Abstract: The path-independence property of the J-integral for a non-homogeneous panel with a sandwiched hard layer containing a centre crack parallel to the interfaces, which is a simplified model of some typical welded joints and the validity of are investigated by means of elasto-plastic FEM with the view of applying the J-integral method to the safety assment of welded joints with mechanial non-homogeneity. It is shown that the J-integral remains path-independent and the expression of the J-integral as the rate of decrease of indent of potential energy, is still applicable in spite, of the non-homogeneity. The path independence of J in such a non-homogeneous environment is also confirmed mathematically. The effect of the mechanical non-homogeneity upon the J-integral values is studied. It is concluded that the yielding of the two soft zones between which the. Hard layer is sandwiched tends to make the J values increase; the smaller the relative hard layer width; h/2 a , the larger is the J value at the same load because the degree of yielding of the soft zones varies from h/2a to h/2a.