Abstract: In this paper, overmatched welded joints with a crack in a hardened HAZ, and welded joints of dissimilar metals jointed through a harder transition layer with a croak in it are simplified and modeled as heterogeneous plates with a sandwiched hard layer containing a centre crack parallel to the bonds. The strain field and the COD in the heterogeneous centre-cracked plated are studied both numerically by elastoplastle FEM and experimentally by Moiré method. The results obtained show that the effect of the material heterogeneity upon the COD is non-negligible especially in case of the nominal stress or nominal strain being comparatively high. The COD decreases with the increasing sandwiched hard layer width.

Key words: COD, 非均质, 焊接接头, 裂纹, 有限元