Numerical Analysis of Elastic Wave Propagation on Simulation of Ultrasonic Examination
I. Komura, H. Nakamura, Y. Ikegami, Toshiba Corp., Yokohama, Japan; S. Nakada, M. Igeta, Japan Power Engineering & Inspection Corp. , Yokohama, Japan
ABSTRACT
Improvement of ultrasonic examination capability in austenitic stainless steel weldment is one of the important problems for ensuring the integrity of component in nuclear industry. Much efforts have been devoted in order to overcome the difficulty of defect detection and sizing capability of ultrasonic examination in such materials. Reason of such difficulty occurs due to elastic anisotropy and elongated crystals in the direction of cooling gradient which are imposed during solidification. Ultrasonic beam is skewed in such materials, and many structural noises and attenuation are observed in quite different from isotropic materials. This will lead to the problems in detecting, locating and sizing of a defect. In order to address these problems, development of a computer. Simulation system has been started. Computer simulation which is based on the numerical analysis has the benefit such as better understanding of the wave propagation process in the weldment, and as a tool for parameter studies for understanding the influence of the probe parameters, defect characteristics, and examination method on the test results. For the first phase of this program, high speed analysis program by ray tracing method and finite element program for detailed analysis are developed in two dimensional isotropic materials. As a result of simulation to the model which contains side drill hole and planer defect, wave propagation process such as mode conversion around the defect is well coincide in both methods. Furthermore, it is shown that the mesh size in finite element method affects to the results especially in the case of beam transmission through the interface of different materials, and that fine mesh related to the ultrasonic wave length is required for obtaining the accurate received ultrasonic wave.
Publication Source: First International Conference on NDE in Relation to Structural Integrity for Nuclear and Pressurised Components , 20 - 22 October 1998, Amsterdam, Netherlands. Held by the Joint Research Centre of the European Commission. Publisher:Woodhead Publishing Limited
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