Fracture analysis for a non-homogeneous weldment with a crack parallel to the interface

Fracture modeling and analysis are of significance in the design and evaluation of weldments. Based on a new four-zone model, the present work performs anti-plane fracture analysis on a non-homogeneous weldment consisting of four different kinds of zones: base metal, heat affected zone (HAZ), fusion zone and weld metal. The HAZs and fusion zones are modeled as functionally graded materials. A crack parallel to the interface is assumed to be in the HAZ or weld metal. The crack problem is solved by the methods of Fourier integral transform and dual integral equation. Parametric studies on the stress intensity factors yield two conclusions for the current fracture model of the four-zone weldment. (i) The optimal value of the mismatch factor is 1.0. The increase in mismatch factor will decrease the driving force of a HAZ crack, but it will enhance that of a weld-metal crack. In engineering, mismatch factors too larger or too smaller than 1.0 should be avoided. (ii) The effect of non-homogeneity parameter embodies that of the relative stiffness of the crack-tip region. Stiffer crack-tip region may induce larger driving force for the crack.