Surface wrinkling of a film coated to a graded substrate

We study the surface wrinkling of a stiff thin elastic film bonded to a compliant graded elastic substrate subject to compressive stress generated either by compression or growth of the bilayer. Our aim is to clarify the influence of the modulus gradient on the onset and surface pattern in this bila...

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Main Authors: Liu, R-C, Liu, Y, Goriely, A
Format: Journal article
Language:English
Published: Elsevier 2024
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author Liu, R-C
Liu, Y
Goriely, A
author_facet Liu, R-C
Liu, Y
Goriely, A
author_sort Liu, R-C
collection OXFORD
description We study the surface wrinkling of a stiff thin elastic film bonded to a compliant graded elastic substrate subject to compressive stress generated either by compression or growth of the bilayer. Our aim is to clarify the influence of the modulus gradient on the onset and surface pattern in this bilayer. Within the framework of finite elasticity, an exact bifurcation condition is obtained using the Stroh formulation and the surface impedance matrix method. Further analytical progress is made by focusing on the case of short wavelength limit for which the Wentzel–Kramers–Brillouin method can be used to resolve the eigenvalue problem of ordinary differential equations with variable coefficients. An explicit bifurcation condition is obtained from which the critical buckling load and the critical wavelength are derived asymptotically. In particular, we consider two distinct situations depending on the ratio 𝛽 of the shear modulus at the substrate surface to that at infinity. If 𝛽 is of (1) or small, the parameters related to modulus gradient all appear in the higher-order terms and play an insignificant role in the bifurcation. In that case, it is the modulus ratio between the film and substrate surface that governs the onset of surface wrinkling. If, however, 𝛽 ≫ 1, the modulus gradient affects the critical condition through leading-order terms. Through our analysis we unravel the influence of different material and geometric parameters, including the modulus gradient, on the bifurcation threshold and the associated wavelength which can be of importance in many biological and technological settings.
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spelling oxford-uuid:82dc3153-48f1-4c41-b657-08d98c8320882024-04-15T09:28:02ZSurface wrinkling of a film coated to a graded substrateJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:82dc3153-48f1-4c41-b657-08d98c832088EnglishSymplectic ElementsElsevier2024Liu, R-CLiu, YGoriely, AWe study the surface wrinkling of a stiff thin elastic film bonded to a compliant graded elastic substrate subject to compressive stress generated either by compression or growth of the bilayer. Our aim is to clarify the influence of the modulus gradient on the onset and surface pattern in this bilayer. Within the framework of finite elasticity, an exact bifurcation condition is obtained using the Stroh formulation and the surface impedance matrix method. Further analytical progress is made by focusing on the case of short wavelength limit for which the Wentzel–Kramers–Brillouin method can be used to resolve the eigenvalue problem of ordinary differential equations with variable coefficients. An explicit bifurcation condition is obtained from which the critical buckling load and the critical wavelength are derived asymptotically. In particular, we consider two distinct situations depending on the ratio 𝛽 of the shear modulus at the substrate surface to that at infinity. If 𝛽 is of (1) or small, the parameters related to modulus gradient all appear in the higher-order terms and play an insignificant role in the bifurcation. In that case, it is the modulus ratio between the film and substrate surface that governs the onset of surface wrinkling. If, however, 𝛽 ≫ 1, the modulus gradient affects the critical condition through leading-order terms. Through our analysis we unravel the influence of different material and geometric parameters, including the modulus gradient, on the bifurcation threshold and the associated wavelength which can be of importance in many biological and technological settings.
spellingShingle Liu, R-C
Liu, Y
Goriely, A
Surface wrinkling of a film coated to a graded substrate
title Surface wrinkling of a film coated to a graded substrate
title_full Surface wrinkling of a film coated to a graded substrate
title_fullStr Surface wrinkling of a film coated to a graded substrate
title_full_unstemmed Surface wrinkling of a film coated to a graded substrate
title_short Surface wrinkling of a film coated to a graded substrate
title_sort surface wrinkling of a film coated to a graded substrate
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AT liuy surfacewrinklingofafilmcoatedtoagradedsubstrate
AT gorielya surfacewrinklingofafilmcoatedtoagradedsubstrate