円孔を有するCFRP平板における疲労損傷過程の同期超音波測定による評価

概要

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Ultrasonic measurement was carried out in synchrony with the fatigue cycle in the fatigue testing of a CFRP plate with a circular hole. With increasing number of cycles, the reflection intensity from the specimen bottom was monotonically decreased, and the decreasing rate of this reflection at a position oblique to the circle became larger than that at a position lateral to the circle. Also, as the number of cycles increased, multiple reflections were observed in the mapping of the ultrasonic wave. At the depth these reflections were observable, delamination was seen on the cross section of the specimen. The mapping at the maximum stress state was subtracted from that at the minimum stress state to obtain the subtracted mapping, in which positive and negative changes in the ultrasonic wave were recognized. The positive change seemed to correspond to delamination and the negative change to crack, such as the transverse crack.
一般社団法人日本非破壊検査協会の論文