scholarly journals Mechanical Analysis and Experimental Studies of the Transverse Strain in Wrinkled Metallic Thin Films

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 427
Author(s):  
Tongxin Nie ◽  
Baomin Wang ◽  
Bo Liu ◽  
Yali Xie ◽  
Huali Yang ◽  
...  

The wrinkling structures, which can greatly improve the stretchability of the metallic thin films, have been widely used in the preparation of stretchable devices. However, the artificial wrinkling structures are often accompanied by the generation of microcracks, which seriously affect the performance of the devices. In this work, by establishing the corresponding model, the transverse strain of the longitudinally prestrained continuous film and the strip film is mechanically analyzed, which is verified by experimental results; for the strain of blank substrate, the error of the model was about 3.7%. It is difficult to avoid the generation of microcracks with continuous films, but strip films can avoid the generation of microcracks to a certain extent. The experimental results illustrate the various factors affecting the generation of microcracks. The transverse strain of the film is proportional to the substrate’s Young’s modulus, Poisson’s ratio, thickness, and prestrain and is basically inversely proportional to the strip film’s Young’s modulus, thickness, and strip interval. Our results provide deeper knowledge for choosing proper metallic materials to fabricate stretchable wrinkled devices.

Coatings ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 153
Author(s):  
Chuen-Lin Tien ◽  
Tsai-Wei Lin

This paper proposes a measuring apparatus and method for simultaneous determination of the thermal expansion coefficient and biaxial Young’s modulus of indium tin oxide (ITO) thin films. ITO thin films simultaneously coated on N-BK7 and S-TIM35 glass substrates were prepared by direct current (DC) magnetron sputtering deposition. The thermo-mechanical parameters of ITO thin films were investigated experimentally. Thermal stress in sputtered ITO films was evaluated by an improved Twyman–Green interferometer associated with wavelet transform at different temperatures. When the heating temperature increased from 30 °C to 100 °C, the tensile thermal stress of ITO thin films increased. The increase in substrate temperature led to the decrease of total residual stress deposited on two glass substrates. A linear relationship between the thermal stress and substrate heating temperature was found. The thermal expansion coefficient and biaxial Young’s modulus of the films were measured by the double substrate method. The results show that the out of plane thermal expansion coefficient and biaxial Young’s modulus of the ITO film were 5.81 × 10−6 °C−1 and 475 GPa.


2018 ◽  
Vol 233 ◽  
pp. 00025
Author(s):  
P.V. Polydoropoulou ◽  
K.I. Tserpes ◽  
Sp.G. Pantelakis ◽  
Ch.V. Katsiropoulos

In this work a multi-scale model simulating the effect of the dispersion, the waviness as well as the agglomerations of MWCNTs on the Young’s modulus of a polymer enhanced with 0.4% MWCNTs (v/v) has been developed. Representative Unit Cells (RUCs) have been employed for the determination of the homogenized elastic properties of the MWCNT/polymer. The elastic properties computed by the RUCs were assigned to the Finite Element (FE) model of a tension specimen which was used to predict the Young’s modulus of the enhanced material. Furthermore, a comparison with experimental results obtained by tensile testing according to ASTM 638 has been made. The results show a remarkable decrease of the Young’s modulus for the polymer enhanced with aligned MWCNTs due to the increase of the CNT agglomerations. On the other hand, slight differences on the Young’s modulus have been observed for the material enhanced with randomly-oriented MWCNTs by the increase of the MWCNTs agglomerations, which might be attributed to the low concentration of the MWCNTs into the polymer. Moreover, the increase of the MWCNTs waviness led to a significant decrease of the Young’s modulus of the polymer enhanced with aligned MWCNTs. The experimental results in terms of the Young’s modulus are predicted well by assuming a random dispersion of MWCNTs into the polymer.


1999 ◽  
Vol 594 ◽  
Author(s):  
T. Y. Zhang ◽  
Y. J. Su ◽  
C. F. Qian ◽  
M. H. Zhao ◽  
L. Q. Chen

AbstractThe present work proposes a novel microbridge testing method to simultaneously evaluate the Young's modulus, residual stress of thin films under small deformation. Theoretic analysis and finite element calculation are conducted on microbridge deformation to provide a closed formula of deflection versus load, considering both substrate deformation and residual stress in the film. Silicon nitride films fabricated by low pressure chemical vapor deposition on silicon substrates are tested to demonstrate the proposed method. The results show that the Young's modulus and residual stress for the annealed silicon nitride film are respectively 202 GPa and 334.9 MPa.


2016 ◽  
Vol 18 (31) ◽  
pp. 21508-21517 ◽  
Author(s):  
Xiao-Ye Zhou ◽  
Bao-Ling Huang ◽  
Tong-Yi Zhang

Surfaces of nanomaterials play an essential role in size-dependent material properties.


1994 ◽  
Vol 60 (572) ◽  
pp. 1108-1113
Author(s):  
Hidetoshi Yanai ◽  
Nobuyuki Kishine ◽  
Yukari Komaba ◽  
Yukitaka Murakami

2012 ◽  
Vol 455-456 ◽  
pp. 8-12 ◽  
Author(s):  
Bin Li ◽  
Ping Xie ◽  
Su Ying Zhang ◽  
Ding Quan Liu

A mechanically robust infrared high-index coating material is essential to the infrared interference coatings. Lead germanium telluride (Pb1-xGexTe) is a pseudo-binary alloy of IV-VI narrow gap semiconductors of PbTe and GeTe. In our investigation, the hardness and Young’s modulus of thin films of Pb1-xGexTe, which were deposited on silicon substrates using electron beam evaporation, were identified by means of nanoindentation measurement. It is demonstrated that layers of Pb1-xGexTe have greater hardness and Young’s modulus compared with those of PbTe. These mechanical behaviors of layers can be linked to a ferroelectric phase transition from a cubic paraelectric phase to a rhombohedral, ferroelectric phase. Moreover, the strength loss in the layers of Pb1-xGexTe can be also explained in light of strong localized elastic-strain fields in concentrated solid solutions.


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