ポンピング波によるき裂開閉口を利用した非線形超音波非破壊検査

概要

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Nonlinear ultrasonic nondestructive evaluation is highly attractive as a technique for detecting and evaluating closed cracks in material. Usually an ultrasonic wave of MHz order is used in this technique to precisely evaluate the size of the cracks. This study describes a nonlinear ultrasonic technique that uses a low frequency range to inspect an entire region of material roughly and quickly. The pumping wave generated by a giant magnetostrictive actuator, ranging about a few kHz, bends a test piece, and opens and closes fatigue cracks within it. At the same time, an ultrasonic wave of about 100kHz was emitted in the material. Sideband peaks were then clearly obtained in defective materials by changing resonant frequencies of the material at the repetition rate of the crack opening and closing. This paper also reports that spatial distributions of the sideband peaks clearly indicated the existence of a fatigue crack in a material.
一般社団法人日本非破壊検査協会の論文