Validation of R6 using finite-element analyses of cracked cylinders under thermal loading

摘要

This paper presents validation of the treatment of secondary stresses within Revision 4 of the R6 assessment procedure using finite-element (FE) analyses of cracked cylinders under thermal loading. A cylinder with a fully-circumferential internal crack and a part-circumferential external surface crack are considered as model examples. The crack driving force values obtained from cracked-body FE analyses are compared to values obtained using simplified uncracked-body routes within R6. The secondary stress is applied using a temperature gradient. Various temperature loadings and crack sizes have been examined. Also, work performed by the Central Research Institute of Electric Power Industry (CRIEPI) in Japan, which has examined the same geometries, has been compared to the present FE results in some instances. It is concluded that for the cylinder with a fully-circumferential internal crack the R6 routes are conservative when the thermal load is applied as an axially linear or radially non-linear temperature distribution. The R6 routes are generally conservative when the thermal load is applied as a radially linear temperature distribution, and is only very slightly unconservative in some of the cases. Good agreement is obtained between the present work and the CRIEPI data.