Summary: We use a previously formulated solution of the Navier’s equation to calculate stress intensity factor in a notched bar bonded to a substrate. We evolve a procedure for determining the stress distribution. We validate the stress analysis in four-point bending by measuring surface strains for different combination of materials in the bilayer (the Young’s modulus ratio of the materials in the bilayer varied from 28 to 86). We also determine the stress intensity factor (SIF) experimentally using a notched photoelastic bar bonded to a substrate and validate our estimation of SIF.