非線形超音波（高調波）法による材料劣化・損傷の非破壊評価

抄録

Using the immersion local resonance ultrasonic technique, we have detected and imaged electron radiation damage of pressure vessel steel A533B, artificial small defects in a combustion nozzle of the rocket engine for repeatable use and weak adhesive area in bonded CRPP plates. In the local resonance ultrasonic technique, long sine-burst waves of through-thickness resonance frequency excite through-thickness resonance only within a focused beam area. When the plate thickness is constant, the resonant amplitude changes due to the variation of material properties. The resonant amplitude of the irradiated A533B steel sample is greater than that of unirradiated one. Artificial small defects, EDM slits, introduced in the combustion nozzle mockup of the rocket engine are clearly imaged. The weak adhesive area in bonded CRPP plates is also delineate. The local resonance ultrasonic technique is useful for detecting and imaging the variation of material properties, which are not performed by the conventional ultrasonic method.