Modeling the buckling and delamination of thin films

TL;DR

This paper numerically investigates the buckling and delamination behaviors of thin elastic films on rigid substrates, revealing how strain, Poisson ratio, and interface properties influence pattern formation and stability.

Contribution

It introduces a detailed numerical model that captures buckling and delamination patterns, including novel insights into the effects of mismatch and in-plane relaxation.

Findings

Different buckling configurations depend on strain and Poisson ratio.

Delamination patterns such as 'telephone-cord' and 'brain-like' are reproduced.

Pattern morphology is controlled by mismatch and in-plane relaxation.

Abstract

I study numerically the problem of delamination of a thin film elastically attached to a rigid substrate. A nominally flat elastic thin film is modeled using a two-dimensional triangular mesh. Both compression and bending rigidities are included to simulate compression and bending of the film. The film can buckle (i.e., abandon its flat configuration) when enough compressive strain is applied. The possible buckled configurations of a piece of film with stripe geometry are investigated as a function of the compressive strain. It is found that the stable configuration depends strongly on the applied strain and the Poisson ratio of the film. Next, the film is considered to be attached to a rigid substrate by springs that can break when the detaching force exceeds a threshold value, producing the partial delamination of the film. Delamination is induced by a mismatch of the relaxed configurations of film and substrate. The morphology of the delaminated film can be followed and compared with available experimental results as a function of model parameters. `Telephone-cord', polygonal, and `brain-like' patterns qualitatively similar to experimentally observed configurations are obtained in different parameter regions. The main control parameters that select the different patterns are the mismatch between film and substrate and the degree of in-plane relaxation within the unbuckled regions.