Papers by Keyword: Plastic η Factor

Abstract: Tensile and fracture toughness tests of coolant piping materials were performed at various loading rates and temperatures. The crack measurement method for coolant piping materials consisted of the unloading compliance method for quasi-static loading conditions and condition, while the electric potential drop method and the normalization method for quasi-dynamic loading conditions. Tensile and fracture toughness tests of coolant piping materials were performed at the design temperatures of the primary piping system of nuclear power plants, which are 449K (176°C) and 589K (316°C). Also, the plastic η factor considering strength mismatch of welding part was applied to the fracture toughness test results and the J-R curves by the plastic η factor considering strength mismatch of welding part was compared with the J-R curves by the plastic η factor introduced in ASTM E1820-01.

Abstract: In this study, the plastic η -factors of the SA508Cl.1a narrow-gap welding part, which is used for the primary piping system in a nuclear power plant were obtained by using finite element analysis and the modified fracture toughness testing method was suggested for the narrow-gap welding part. Also, we have performed the fracture toughness test for the SA508Cl.1a narrow-gap welding part by applying the new testing method and then we compared the results with those from the ASTM fracture toughness test.

Abstract: Application of the leak-before-break concept to nuclear piping requires accurate fracture mechanics assessment on pipes with postulated circumferential through-wall crack subject to combined tension and bending. One important element is determination of relevant J-resistance curve for pipes under combined loading. This paper provides experimental J estimation method for the circumferential through-wall cracked pipe under combined tension and bending, based on the load-crack opening displacement (COD) record to estimate J-resistance curve. To give confidence in the proposed method, the J results from detailed elastic-plastic finite element (FE) analysis are also compared with estimated J based not only on proposed method but also on conventional method using load-load line displacement, which shows that estimated J based on the proposed method provides reliable J estimates regardless of analysis condition, on the other hand, the conventional method using the load-load line displacement record gives erroneous results for shallow cracks.

Abstract: This paper compiles solutions of plastic η factors for standard and non-standard fracture toughness testing specimens, via detailed three-dimensional (3-D) finite element (FE) analyses. Fracture toughness testing specimens include a middle cracked tension (M(T)) specimen, SE(B), single-edge cracked bar in tension (SE(T)) and C(T) specimen. The ligament-to-thickness ratio of the specimen is systematically varied. It is found that the use of the CMOD overall provides more robust experimental estimation than that of the LLD, for all cases considered in the present work. Moreover, the estimation based on the load- CMOD record is shown to be insensitive to the specimen thickness, and thus can be used for testing a specimen with any thickness.