J Estimation of Circumferential Through-wall Intrados Center Cracked Elbows under In-plane Bending

AbstractThis paper provides a J estimation of intrados circumferential through-wall center cracked elbow under in-plane bending. To find the finite element (FE) J-integral, non-linear three-dimensional finite element analyses are performed. The material properties for elastic-plastic FE analysis are assumed to be a Ramberg-Osgood model. Validity of that estimation of circumferential through-wall cracked elbow under given loading condition is evaluated. Next, effects of the elbow geometry and crack lengths are systematically investigated. Results are presented in the failure assessment diagram (FAD) space. The results show that FE J of circumferential through-wall center cracked elbow give more non-conservative results than reference stress based J estimation by R6. If an optimized reference moment was taken into consideration, almost all FE J values in the given range have only slight different of its elbow geometry and crack lengths