Mechanical modeling and fracture analysis for a non-homogeneous weldment with a crack perpendicular to the interface

A new mechanical model is established for a non-homogeneous weldment with HAZs and fusion zones treated as functionally graded materials. The interface-perpendicular anti-plane fracture problems are analyzed for the HAZ and the weld metal, respectively, by the methods of Fourier integral transform and Cauchy singular integral equation. Lobatto–Chebyshev collocation method put forth by Erdogan and Gupta is employed to obtain numerical results of stress intensity factor (SIF). Parametric studies yield three conclusions: (1) overmatching is more beneficial than undermatching to the reduction of the SIF of a HAZ crack, however, the latter is more effective than the former in reducing the SIF of a weld-metal crack; (2) the optimum value of mismatch factor is 1.0, and values too greater or too smaller than this should be avoided in engineering design; (3) when the mismatch factor is unequal to 1.0, the SIF could be reduced by increasing the absolute value of the non-homogeneity parameters of HAZs.