Fracture characterization of inhomogeneous wrinkled metallic films deposited on soft substrates
Fracture characterization of inhomogeneous wrinkled metallic films deposited on soft substrates
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DOI：
10.1088/1361-6463/aa95cb
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发表时间：
2017-11
期刊：
影响因子：
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通讯作者：
Hiroshi Kishida;S. Ishizaka;Takumi Nagakura;Hiroaki Suzuki;A. Yonezu
中科院分区：
文献类型：
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作者：
Hiroshi Kishida;S. Ishizaka;Takumi Nagakura;Hiroaki Suzuki;A. Yonezu
研究了聚二甲基硅氧烷（PDMS）软基片上褶皱金属薄膜的断裂特性。特别是，在拉伸变形过程中的褶皱膜的裂纹密度进行了检查。为了获得更好的金属薄膜的变形性，首先建立了一种在PDMS软基片上制备褶皱薄膜的方法。在这项研究中制备的铜（Cu）纳米薄膜具有褶皱的几何形状，这在确定大的弹性变形的程度中起着关键作用。为了产生褶皱结构，使用具有聚合物牺牲层的湿法蚀刻。首先将牺牲层沉积到硅橡胶片上。在该层的固化过程中，施加压缩应变，使得硬化的表面层屈曲，并且获得褶皱形式。随后，使用PDMS溶液覆盖该层以形成褶皱的PDMS基底。最后，将Cu膜沉积到褶皱的PDMS上，从而在柔性PDMS衬底上制备褶皱的Cu膜。单轴拉伸试验的使用导致在膜的褶皱结构中的应力集中区处产生膜裂纹。当拉伸载荷增加时，裂纹数量增加。有人发现，裂纹密度的增加是密切相关的不均匀性的褶皱结构。使用FEM（有限元法）计算研究了裂纹密度的这种趋势，使得本研究建立了可用于预测拉伸变形期间裂纹密度增加的简单力学模型。该模型通过几个实验，使用各种皱纹图案进行了验证。所提出的力学模型可能是有用的预测裂纹密度的褶皱金属薄膜拉伸载荷。
This study investigated the fracture properties of wrinkled metallic films on a polydimethylsiloxane (PDMS) soft substrate. In particular, the crack density of the wrinkled film during tensile deformation was examined. In order to achieve better deformability of metallic thin films, a method to fabricate a wrinkled thin film on a PDMS soft substrate was first established. The copper (Cu) nano-film fabricated in this study possessed a wrinkled geometry, which plays a critical role in determining the extent of large elastic deformation. To create the wrinkled structure, wet-etching with a polymeric sacrificial layer was used. A sacrificial layer was first deposited onto a silicone rubber sheet. During the curing process of the layer, a compressive strain was applied such that the hardened surface layer buckled, and a wrinkled form was obtained. Subsequently, a PDMS solution was used to cover the layer in order to form a wrinkled PDMS substrate. Finally, the Cu film was deposited onto the wrinkled PDMS, such that the wrinkled Cu film on a soft PDMS substrate was fabricated. The use of uni-axial tensile tests resulted in film crack generation at the stress concentration zone in the wrinkled structure of the films. When the tensile loading was increased, the number of cracks increased. It was found that the increase in crack density was strongly related to the inhomogeneous nature of the wrinkled structure. Such a trend in crack density was investigated using FEM (finite element method) computations, such that this study established a simple mechanical model that may be used to predict the increase in crack density during tensile deformation. This model was verified through several experiments using various wrinkle patterns. The proposed mechanical model may be useful to predict the crack density of a wrinkled metallic film subject to tensile loading.