The shape of telephone cord blisters

Yong Ni,Senjiang Yu,Hongyuan Jiang,Linghui He

doi:10.1038/ncomms14138

Yong Ni, Senjiang Yu + Show 2 more

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https://doi.org/10.1038/ncomms14138

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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.

Highlights

Formation of telephone cord blisters as a result of buckling delamination is widely observed in many compressed film-substrate systems
We assume that the shape of the telephone cord (TC) blister can be modelled as the postbuckling morphology of the thin plate clamped along such delamination boundary under equal biaxial residual compression (Fig. 1c)
We firstly determine the 3D shape of the TC blister by solving the Foppl-von Karman (FvK) equations for a plate of thickness h clamped along the delamination boundary in a curvilinear coordinate (Fig. 1c)

Summary

Introduction

Formation of telephone cord blisters as a result of buckling delamination is widely observed in many compressed film-substrate systems. Based on the Foppl-von Karman 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. A comprehensive study for the 3D TC morphology suggested that it could be approximately viewed as a sequence of connected segments of a circular buckle pinned at its centre[12] Such approximation predicted the ridge of the TC blister to be discontinuous, different from our following refined experimental observations wherein the ridge is continuous and its height is periodically changing. Such geometric feature becomes more significant in the case of larger waviness amplitude of the centreline, corresponding to a transition from the light TC blister to the heavy TC blister

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