Tunable defect mode in a soft wrinkled bilayer system

Li, Guo-Yang; Zheng, Yang; Cao, Yanping

doi:10.1016/j.eml.2016.06.005

Cited by 12 publications

(5 citation statements)

References 28 publications

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“…Wrinkles can nucleate at "defects". 46,47 The results here show that the wrinkling morphology can be seeded by laser patterns, offering the possibility to engineer hydrophobicity, surface adhesion energy, and friction. 48−50 Finally, we performed a two-dimensional FFT analysis to quantitatively describe the alignment of laser-induced wrinkles vs random wrinkles created on a hot plate.…”

Section: ■ Results and Discussionmentioning

confidence: 75%

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Application of a Laser Cutter to Pattern Wrinkles on Polymer Films

Mondal

Liu

Shay

et al. 2020

ACS Appl. Polym. Mater.

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Wrinkling of thin films is a simple way to fabricate microscale topographical structures without the use of expensive lithographic processes or clean rooms. Such wrinkles have applications in surface wetting, adhesives, optics, and flexible electronics. It is possible to form wrinkles on a surface by heating a film stack of two or more layers featuring different Young's modulus and coefficient of thermal expansion (CTE). Wrinkles form over the entire surface due to the stresses arising from the mismatch in CTE between the layers. Here, we induce wrinkles only at specified locations of an aluminum/polystyrene film stack on a silicon wafer by delivering heat to targeted locations on the surface of the film via a laser beam from a conventional "laser cutter". Wrinkles form during irradiation within a circular spot defined by the laser without the need for additional heating. Rastering the laser beam across the surface forms various shapes such as circles, lines, and squares composed of individual wrinkles. The wrinkles have wavelengths ranging from 3.5 to 11.2 μm depending on the thickness of the metal and polymer films and laser power. Conventional theory predicts similar wavelength values, suggesting that they are driven by thermal expansion. The resolution of features formed by conventional laser ablation is closer to 50 μm; thus, wrinkling offers a way of patterning structures with "subablation" dimensions. With postheating, these wrinkles can extend into the pristine regions of the film with a direction and alignment seeded by the laser pattern. The discrete topographical patterns formed by the laser can alter the local mechanical, optical, and wetting properties for applications, including, antifouling surfaces, wettability gradients, and optics.

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Section: ■ Results and Discussionmentioning

confidence: 75%

“…The laser spots act as seed sites for the additional wrinkles to grow when heated on a hot plate. Wrinkles can nucleate at “defects”. , The results here show that the wrinkling morphology can be seeded by laser patterns, offering the possibility to engineer hydrophobicity, surface adhesion energy, and friction. − …”

Section: Results and Discussionmentioning

confidence: 82%

Application of a Laser Cutter to Pattern Wrinkles on Polymer Films

Mondal

Liu

Shay

et al. 2020

ACS Appl. Polym. Mater.

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“…7). As revealed in the previous studies [23,29], the first band gap in the bilayer with a homogeneous substrate mainly relies on the stress pattern instead of the magnitude of the stress.…”

Section: mentioning

confidence: 77%

“…Alireza and Faramarz [21] and the authors [23,29] have reported that a wrinkled bilayer system may serve a soft metamaterial to control the elastic wave propagation. In this letter, we investigate the propagation of elastic wave in the wrinkled stiff-film/composite-substrate bilayer system.…”

Section: Introductionmentioning

confidence: 99%

Wrinkling of a stiff film resting on a fiber-filled soft substrate and its potential application as tunable metamaterials

Zheng

Cao

et al. 2017

Extreme Mechanics Letters

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Mechanical self-assembly of ordered patterns via spontaneous buckling of thin-film/soft-substrate systems has received considerable interests in recent years. Here we study the wrinkling of a stiff film resting on a fiber-filled soft substrate. In particular, the effects of the cross-section dimension, spacing, and positions of fibers on the wrinkling patterns in the film/substrate bilayer system are investigated. We show that diverse wrinkling patterns, including sinusoidal wrinkling, period-doubling, period-tripling and mountain ridge modes, may occur at a small or moderate overall compression strain due to the inhomogeneous deformation in the substrate and they can be well controlled by tuning geometrical and physical parameters of the system. To illustrate the potential use of the wrinkling patterns revealed in this study, we investigate the elastic wave propagation in such a wrinkled bilayer using the Bloch wave theory. Our computational results show that diverse stress patterns generated in the soft composites give rise to a rich variety of band structures. Desired bandgaps of elastic waves can be achieved and tuned by simply designing the geometric parameters and controlling the external stimuli imposed to the soft metamaterials.

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“…These materials are usually hyperelastic, such as silicone rubber [ 19 , 20 , 21 ], polydimethylsiloxane (PDMS) [ 22 , 23 ] or photoelastic elastomer [ 24 , 25 ]. Pattern transformation resulting from the instability opens up a new method for the manufacturing of soft matters with adjustable acoustic, optical and electrical properties [ 26 , 27 , 28 , 29 , 30 , 31 ].…”

Section: Introductionmentioning

confidence: 99%

The Effect of Void Arrangement on the Pattern Transformation of Porous Soft Solids under Biaxial Loading

Qiu

Guo

et al. 2021

Materials

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Structural topology and loading condition have important influences on the mechanical behaviors of porous soft solids. The porous solids are usually set to be under uniaxial tension or compression. Only a few studies have considered the biaxial loads, especially the combined loads of tension and compression. In this study, porous soft solids with oblique and square lattices of circular voids under biaxial loadings were studied through integrated experiments and numerical simulations. For the soft solids with oblique lattices of circular voids, we found a new pattern transformation under biaxial compression, which has alternating elliptic voids with an inclined angle. This kind of pattern transformation is rarely reported under uniaxial compression. Introducing tensile deformation in one direction can hamper this kind of pattern transformation under biaxial loading. For the soft solids with square lattices of voids, the number of voids cannot change their deformation behaviors qualitatively, but quantitatively. In general, our present results demonstrate that void morphology and biaxial loading can be harnessed to tune the pattern transformations of porous soft solids under large deformation. This discovery offers a new avenue for designing the void morphology of soft solids for controlling their deformation patterns under a specific biaxial stress-state.

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Tunable defect mode in a soft wrinkled bilayer system

Cited by 12 publications

References 28 publications

Application of a Laser Cutter to Pattern Wrinkles on Polymer Films

Application of a Laser Cutter to Pattern Wrinkles on Polymer Films

Wrinkling of a stiff film resting on a fiber-filled soft substrate and its potential application as tunable metamaterials

The Effect of Void Arrangement on the Pattern Transformation of Porous Soft Solids under Biaxial Loading

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