研究者詳細 - 永島　壮

論文 - 永島　壮

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Capillarity-induced fold localization in film–substrate systems 査読有り

S. Nagashima, R. Ota, S. Matsubara, D. Okumura

Interface Focus 2025年3月

Tunable wrinkles in diamond-like carbon films on PDMS substrates 査読有り

Nagashima, S; Hasebe, T; Hotta, A; Suzuki, T

Diam. Relat. Mater. 151 巻頁： 11855 2025年1月

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Diamond and Related Materials

Diamond-like carbon (DLC) films are widely used in engineering applications owing to their excellent mechanical, optical, and biological properties. However, the simple deposition of a DLC film on a soft polymer, including poly(dimethylsiloxane) (PDMS), results in a coarsened surface composed of instability-induced hierarchical wrinkles with limited ability to adjust the dimensions. Overcoming this issue would help create fabrication opportunities for functional surfaces. Here, we demonstrate the controlled formation of wrinkles with tunable wavelengths and amplitudes on the surface of DLC-coated PDMS substrates. Pre-treatment of the substrates with Ar plasma prior to film deposition allows for the formation of wrinkles without structural hierarchy. The wavelength and amplitude can be controlled by adjusting the duration of the plasma treatment while maintaining the film thickness constant. The static contact angles of water droplets on the wrinkled surfaces remain nearly constant regardless of the wavelength of the wrinkles. These tunable wrinkles in DLC films on PDMS substrates have potential engineering applications, including cell scaffolds.

DOI： 10.1016/j.diamond.2024.111855

Web of Science

Scopus

水フィラメントに駆動されるリンクル・フォールド変態の数値解析査読有り

太田陸斗, 永島壮, 松原成志朗, 奥村大

計算数理工学論文集 24 巻頁： 05-241213 2024年12月

クリースの形成に及ぼすひずみ第二不変量の影響査読有り

岡村太暉, 松原成志朗, 永島壮, 奥村大

計算数理工学論文集 24 巻頁： 06-241213 2024年12月

ノンレシプロカルゲルの異常ポインティング効果査読有り

野々垣翔真, Yunlei Zhang, 松原成志朗, 永島壮, 石田康博, 奥村大

計算数理工学論文集 24 巻頁： 04-241213 2024年12月

Inhomogeneous instability patterns in polyacrylamide hydrogel bilayers 査読有り

S. Nagashima, W. Uchiyama, S. Hayashi, S. Matsubara, D. Okumura

Mech. Eng. J 2024年11月

Crease instability in Gent-Gent hyperelastic materials Open Access

Matsubara, S; Kobayashi, K; Ishida, T; Nagashima, S; Okumura, D

Int. J. Mech. Sci. 280 巻頁： 109549 - 109549 2024年10月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：International Journal of Mechanical Sciences

We study the crease instability of an incompressible Gent-Gent elastomer under general loading conditions. The Gent-Gent model has two distinct characteristics: the logarithmic nonlinearity triggered by I2 energy term and the strain hardening due to limiting chain extensibility. By performing finite element analysis combined with an evaluation of surface tension, we investigate the effects of the two characteristics on the critical creasing onset and the creasing onset delayed by surface tension. The results show that uniaxial compression induces logarithmic nonlinearity that accelerates the critical creasing onset, whereas equibiaxial compression hastens the initiation of strain hardening that delays the critical creasing onset. In addition, logarithmic nonlinearity mitigates the delay in creasing onset caused by surface tension under the uniaxial condition, and strain hardening suppresses creasing in cooperation with surface tension under the equibiaxial condition. Conversely, under the plane strain condition, two characteristics have little effect on the creasing onset delayed by surface tension.

DOI： 10.1016/j.ijmecsci.2024.109549

Open Access

Web of Science

Scopus

Deformation in the wrinkle-crease transformation 査読有り

Ishida, T; Matsubara, S; Nagashima, S; Okumura, D

Int. J. Solids Struct. 298 巻頁： 112876 - 112876 2024年7月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：International Journal of Solids and Structures

We investigate deformation in the wrinkle–crease transformation to reveal the missing link between the wrinkling and creasing instabilities, which occur on the surface of elastomers under compression. Plane-strain finite element (FE) analysis is performed by combining a nonlinear perturbation approach to find two bifurcated solutions for the flat surface in a metastable state. The first solution is the stable deformation path for crease evolution, and the second solution is the previously unknown unstable deformation path from wrinkling to creasing. The two deformation paths are not independent, and they are connected at the critical strain for creasing εC. The resulting deformation at εC acts as a precursive deformation to cause creasing. Although the unstable path is initiated by the wrinkling instability as a bifurcation, the creasing instability (i.e., εC) is interpreted as the singular point at which the unstable path switches to the stable path. A chain reaction model is developed to describe the mechanism and deformation of the wrinkle–crease transformation, and it shows good agreement with the FE prediction within an inevitable limitation of FEs.

DOI： 10.1016/j.ijsolstr.2024.112876

Web of Science

Scopus

Computational and physical aspects for the occurrence of crease in an elastomer under general loading conditions 査読有り

Matsubara, S; Ogino, A; Nagashima, S; Okumura, D

Int. J. Solids Struct. 288 巻 2024年2月

記述言語：英語出版者・発行元：International Journal of Solids and Structures

We study the occurrence of crease in an elastomer under three loading conditions from both computational and physical points of view. A two-dimensional finite element analysis, including a perturbation force-based approach, is performed to detect the stable creased state, where the crease formation is completed. A mesh convergence study for the energy release and crease depth in the creased state provides a guideline for the finite element mesh requisite for predicting the occurrence of crease. We also visualize the mesh convergence for the critical creasing onset by plotting the set of compressive strain and mesh resolution at the point where the energy release is zero. In addition, the present evaluation method of the surface tension using the energy release and surface area change for an elastomer with a traction-free surface yields a good prediction for the creasing onset delayed by surface tension without additional numerical implementations or adjustment parameters. This facilitates the comprehensive study of the creasing onset delayed by the surface tension under general loading conditions. The results reveal that tensile deformation in the out-of-plane direction encourages the retardation of the creasing onset via the extension of the width and the energy emission. We further demonstrate that energetically preferential crease interval can be used to evaluate the spacing between creases delayed by moderate surface tension.

DOI： 10.1016/j.ijsolstr.2023.112610

Web of Science

Scopus

表面張力による固体と液体の相互運動のフェーズフィールド解析

纐纈拓己, 中谷彰宏, 土井祐介, 永島壮

関西支部講演会講演論文集 2024.99 巻 ( 0 ) 頁： 20207 2024年

記述言語：日本語出版者・発行元：一般社団法人日本機械学会

<p>現在，固体の形状の変化を利用した例として，二次元テンプレートを三次元構造物へ自己組織化するという技術が注目されている．液体と固体の間に作用する表面張力が，固体の構造に影響を及ぼすことが分かっている．本研究では構造の時間変化を直接扱うことができるフェーズフィールド法を用いて，固体が動いた場合の液体の挙動の解析を行った．</p>

DOI： 10.1299/jsmekansai.2024.99.20207

CiNii Research

均質化解析によるノンレシプロカルゲルの引張・圧縮非対称性評価

布施卓馬, 松原成志朗, 永島壮, 奥村大

計算数理工学論文集 23 巻 ( 0 ) 頁： 137 - 142 2023年11月

ノンレシプロカルゲルの円筒押込み大変形解析

野々垣翔真, 松原成志朗, 永島壮, 奥村大

計算数理工学論文集 23 巻 ( 0 ) 頁： 123 - 128 2023年11月

クリースの発達過程に対する影響因子の調査査読有り

石田竜也, 永島壮, 松原成志朗, 奥村大

計算数理工学論文集 23 巻頁： 20-231124 2023年11月

Visualization and analysis of skin strain distribution in various human facial actions 査読有り

T. Misu, H. Ishihara, S. Nagashima, Y. Doi and A. Nakatani

Mech. Eng. J. 2023年9月

Time-swelling superposition principle for the linear viscoelastic properties of polyacrylamide hydrogels 査読有り

S. Matsubara, A. Takashima, S. Nagashima, S. Ida, H. Tanaka, M. Uchida and D. Okumura

Adv. Struct. Mater. 2023年8月

Bio-Inspired Instability-Induced Hierarchical Patterns Having Tunable Anisotropic Wetting Properties《掲載号Front Cover選出》査読有り

Nagashima, S; Suzuki, K; Matsubara, S; Okumura, D

Adv. Mater. Interfaces 10 巻 ( 14 ) 頁： 2300039 2023年5月

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Advanced Materials Interfaces

This paper introduces a method for the bottom-up fabrication of bio-inspired hierarchical patterns having tunable anisotropic wetting properties. The method exploits the surface instability of bilayers comprising a gold nanofilm attached to a substantially prestretched elastomer substrate. Upon film formation, highly aligned wrinkles spontaneously form on the surface owing to the surface instability driven by the compressive residual stress in the film. Thereafter, uniaxial compressive strain is applied to the film by prestretch relaxation of the substrate, which generates an array of high-aspect-ratio ridges on the surface. Consequently, hierarchical patterns comprising unidirectionally aligned ridges covered with wrinkles are obtained. Water droplets placed on surfaces having the aforementioned hierarchical patterns show direction-dependent contact angles, resulting in elongated shapes, which indicates the presence of anisotropic wetting properties. The magnitude of wetting anisotropy can be tuned by simple control of the applied compressive strain and film thickness.

DOI： 10.1002/admi.202300039

Web of Science

Scopus

Self-Wrinkling in Polyacrylamide Hydrogel Bilayers《掲載号Supplementary Cover選出》査読有り

Nagashima, S; Akamatsu, N; Cheng, XF; Matsubara, S; Ida, S; Tanaka, H; Uchida, M; Okumura, D

Langmuir 39 巻 ( 11 ) 頁： 3942 - 3950 2023年3月

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Langmuir

Swelling of a gel film attached to a soft substrate can induce surface instability, which results in the formation of highly ordered patterns such as wrinkles and folds. This phenomenon has been exploited to fabricate functional devices and rationalize morphogenesis. However, obtaining centimeter-scale patterns without immersing the film in a solvent remains challenging. Here, we show that wrinkles with wavelengths of up to a few centimeters can be spontaneously created during the open-air fabrication of film-substrate bilayers of polyacrylamide (PAAm) hydrogels. When the film of an aqueous pregel solution of acrylamide prepared on the PAAm hydrogel substrate undergoes open-air gelation, hexagonally packed dimples initially emerge on the surface, which later evolve into randomly oriented wrinkles. The formation of such self-organized patterns can be attributed to the surface instability resulting from autonomous water transport in the bilayer system during open-air fabrication. The temporal evolution of the patterns can be ascribed to an increase in overstress in the hydrogel film due to continued water uptake. The wrinkle wavelength can be controlled in the centimeter-scale range by adjusting the film thickness of the aqueous pregel solution. Our self-wrinkling method provides a simple mechanism for the generation of swelling-induced centimeter-scale wrinkles without requiring an external solvent, which is unachievable with conventional approaches.

DOI： 10.1021/acs.langmuir.2c03264

Web of Science

Scopus

PubMed

リッジパターン変態のプレストレッチ依存性と分岐座屈特性査読有り

田中大地, 若林駿人, 松原成志朗, 永島壮, 奥村大

計算数理工学論文集 22 巻頁： 117 - 122 2022年12月

薄膜リンクル招待有り

永島壮

材料 71 巻 ( 8 ) 頁： 727 - 727 2022年8月

材料シンポジウム「若手学生研究発表会」招待有り

永島壮, 野口泰隆

材料 71 巻 ( 4 ) 頁： 415 - 415 2022年4月

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