An elastic–plastic shear lag model for fracture of layered coatings

We present a phenomenological model describing cracking under uniaxial tensile strain of a brittle thin film on a deformable substrate with an elastic–plastic interface layer. The model yields an analytical solution predicting average crack density and average crack opening as a function of applied strain and material parameters. The model has been applied to experimental data for cracks in thin SiO x films on PET substrates.