Validity Examination on Evaluation of J-R Curve in the Nuclear Reactor Pressure Vessel Steels and Aluminum Alloys by Load Ratio Analysis

원자로 압력용기강 및 Al 합금재의 J-R곡선평가시 Load Ratio 해석의 유효성 검토

The purpose of this study is to evaluate the validity examination of the J-R curve characteristics for the nuclear reactor pressure vessel steels and Al alloys by the load ratio analysis. The results of the load ratio analysis are compared with those of the J-R curve which are obtained by the ASTM unloading compliance method. The crack length calculated by the load ratio analysis is agree well with the measured final crack length. The slope of the exponential J-R curve estimated by the load ratio analysis is slightly smaller than that by the ASTM unloading compliance method. The J-R curve obtained by the ASTM unloading compliance method is over-predicted and should be offsetted due to the initial negative crack. On the other hand, the load ratio analysis method can evaluate the J-R curve by only load-displacement curve without particular crack measurement equipment.