Thin film and substrate cracking under the influence of externally applied loads

Cracking in thin film systems subject to residual tension is examined. The existing solution for the case of a crack tip in the substrate is modified to provide a solution of greater accuracy. The influence of external tensile loads on thin film and substrate cracking is examined. An approximate superposition scheme is presented for the determination of the energy release rate. Crack arrest is examined and parameters for determining the possibility of crack arrest are presented. For compliant films it was found that crack arrest does not occur when the substrate stress has the same magnitude as the residual stress. The influence of externally applied loads on crack channelling and conditions under which channelling will occur in the substrate are presented.