Effect Of Welded Mechanical Heterogeneity On Mechanical Field At Crack Tip

Welded joints are easy to exist crack-like defects, and it also is more dangerous to occurfracture and break than other location of the structure, which would cause the failure of wholewelded structure in this dissertation. Furthermore, the heterogeneity of material andmechanical properties in welded joints might change the failure modes of welded structures.Main research has performed in this study are as follows.(1) The yield strength and other mechanical parameters across the welded joints werecalculated based on the microscopic hardness. And the continuous changes of the mechanicalproperties across the welded joints was innovatively achieved in the finite element analysis byusing the predefined field function in ABAQUS, which effectively reduce the calculatederrors induced by the sudden change of the material mechanical property in the conventionalmodeling of welded joints.(2) The finite element models of pipe specimen and tensile plate specimen of the weldedjoints were built, which are containing semi-elliptical surface cracks at three differentlocations of welded joint. And the mechanical field at the crack tip in each specimen wasnumerically simulated and analyzed by ABAQUS. Then the influence rule of mechanicalheterogeneity on the mechanics field at the crack tip was obtained by comparing variousfracture mechanics parameters and the stress and strain fields at the crack tip of eachspecimen.Research approach and results achieved in this study provide a theoretical basis and atechnical means for further study on the effect of the material mechanical heterogeneity ofwelded joints on the mechanics field at the crack tip and the safety analysis of the weldedstructure.