Numerical Study of Stress Triaxiality and Fracture Driving Force for Notched Specimen with Mechanical Heterogeneity(Mechanics, Strength & Structure Design)

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The effects of welding mechanical heterogeneity on the ductile fracture parameters of notched round-bar tensile specimens were investigated numerically using a large deformation finite element method. The parameter U=∫exp (1.5F_σ) dε_p, is introduced as a driving force to ductile fracture. The stress triaxiality and the driving forcee are computed in the fully yielding condition and the ductile fracture possibility is also discussed. The results show that the mechanical heterogeneity of the weldment has large effects on the stress triaxiality and the driving force. The stress triaxiality and the driving force increase both with the increase of yielding stress and with the decrease of strain hardening property in evenmatched weldments. With a decrease of weld metal width, the stress triaxiality and the driving force increase for an undermatched weldment and decrease for an overmatched weldment. The stress triaxiality and the driving force increase with a decrease of weld metal width when the strain hardening property of base metal is larger than that of weld metal and decrease with a decrease of weld metal width when the strain hardening property of base metal is lower than that of weld metal.
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