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Prof. Sohichi Hirose

Numerical wave analysis for advanced nondestructive ultrasonic testing


Sohichi HIROSE

Tokyo Institute of Technology, Japan


Ultrasonic testing is an important nondestructive method for flaw detection and evaluation of materials and structures. However, ultrasonic waves sometimes show unexpected behaviors due to complicated material properties and geometries of test objects. Numerical analysis of ultrasonic waves plays an important role in interpreting unexpected wave phenomena. Nowadays, thanks to the development of computer technology, it is easy to access computer resources for the analysis of ultrasonic waves. In addition to interpretation of wave phenomena, numerical wave analysis has more applications in nondestructive ultrasonic testing. For example, numerical analysis can be utilized for signal processing of ultrasonic waveforms, optimal design of measurement system, and an alternative tool to experiment for POD evaluation. In this lecture, two applications of numerical analyses are introduced to develop advanced ultrasonic testing. One is numerical simulation of nonlinear ultrasonic testing, in which higher harmonic and sub-harmonic generation due to crack contact is investigated in detail by means of a time-domain boundary element method. Another topic is the utilization of a numerical method in SAFT (Synthetic Aperture Focusing Technique) imaging. The ultrasonic beam radiation in an object is calculated by an approximate wave solution, and the artifacts in flaw images are eliminated by taking account of the calculated beam radiation in the SAFT processing of phased array data.