Analysis Of Mechanical Field At Cracking Tip In Welded Joint Based On XFEM

Dissimilar metal welded joint in the safe end of nuclear power plant is susceptible to welding process coupled with material microstructure.geometric discontinuity and mechanical heterogeneity,which made the crack propagation behavior more uncertainty and regularity at weld region.To provide some help for the safety evaluation of DMW joints,DMW joints is regarded as the research object,which adopted the extended finite element method(XFEM)module in ABAQUS,according to structural material mechanical property,loading condition and cracked initial location and propagation behavior under given crack fracture criterion,crack propagation path and distribution of mechanical field at crack tip were analyzed.The main works in this dissertation are as follows:(I)Based on XFEM module in finite element software ABAQUS.the crack propagation finite element model of DMW joints under elastic-plastic condition was established,which realized the crack propagation of four homogeneous materials model and DMW joints material model,proposed a research method of crack propagation based on XFEM and elastic-plastic fracture mechanics;(2)Thc four homogeneous materials model of DMW joints were established,the distribution of mechanical field at crack tip and characteristics of crack propagation path in crack propagation processing were analyzed.The influence of tensile strength,clastic modulus and yield strength on the mechanical field at crack tip and crack propagation path were obtained,which provide a reference standard for crack growth behavior.(3)Thc crack propagation finite clement model of DMW joints were established,the distribution of mechanical field at crack tip and characteristics of crack propagation path in low carbon steel A508 and 316L stainless steel were analyzed.The influence of tensile strength,elastic modulus and yield strength mismatch on the mechanical field at crack tip and crack propagation path were obtained.In this dissertation,the DMW joints crack propagation based on XFEM analysis method for safety assessment of nuclear power plant DMW joints will have great significance.