Simulation Of Plastic Zone Near The Crack Tip In A Weld Joint And Multiple Cracks Fracture

Welding has become an essential method of molding modern industrial equipments. However, as weldments in the manufacturing process or service, a different number of cracks or defects would come out of weld joints in different positions, so a reasonable integrity assessment of the welded structure would be needed to protect life and property safety. The mismatch factors of weld joint affecting on the fracture mechanic parameters, plays an important role in integrity assessment for welded structure. In this paper, degree of strength mismatch M and slenderness of weld w affecting on plastic zone size are studied. Finite element models with different M andΨunder various loads were established, and the variations of plastic zone size were obtained.The load-distance curves of double-cracked plate specimen with different distances between adjacent cracks were simulated by using GTN damage model, which is embedded in ABAQUS, and the material parameters are from the steam turbine rotor steel 30Cr2Ni4MoV. According to the load-distance curves, the maximum loads and coalescence loads were obtained, and the effects of different distance on them were found. Compared to combine rules, the bias were given. The load-distance curves of crack plates with weld joint were also calculated, and the results showed the changes of loads with variation of crack locations.