An energy model of segmentation cracking of thin films

On the basis of analytical modelling of delamination of a thin film on a stretched substrate an energy model of film segmentation cracking has been formulated. The model focuses on a topological transformation between an intact and a damaged structure, rather than on a constitutive modelling of fracture itself. An energy transition condition should be satisfied in order for cracks to occur. The model provides a unique solution in the number of cracks for given material parameters. It has been validated by measuring the fracture energy of a silicon oxide thin film deposited on a poly(ethylene terephthalate) (PET) substrate, where a constant value of plastic shear stress at the film/substrate interface can be assumed.