Sensitivity of the mode locking phenomenon to geometric imperfections during wrinkling of supported thin films

Saha, Sourabh K.

doi:10.1016/j.ijsolstr.2017.01.018

Title: Sensitivity of the mode locking phenomenon to geometric imperfections during wrinkling of supported thin films

Abstract

Although geometric imperfections have a detrimental effect on buckling, imperfection sensitivity has not been well studied in the past during design of sinusoidal micro and nano-scale structures via wrinkling of supported thin films. This is likely because one is more interested in predicting the shape/size of the resultant patterns than the buckling bifurcation onset strain during fabrication of such wrinkled structures. Herein, I have demonstrated that even modest geometric imperfections alter the final wrinkled mode shapes via the mode locking phenomenon wherein the imperfection mode grows in exclusion to the natural mode of the system. To study the effect of imperfections on mode locking, I have (i) developed a finite element mesh perturbation scheme to generate arbitrary geometric imperfections in the system and (ii) performed a parametric study via finite element methods to link the amplitude and period of the sinusoidal imperfections to the observed wrinkle mode shape and size. Based on this, a non-dimensional geometric parameter has been identified that characterizes the effect of imperfection on the mode locking phenomenon – the equivalent imperfection size. An upper limit for this equivalent imperfection size has been identified via a combination of analytical and finite element modeling. During compression of supportedmore »« less

Authors:

Publication Date:: Wed Mar 01 00:00:00 EST 2017

Research Org.:: Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)

Sponsoring Org.:: USDOE

OSTI Identifier:: 1550596

Alternate Identifier(s):: OSTI ID: 1367995; OSTI ID: 1398049

Report Number(s):: LLNL-JRNL-706663
Journal ID: ISSN 0020-7683; S0020768317300203; PII: S0020768317300203

Grant/Contract Number:: AC52-07NA27344; LLNL-JRNL-706663

Resource Type:: Published Article

Journal Name:: International Journal of Solids and Structures

Additional Journal Information:: Journal Name: International Journal of Solids and Structures Journal Volume: 109 Journal Issue: C; Journal ID: ISSN 0020-7683

Publisher:: Elsevier

Country of Publication:: United States

Language:: English

Subject:: 42 ENGINEERING; 36 MATERIALS SCIENCE; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 77 NANOSCIENCE AND NANOTECHNOLOGY; Wrinkles; Buckling; Bilayer wrinkling; Mesh perturbation; Perturbation sensitivity

Citation Formats


                    Saha, Sourabh K. Sensitivity of the mode locking phenomenon to geometric imperfections during wrinkling of supported thin films.  United States: N. p., 2017. 
Web.  doi:10.1016/j.ijsolstr.2017.01.018.

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                    Saha, Sourabh K. Sensitivity of the mode locking phenomenon to geometric imperfections during wrinkling of supported thin films.  United States.  https://doi.org/10.1016/j.ijsolstr.2017.01.018

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                    Saha, Sourabh K. Wed .  
"Sensitivity of the mode locking phenomenon to geometric imperfections during wrinkling of supported thin films".  United States.  https://doi.org/10.1016/j.ijsolstr.2017.01.018.

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@article{osti_1550596,

  title        = {Sensitivity of the mode locking phenomenon to geometric imperfections during wrinkling of supported thin films},

  author       = {Saha, Sourabh K.},

  abstractNote = {Although geometric imperfections have a detrimental effect on buckling, imperfection sensitivity has not been well studied in the past during design of sinusoidal micro and nano-scale structures via wrinkling of supported thin films. This is likely because one is more interested in predicting the shape/size of the resultant patterns than the buckling bifurcation onset strain during fabrication of such wrinkled structures. Herein, I have demonstrated that even modest geometric imperfections alter the final wrinkled mode shapes via the mode locking phenomenon wherein the imperfection mode grows in exclusion to the natural mode of the system. To study the effect of imperfections on mode locking, I have (i) developed a finite element mesh perturbation scheme to generate arbitrary geometric imperfections in the system and (ii) performed a parametric study via finite element methods to link the amplitude and period of the sinusoidal imperfections to the observed wrinkle mode shape and size. Based on this, a non-dimensional geometric parameter has been identified that characterizes the effect of imperfection on the mode locking phenomenon – the equivalent imperfection size. An upper limit for this equivalent imperfection size has been identified via a combination of analytical and finite element modeling. During compression of supported thin films, the system gets “locked” into the imperfection mode if its equivalent imperfection size is above this critical limit. For the polydimethylsiloxane/glass bilayer with a wrinkle period of 2 µm, this mode lock-in limit corresponds to an imperfection amplitude of 32 nm for an imperfection period of 5 µm and 8 nm for an imperfection period of 0.8 µm. Interestingly, when the non-dimensional critical imperfection size is scaled by the bifurcation onset strain, the scaled critical size depends solely on the ratio of the imperfection to natural periods. Furthermore, the computational data generated here can be generalized beyond the specific natural periods and bilayer systems studied to enable deterministic design of a variety of wrinkled micro and nano-scale structures.},

  doi          = {10.1016/j.ijsolstr.2017.01.018},

  journal      = {International Journal of Solids and Structures},

  number       = C,

  volume       = 109,

  place        = {United States},

  year         = {Wed Mar 01 00:00:00 EST 2017},

  month        = {Wed Mar 01 00:00:00 EST 2017}

}

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Works referencing / citing this record:

Direct numerical simulation of buckling instability of thin films on a compliant substrate
journal, April 2019

Nikravesh, Siavash; Ryu, Donghyeon; Shen, Yu-Lin
Advances in Mechanical Engineering, Vol. 11, Issue 4
DOI: 10.1177/1687814019840470

Surface Instability of Composite Thin Films on Compliant Substrates: Direct Simulation Approach
journal, September 2019

Nikravesh, Siavash; Ryu, Donghyeon; Shen, Yu-Lin
Frontiers in Materials, Vol. 6
DOI: 10.3389/fmats.2019.00214

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Title: Sensitivity of the mode locking phenomenon to geometric imperfections during wrinkling of supported thin films

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