  The shear strength of a pre-cracked sandwich layer is predicted, assuming
that the layer is linear elastic or elastic-plastic, with yielding
characterized by either J2 plasticity theory or by a strip-yield model. The
substrates are elastic and of dissimilar modulus to that of the layer. Two
geometries are analysed: (i) a semi-infinite crack in a sandwich layer,
subjected to a remote mode II K-field and (ii) a centre-cracked sandwich plate
of finite width under remote shear stress. For the semi-infinite crack, the
near tip stress field is determined as a function of elastic mismatch, and
crack tip plasticity is either prevented (the elastic case) or is duly
accounted for (the elastic-plastic case). Analytical and numerical solutions
are then obtained for the centre-cracked sandwich plate of finite width. First,
a mode II K-calibration is obtained for a finite crack in the elastic sandwich
layer. Second, the analysis is extended to account for crack tip plasticity via
a mode II strip-yield model of finite strength and of finite toughness. The
analytical predictions are verified by finite element simulations and a failure
map is constructed in terms of specimen geometry and crack length.
