Abstract Numerical modelling of a photoelastic experiment is discussed. The experiment examined incompressible materials under plane strain conditions, which results in a simplified analysis owing to a vanishing of the bimaterial parameter. The photoelastic experiment used the stress freezing method to determine near tip stresses in interfacial cracks in bimaterial specimens. Different crack orientations were used to produce different mode mixities. Photoelastic fringe patterns were analyzed to determine the magnitude and phase angle of the complex stress intensity factor. These experiments were modeled using a finite element analysis to determine the field variables near the tips of the interfacial cracks. Magnitudes of the complex stress intensity factors are found from J integral values, derived using the domain integral approach, and the phase angles are determined using extrapolation of the bond line traction data to r =0. The results show that this approach is a useful way to characterize completely the complex stress intensity factor in incompressible linear elastic bimaterial combinations under plane strain conditions.