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. 2017 Jan 20:8:14138.
doi: 10.1038/ncomms14138.

The shape of telephone cord blisters

Yong Ni  1 , Senjiang Yu  2 , Hongyuan Jiang  1 , Linghui He  1
Affiliations

The shape of telephone cord blisters

Yong Ni et al. Nat Commun. .

Abstract

Formation of telephone cord blisters as a result of buckling delamination is widely observed in many compressed film-substrate systems. Here we report a universal morphological feature of such blisters characterized by their sequential sectional profiles exhibiting a butterfly shape using atomic force microscopy. Two kinds of buckle morphologies, light and heavy telephone cord blisters, are observed and differentiated by measurable geometrical parameters. Based on the Föppl-von Kármán plate theory, the observed three-dimensional features of the telephone cord blister are predicted by the proposed approximate analytical model and simulation. The latter further replicates growth and coalescence of the telephone cord into complex buckling delamination patterns observed in the experiment.

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Figures

Figure 1
Figure 1. Schematic model for the shape of telephone cord blisters.
Fitting the projected area of (a) a light TC blister and (b) a heavy TC blister observed in SiAlNx films on glass substrates. (c) Sketch of the FvK model in a curvilinear coordinate under the clamping boundary condition along the boundary of the projected area. Scale bars in (a) and (b) are 30 and 50 μm, respectively.
Figure 2
Figure 2. Characterization of the TC blister shape.
Several sectional profiles perpendicular to the centreline are shown in the inserted modified AFM image 40 μm × 40 μm, which is updated by manually performing planefit offline of the original AFM image obtained by line-by-line (256 lines) scanning modes. The results from theory, simulation and AFM measurements are compared in a Ta film on glass substrates.
Figure 3
Figure 3. Measurable geometrical parameters.
b1/b2 and formula image as a function of A/λ characterize different undulatory shapes of the TC blisters: comparison between theory, simulation and experimental observations in various films including Ta, SiAlNx, Fe and Ni on glass substrates.
Figure 4
Figure 4. Morphologies of light and heavy TC blisters.
(a–c) AFM images. Scale bars are 10 μm. (d–f) Numerical simulation results with parameters b/h=49, λ/b=2, ɛm=0.005, and A/λ=0.04, 0.08 and 0.4.
See this image and copyright information in PMC

References

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