水浸斜角超音波法による微小表面き裂の内部形状測定 : 第1報, 後方反射強度とき裂深さ・傾きの関係(<小特集>実験計測技術の新展開)

概要

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Fatigue life of mechanical structures have been estimated according to Safety Life Design. In this study an ultrasonic technique for quantitative nondestructive evaluation of small surface fatigue crack is developed. The use of an oblique longitudinal wave with large angle (over the critical angle) of incidence upon specimen surface is emphasized. Ultrasonic testing was performed with small surface fatigue cracks and artificial defects. To evaluate cracks, maximum amplitude of reflection echo due to these defects were used here. From such measurements, we show that by using this parameter, above 115 μm surface length of fatigue surface crack can be detected. Depth and deflection of these cracks also can be detected. From these results we deduced an experimental equation to calculate length and depth of crack. Finally, a model based on three dimensional elastodynamics was proposed to simulate this ultrasonic technique, and numerical analysis were done for surface crack reflection problem.
一般社団法人日本機械学会の論文
2001-03-25