Evaluation of aseismatic integrity in HTTR core-bottom structure. 6. Dynamic strength of graphite component under stress concentration condition

In order to clarify the dynamic strength characteristics of a graphite component under stress concentration condition, the static and dynamic fracture tests were performed using scale-model specimens of the component. The strain rate applied to the specimens was around 10^-5 l/s in the static test and 1 to 5 l/s in the dynamic test. As a result of the experiment, it was found that the ratio of the dynamic strength to the static one depends on the stress gradient in the specimen; the specimen with higher stress gradient shows a higher value of the strength. Moreover, it was also found that there is a critical stress gradient at which the strength ratio reaches almost a constant value even if the stress gradient increases in the specimens. (author)