scholarly journals Buckling of a stiff thin film on an elastic graded compliant substrate

2017 ◽  
Vol 473 (2208) ◽  
pp. 20170410 ◽  
Author(s):  
Zhou Chen ◽  
Weiqiu Chen ◽  
Jizhou Song
Keyword(s):  
Thin Film ◽  
Analytical Model ◽  
Compressive Strain ◽  
Period Doubling ◽  
Stretchable Electronics ◽  
Element Analysis ◽  
Compliant Substrate ◽  
Material Parameters ◽  
Plane Compression ◽  
Critical Buckling Strain

The buckling of a stiff film on a compliant substrate has attracted much attention due to its wide applications such as thin-film metrology, surface patterning and stretchable electronics. An analytical model is established for the buckling of a stiff thin film on a semi-infinite elastic graded compliant substrate subjected to in-plane compression. The critical compressive strain and buckling wavelength for the sinusoidal mode are obtained analytically for the case with the substrate modulus decaying exponentially. The rigorous finite element analysis (FEA) is performed to validate the analytical model and investigate the postbuckling behaviour of the system. The critical buckling strain for the period-doubling mode is obtained numerically. The influences of various material parameters on the results are investigated. These results are helpful to provide physical insights on the buckling of elastic graded substrate-supported thin film.

Postbuckling analysis of ultra-low rigidity serpentine structures

2022 ◽  
pp. 1-18
Author(s):  
Jianzhong Zhao
Keyword(s):  
Analytical Model ◽  
Three Dimensional ◽  
Biological Tissues ◽  
Stretchable Electronics ◽  
Arbitrary Geometry ◽  
Material Parameters ◽  
Mechanical And Physical Properties ◽  
3D Assembly ◽  
Mechanical Sensing ◽  
Analytical Expressions

Abstract Serpentine structures are of growing interest due to its unique mechanical and physical properties for applications in stretchable electronics, mechanical sensing, biomedical devices. Mechanics-guided, deterministic three-dimensional (3D) assembly provide routes to form remarkable 3D structures, which in turn significantly improve its potential for applications. Therefore, an accurate postbuckling analysis is essential to the complex 3D serpentine structures with arbitrary geometry/material parameters. Here, simple, analytical expressions are obtained for the displacement and effective rigidity of serpentine structures during postbuckling. By tuning geometry parameters, the amplitude of assembled 3D serpentine structures can span a very broad range from zero to that of a straight ribbon. The analytical model can be used in design, fabrication, and application of versatile 3D serpentine structures to ensure their compatibility with the ultra-low rigidity biological tissues. A hierarchical 3D serpentine structure with ultra-low rigidity is presented to demonstrate the application of the analytical model.

scholarly journals Wrinkling of a stiff thin film bonded to a pre-strained, compliant substrate with finite thickness

2016 ◽  
Vol 472 (2192) ◽  
pp. 20160339 ◽  
Author(s):  
Yinji Ma ◽  
Yeguang Xue ◽  
Kyung-In Jang ◽  
Xue Feng ◽  
John A. Rogers ◽  
...  
Keyword(s):  
Thin Film ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Finite Thickness ◽  
Analytical Models ◽  
Thickness Effect ◽  
Element Analysis ◽  
Compliant Substrate ◽  
Tensile Stiffness ◽  
The Finite Element Analysis

A stiff thin film bonded to a pre-strained, compliant substrate wrinkles into a sinusoidal form upon release of the pre-strain. Many analytical models developed for the critical pre-strain for wrinkling assume that the substrate is semi-infinite. This critical pre-strain is actually much smaller than that for a substrate with finite thickness (Ma Y et al. 2016 Adv. Funct. Mater. ( doi:10.1002/adfm.201600713 )). An analytical solution of the critical pre-strain for a system of a stiff film bonded to a pre-strained, finite-thickness, compliant substrate is obtained, and it agrees well with the finite-element analysis. The finite-thickness effect is significant when the substrate tensile stiffness cannot overwhelm the film tensile stiffness.

Vibration characteristics of island-bridge structure on porous PDMS substrates for stretchable electronics

2021 ◽  
pp. 1-18
Author(s):  
Xin Song ◽  
Zuguang Bian ◽  
Xiaoliang Zhou ◽  
Zhuye Huang
Keyword(s):  
Analytical Model ◽  
Mechanical Design ◽  
Dynamic Performance ◽  
Structure Design ◽  
Vibration Characteristics ◽  
Mode Shapes ◽  
Stretchable Electronics ◽  
Bridge Structure ◽  
Element Analysis ◽  
Design And Optimization

Abstract Stretchable electronics employing island-bridge structure design can achieve controllable and reversible stretchability. The use of a porous substrate, which provides excellent breathability for wearable devices bonded to skin, not only satisfies this static superiority but also has a profound impact on the dynamic performance of the stretchable electronics. In this paper, the vibration characteristics of the island-bridge structure based on porous polydimethylsiloxane (p-PDMS) substrates are studied by utilizing an analytical model, which takes account of geometric nonlinearity due to mid-plane stretching, buckling configuration, elastic boundary conditions considering the p-PDMS substrates and the mass of the island. In numerical examples, the accuracy of the analytical model is first verified by finite element analysis (FEA). After that, we investigate the effects of some primary factors, i.e. the prestrain of the substrate, spring stiffnesses at the ends of the interconnect, porosity and thickness of the substrate, and the mass of the island, on the natural frequencies and vibration mode shapes of the island-bridge structure. Results show that the vibration characteristics of the island-bridge structure can be tuned conveniently by adjusting the porosity of the substrate and the mass of the island, which are expected to be helpful to mechanical design and optimization of stretchable electronics in complex noise environments.

scholarly journals A Nonlinear Mechanics Model of Zigzag Cellular Substrates for Stretchable Electronics

2020 ◽  
Vol 87 (6) ◽  
Author(s):  
Shiwei Zhao ◽  
Feng Zhu ◽  
Zhengang Yan ◽  
Daochun Li ◽  
Jinwu Xiang ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Analytical Model ◽  
Strain Curve ◽  
Stretchable Electronics ◽  
Electronic Systems ◽  
Stress Strain Curve ◽  
Element Analysis ◽  
Natural Motion ◽  
Mechanics Model ◽  
Nonlinear Stress

Abstract The use of cellular elastomer substrates not only reduces its restriction on natural diffusion or convection of biofluids in the realm of stretchable electronics but also enhances the stretchability of the electronic systems. An analytical model of “zigzag” cellular substrates under finite deformation is established and validated in this paper. The deformed shape, nonlinear stress–strain curve, and Poisson’s ratio–strain curve of the cellular elastomer substrate calculated using the reported analytical model agree well with those from finite element analysis (FEA). Results show that lower restriction on the natural motion of human skin could be achieved by the proposed zigzag cellular substrates compared with the previously reported hexagonal cellular substrates, manifesting another leap toward mechanically “invisible” wearable, stretchable electronic systems.

Lifetime Prediction of Tires with Regard to Oxidative Aging5

2008 ◽  
Vol 36 (1) ◽  
pp. 63-79 ◽  
Author(s):  
L. Nasdala ◽  
Y. Wei ◽  
H. Rothert ◽  
M. Kaliske
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Temperature Distribution ◽  
Superposition Principle ◽  
Accelerated Aging ◽  
Material Model ◽  
Aging Behavior ◽  
Element Analysis ◽  
Material Parameters ◽  
Reaction Processes

Abstract It is a challenging task in the design of automobile tires to predict lifetime and performance on the basis of numerical simulations. Several factors have to be taken into account to correctly estimate the aging behavior. This paper focuses on oxygen reaction processes which, apart from mechanical and thermal aspects, effect the tire durability. The material parameters needed to describe the temperature-dependent oxygen diffusion and reaction processes are derived by means of the time–temperature–superposition principle from modulus profiling tests. These experiments are designed to examine the diffusion-limited oxidation (DLO) effect which occurs when accelerated aging tests are performed. For the cord-reinforced rubber composites, homogenization techniques are adopted to obtain effective material parameters (diffusivities and reaction constants). The selection and arrangement of rubber components influence the temperature distribution and the oxygen penetration depth which impact tire durability. The goal of this paper is to establish a finite element analysis based criterion to predict lifetime with respect to oxidative aging. The finite element analysis is carried out in three stages. First the heat generation rate distribution is calculated using a viscoelastic material model. Then the temperature distribution can be determined. In the third step we evaluate the oxygen distribution or rather the oxygen consumption rate, which is a measure for the tire lifetime. Thus, the aging behavior of different kinds of tires can be compared. Numerical examples show how diffusivities, reaction coefficients, and temperature influence the durability of different tire parts. It is found that due to the DLO effect, some interior parts may age slower even if the temperature is increased.

Evaluation of web reinforcements in prestressed concrete box girders through shear-transverse bending domains

2020 ◽  
pp. 136943322098170
Author(s):  
Michele Fabio Granata ◽  
Antonino Recupero
Keyword(s):  
Analytical Model ◽  
Prestressed Concrete ◽  
3D Analysis ◽  
Box Girders ◽  
Element Analysis ◽  
Cross Sectional ◽  
Interaction Domains ◽  
Global And Local ◽  
Resultant Forces

In concrete box girders, the amount and distribution of reinforcements in the webs have to be estimated considering the local effects due to eccentric external loads and cross-sectional distortion and not only the global effect due to the resultant forces of a longitudinal analysis: shear, torsion and bending. This work presents an analytical model that allows designers to take into account the interaction of all these effects, global and local, for the determination of the reinforcements. The model is based on the theory of stress fields and it has been compared to a 3D finite element analysis, in order to validate the interaction domains. The results show how the proposed analytical model allows an easy and reliable reinforcement evaluation, in agreement with a more refined 3D analysis but with a reduced computational burden.

Analytical model and temperature dependence of the thin film SOI FET

1995 ◽  
Vol 38 (5) ◽  
pp. 949-959 ◽  
Author(s):  
S Scheinert ◽  
G Paasch ◽  
D Schipanski
Keyword(s):  
Thin Film ◽  
Temperature Dependence ◽  
Analytical Model

An analytical model for the above-threshold characteristics of polysilicon thin-film transistors

1995 ◽  
Vol 42 (7) ◽  
pp. 1240-1246 ◽  
Author(s):  
Horng Nan Chern ◽  
Chung Len Lee ◽  
Tan Fu Lei
Keyword(s):  
Thin Film ◽  
Analytical Model ◽  
Thin Film Transistors

A Finite Element Analysis for Magnetostrictive Thin Film Structures and Its Experimental Verification

2006 ◽  
Vol 306-308 ◽  
pp. 1151-1156 ◽  
Author(s):  
Chong Du Cho ◽  
Heung Shik Lee ◽  
Chang Boo Kim ◽  
Hyeon Gyu Beom
Keyword(s):  
Thin Film ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Geometric Feature ◽  
Hysteresis Phenomenon ◽  
Finite Element Code ◽  
Element Analysis ◽  
Element Mesh ◽  
Magnetostrictive Actuators ◽  
Large Length

In this paper, a finite element code especially for micro-magnetostrictive actuators was developed. Two significant characteristics of the presented finite element code are: (1) the magnetostrictive hysteresis phenomenon is effectively taken into account; (2) intrinsic geometric feature of typical thin film structures of large length to thickness ratio, which makes it very difficult to construct finite element mesh in the region of the thin film, is considered reasonably in modeling micro-magneostrictive actuators. For verification purpose, magnetostrictive thin films were fabricated and tested in the form of a cantilevered actuator. The Tb-Fe film and Sm-Fe film are sputtered on the Si and Polyimide substrates individually. The magnetic and magnetostrictive properties of the sputtered magnetostrictive films are measured. The measured magnetostrictive coefficients are compared with the numerically calculated ones.

An Interfacial Delamination Analysis for Multichip Module Thin Film Interconnects

1996 ◽  
Vol 118 (4) ◽  
pp. 206-213 ◽  
Author(s):  
K. X. Hu ◽  
C. P. Yeh ◽  
X. S. Wu ◽  
K. Wyatt
Keyword(s):  
Thin Film ◽  
Phase Angle ◽  
Structural Reliability ◽  
Thermal Loading ◽  
Multichip Module ◽  
Crack Model ◽  
Element Analysis ◽  
Delamination Growth ◽  
Interfacial Delamination ◽  
Functional Behavior

Analysis of interfacial delamination for multichip module thin-film interconnects (MCM/TFI) is the primary objective of this paper. An interface crack model is integrated with finite-element analysis to allow for accurate numerical evaluation of the magnitude and phase angle of the complex stress intensity factor. Under the assumption of quasi-static delamination growth, the fate of an interfacial delamination after inception of propagation is determined. It is established that whether an interfacial delamination will continue to grow or become arrested depends on the functional behavior of the energy release rate and loading phase angle over the history of delamination growth. This functional behavior is numerically obtained for a typical MCM/TFI structure with delamination along die and via base, subjected to thermal loading condition. The effect of delamination interactions on the structural reliability is also investigated. It is observed that the delamination along via wall and polymer thin film can provide a benevolent mechanism to relieve thermal constraints, leading to via stress relaxation.

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