At the invitation of Ultrasonic Physics and Testing Lab, Prof. Masumi Saka from Tohoku University and Prof. Yang Ju from Nagoya University visited IACAS and gave lectures on Mar. 23. Prof. Masumi Saka was an international well-known scholar in non-destructive field. Now he is the director of Japanese Society for Non-destructive Testing. Prof. Yang Ju graduated form Tsinghua University and got his doctor degree in Tohoku University. The seminar was chaired by Lin Weijun and Prof. Shen Jianzhong made brief introduction of the two speakers.　  

Prof. Masumi Saka gave a lecture titled "Thermal Opening Technique for Nondestructive Evaluation of Closed Cracks". He said there was powerful scattering stress in closed cracks, which set obstacles for testing by ultrasonic waves. The thermal opening technique can lessoned the influence of scattering stress and strengthen the extent of dispersion wave, which made it easier to find the closed cracks. In addition, through the signal travel time differences between weld corner echo wave and scattering wave, the depth of cracks could be easily measured. At present, it was proved that thermal opening technique was an advanced and innovative method in nondestructive evaluation of closed cracks. 　　 　　

The title of Prof. Yang Ju's report was "Microwave Nondestructive Testing". He said the traditional non-destructive testing method was generally used in the materials of different density. If the density was the same, the traditional way was not effective. The microwave testing method mainly depended on the electronic features of the material. In the past several year, Prof. Yang Ju and his group made lots of efforts in researching the theory, practice and application of microwave testing method. At present, this method is widely used in the testing of fatigue crack, integrated circuit, semiconductor materials and the thinning testing of pipes.

A deep discussion on the mentioned methods was followed between the audience and the speakers. After that, the two professors looked around the campus of the institute.

Prof. Masumi Saka  

Prof. Yang Ju