| Due to the excellent connection performance of the welded structure and the simple manufacturing process,it is widely used in the engineering field.After longterm service,the weld portion of the welded structure,especially the weld toe and the root of the weld,often suffer from fatigue failure due to stress concentration.In view of the current high welding quality of major equipment steel structures,the current research focuses on the early behavior of short toe cracks.In this paper,the crosswelded joints are taken as the research object,and the early behavior of short cracks is considered.Based on the extended finite element method(XFEM),the simulation study on short crack initiation and propagation of welded structures is carried out.main tasks as follows:(1)Based on the XFEM technology,the crack initiation position of the welded structure and its influencing factors were studied.The weld seam geometry,weld toe chamfer and material properties were established.The finite element model of the weld toe chamfer is set and two material properties are set respectively.The influence of the above parameters on the crack initiation position of the welded structure is analyzed.(2)Based on XFEM technology,the strain distribution near the crack and the stress intensity factor at the crack tip are calculated.The effects of initial short crack length and angle on the crack propagation path are studied by combining different initial short crack insertion directions.Regularity;a fatigue life model considering short crack behavior is used to analyze the proportion of short crack stages to the overall fatigue life of the welded structure.(3)Considering the microstructure characteristics of the material,the geometric model of the grain is established based on the Thiessen polygon method,and the mechanical properties of the grain boundary and the slip zone are simulated by the cohesive force model,which realizes the short grain size.Simulation of crack propagation. |
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