Simulation Of Ductile Fracture In Dissimilar Metal Welded Joint Based On XFEM

The safe-end dissimilar metal welded joints in primary water system of pressurizedwater reactor (PWR) in nuclear power plant are weak structures in nuclear powerequipment due to they are prone to ductile damage and fracture in the service process. Theductile fracture behavior in dissimilar metal welded joint is complicated, which is affectedby mechanics, materials and environment. In this thesis, the ductile fracture process ofwelded joint is analyzed by using the extended finite element method (XFEM). The mainworks completed are as follows:(1) The ductile fracture simulation method of XFEM is analyzed, the effects ofmaximum principal stress, critical energy release rate in fracture criterion and elasticmodulus, yield stress, hardening exponent in material model on the load-bearing capacity,fracture resistance, stress and strain at the crack tip, crack growth path of the model arestudied;(2) The fracture process of single-edge notch with different locations in the weldedjoint under pure tensile loading is analyzed, the influences of different location of crack,such as homogeneous materials, the center of weld metal, interface and sub-interface on thestress and strain field at the crack tip, crack propagation behavior, carrying capacity andfracture resistance of the model are researched;(3) The failure process of inclined crack in the center of the welded joint is analyzed,the variation of stress and strain at the crack tip, the direction and distance of the crackpropagation, carrying capacity and fracture properties of the specimen when the crack withdifferent inclined angle and different locations, such as homogeneous materials, the centerposition of welding seam and different materials are discussed;(4) The crack propagation of single-edge notch with different locations in the weldedjoint under mixed-mode loading is analyzed, the effect of tangential load on the ductile fracture process is analyzed, and then the change of the stress-strain distributions in front ofthe crack tip, crack growth path, load-bearing capacity and fracture resistance in horizontaland vertical directions of the specimen when the crack is located at homogeneous materials,the center of weld metal, interface and sub-interface between different materials areinvestigated.