Multiple Cracking Behavior of Brittle Films on Ductile Substrates Based on Weibull Statistical Distribution Model

Abstract

The film/substrate structure formed by depositing micro-nano brittle films on the flexible substrate has been applied in the field of flexible electronics. In the process of the film/substrate structure stretching, many cracks are produced, and a typical multiple cracking phenomenon appears. Based on the criterion of mixed mode cohesive cracking, we used a cohesive zone model combined with Weibull statistical distribution to replicate the initiation and propagation of cracks in real samples and simulate the delamination behavior at interfaces in this paper. Both the Young’s modulus and thickness of the film affect the crack onset strain, and the finite element simulation results are in consistent with the experimental results. The Young’s modulus and thickness of the film are inversely proportional to the crack onset strain. A larger film thickness leads to a lower saturated crack density. In addition, a larger shear stress also leads to the phenomenon of delamination between the interfaces. Utilization of the developed approach could benefit the in-depth understanding, estimation and regulation of the generation and propagation for the cracks in flexible electronics.

Keywords: film/substrate system, crack onset strain, multiple cracking, cohesive zone models, Weibull distribution