based on a laser-based ultrasonic measurement method in the time domain. In determining the depth measurement formulas, the main technique is the time delay between reflected and scattered waves. Scattered waves are generated by two reflections along the bottom and three mode transformations at the surface of the crack tips. Moreover, the scattering angle of the mode-conversion waves is 30°. These two key factors lead to corrected item “2wβ” in the depth measurement formula. A laser-based ultrasonic experimental platform is built to generate and receive surface waves in a non-contact manner on aluminum and steel specimens with surface cracks. The depth measurement method proposed in this paper has been validated through theoretical, simulation, and experimental methods. Finally, in this paper, an effective approach for quantitatively measuring crack depths, based on laser ultrasound, using the time-domain properties of surface wave propagation is provided.
Funder
National Natural Science Foundation of China as National Major Scientific Instruments Development Project
General Project of Basic Research Program in Shanxi Province
The Opening Fund for Key Research Bases of Nanchang Hangkong University
The Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi
The Opening Project of Key Laboratory of Biomedical Imaging and Image Data of Shanxi Province
The Opening Project of Shanxi Key Laboratory of Advanced Manufacturing Technology
The National Natural Science Foundation of China