Experimental and analytical studies of leak-before-break on circumferentially through-wall cracked pipes under bending load : Part-1 (September 1993 - June 1994)

摘要

Fracture control of structures is the concerted efforts by designers, metallurgists, production and maintenance engineers and inspectors to ensure safe operation without catastrophic fracture failures. If fracture is to be prevented, the strength should not drop below a certain safe value which means that cracks must be prevented to reach a critical size. Since piping is very important component in nuclear power plants, fracture control plans have been employed increasingly to ensure for better plant availability. Leak-before break (LBB) is now widely applied in nuclear industries as a means of assessing the susceptibility of a pressurised components to failure by unstable crack growth. In this report experimental and analytical studies are conducted on circumferential through wall cracked pipe subjected to pure bending load. Pipes made of three different types of steels are tested with crack size varying from 15% to 50% of circumference. Experimental results pertaining to fracture load, crack mouth opening displacement (CMOD), load point rotation and J-integral are presented. Prediction of maximum moment and stress based on net-section collapse (NSC) method and modified NSC method are also presented and compared with experimental data. Comparison between experimental and analytical results were found to be good. These all studies throw some more light on the understanding of the pipe fracture and relative accuracy and margin of conservatism of the methods when applied to full scale set up. (author). 32 refs., 45 figs., 12 tabs., 2 appendixes. (Atomindex citation 26:044978)