Abstract: A generalized model of interfacial zone between bimaterials is presented. By virtue of this model, a penny shaped interface crack is investigated under torsion. Stress intensity factor is obtained by solving singular integral equation. Numerical examples are given to show the effects of material properties, interlayer thickness, and especially the distribution parameter k on the stress intensity factor.The comparison between Erdogan's results and our results shows that theinterlayer model presented in this...