scholarly journals A widely adaptable analytical method for thermal analysis of flexible electronics with complex heat source structures

2019 ◽  
Vol 475 (2228) ◽  
pp. 20190402 ◽  
Author(s):  
Yafei Yin ◽  
Min Li ◽  
Wei Yuan ◽  
Xiaolian Chen ◽  
Yuhang Li
Keyword(s):  
Heat Source ◽  
Thermal Management ◽  
Flexible Electronics ◽  
Analytical Method ◽  
Thermal Field ◽  
Complex Shape ◽  
Source Region ◽  
Electronic Devices ◽  
Crucial Issue ◽  
Element Analysis

Flexible electronics, as a relatively new category of device, exhibit prodigious potential in many applications, especially in bio-integrated fields. It is critical to understand that thermal management of certain kinds of exothermic flexible electronics is a crucial issue, whether to avoid or to take advantage of the excessive temperature. A widely adaptable analytical method, validated by finite-element analysis and experiments, is conducted to investigate the thermal properties of exothermic flexible electronics with a heat source in complex shape or complex array layout. The main theoretical strategy to obtain the thermal field is through an integral along the complex curve source region. The results predicted by the analytical model enable accurate control of temperature and heat flow in the flexible electronics, which may help in the design and fabrication of flexible electronic devices in the future.

scholarly journals Mathematical modeling of heat-trapping properties of a developed radiator surface in mechanical engineering

2021 ◽  
Vol 273 ◽  
pp. 07018
Author(s):  
Nikolay Chernov ◽  
Alexander Palii ◽  
Larisa Tolmacheva ◽  
Konstantin Tomilin ◽  
Mikhail Kritskiy
Keyword(s):  
Thermal Field ◽  
Electronic Devices ◽  
Complex Problem ◽  
Heat Extraction ◽  
Program System ◽  
Element Analysis ◽  
Physical Volume ◽  
Extended Surfaces ◽  
Reliability Of Operation ◽  
A Current

In this work the research of heat-removing properties of areas of extended surfaces, for example, of finned and needle radiators for assessment of efficiency of distribution of a thermal field and heat extraction is described. Also the description of the carried-out computational modeling is provided in the Fluent processor of universal program system of the final and element analysis Ansys. The relevance of the selected subject is confirmed by the fact that one of the most important and difficult tasks arising when developing the electronic equipment is a withdrawal of heat generated by it. At a current steady trend in reduction of dimensions of electronic devices this problem does not disappear, and opposite, becomes more and more sharp, and that is stronger, than device high power less its physical volume, and not only the efficiency of heat extraction, but also dimensions and, of course, reliability of operation of electronic devices depends on constructions of heat-removing elements. In work the conclusion is drawn that for a solution of a complex problem of assessment of efficiency of the heat sink for the purpose of decrease in temperature of heatterminated element, it is necessary to use electrothermal analogy.

Theoretical Modeling of Conformal Criterion for Flexible Electronics Attached onto Complex Surface

2021 ◽  
pp. 1-10
Author(s):  
Lin Xiao ◽  
Ming Cheng ◽  
Furong Chen ◽  
Shan Jiang ◽  
YongAn Huang
Keyword(s):  
Flexible Electronics ◽  
High Performance ◽  
Electronic Devices ◽  
Target Surface ◽  
Complex Surface ◽  
Rigid Sphere ◽  
Principal Curvatures ◽  
Element Analysis ◽  
Mechanics Model ◽  
Conformal Contact

Abstract Transferring completed electronic devices onto curvilinear surfaces is popular for fabricating three-dimensional curvilinear electronics with high performance, while the problem of conformality between the unstretchable devices and the surfaces needs to be considered. Prior conformability design based on conformal mechanics model is a feasible way to reduce the non-conformal contact. Former studies mainly focused on stretchable film electronics conforming onto soft bio-tissue with a sinusoidal form microscopic morphology or unstretchable film conforming onto rigid sphere substrate, which limits its applicability in the aspect of shape and modulus of the substrate. Here, a conformal mechanics model with general geometric shape and material is introduced by choosing a bicurvature surface as the target surface, and the conformal contact behavior of film electronics is analyzed. All eight fundamental local surface features is obtained by adjusting two principal curvatures of the bicurvature surface, and the conformal performance is simulated. A dimensionless conformal criterion is given by minimizing the total energy as a function of seven dimensionless parameters, including four in geometric and three in material. The model and analysis results are verified by the finite element analysis, and it can provide a guidance for prior conformability design of the curvilinear electronic devices during the planar manufacturing process.

scholarly journals Ag/VO2/Ag sandwich nylon film for smart thermal management and thermo-responsive electrical conductivity

2021 ◽  
pp. 152808372098654
Author(s):  
Linghui Peng ◽  
Lingling Shen ◽  
Weiren Fan ◽  
Zichuan Liu ◽  
Hongbo Qiu ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Thermal Comfort ◽  
Thermal Management ◽  
Flexible Electronics ◽  
Sandwich Structure ◽  
Outdoor Thermal Comfort ◽  
Ir Radiation ◽  
Indoor Space ◽  
Layer Structures ◽  
Radiation Management

Due to the effects of climate changing, the importance of outdoor thermal comfort has been recognized, and has gained more and more research attentions. Unlike indoor space where air conditioning can be easily implemented, outdoor thermal comfort can only be achieved by localized thermal management. Using textile is a simple but energy-saving way to realize outdoor thermal comfort. Herein, we report the design of a smart thermal management film with the silver/vanadium dioxide/silver (Ag/VO2/Ag) sandwich structure prepared by one-dimensional (1 D) nanowires. It was found that the Ag/VO2/Ag sandwich film was able to lower the temperature by around 10 °C under intense infrared (IR) radiation. In addition, the Ag/VO2/Ag sandwich structure film showed a thermo-responsive electrical conductivity and an outstanding bending stability, due to network structure formed by nanowires. It was experimentally proved that this sandwich structure was superior to other layer structures in IR shielding performance and thermo-responsive electrical conductivity. The as-prepared Ag/VO2/Ag sandwich structure film has great potential for various applications such as wearable devices, flexible electronics, medical monitors and smart IR radiation management.

scholarly journals Image-based semi-multiscale finite element analysis using elastic subdomain homogenization

Meccanica ◽  
2021 ◽  
Author(s):  
J. Jansson ◽  
K. Salomonsson ◽  
J. Olofsson
Keyword(s):  
Finite Element ◽  
Analytical Method ◽  
Effective Properties ◽  
Reference Model ◽  
Computational Time ◽  
Component Level ◽  
Element Analysis ◽  
Model Fidelity ◽  
Multiscale Finite Element ◽  
Anisotropic Elastic

AbstractIn this paper we present a semi-multiscale methodology, where a micrograph is split into multiple independent numerical model subdomains. The purpose of this approach is to enable a controlled reduction in model fidelity at the microscale, while providing more detailed material data for component level- or more advanced finite element models. The effective anisotropic elastic properties of each subdomain are computed using periodic boundary conditions, and are subsequently mapped back to a reduced mesh of the original micrograph. Alternatively, effective isotropic properties are generated using a semi-analytical method, based on averaged Hashin–Shtrikman bounds with fractions determined via pixel summation. The chosen discretization strategy (pixelwise or partially smoothed) is shown to introduce an uncertainty in effective properties lower than 2% for the edge-case of a finite plate containing a circular hole. The methodology is applied to a aluminium alloy micrograph. It is shown that the number of elements in the aluminium model can be reduced by $$99.89\%$$ 99.89 % while not deviating from the reference model effective material properties by more than $$0.65\%$$ 0.65 % , while also retaining some of the characteristics of the stress-field. The computational time of the semi-analytical method is shown to be several orders of magnitude lower than the numerical one.

Heat Transfer and Thermal Stress Analysis of an Optoelectronic Package

1991 ◽  
Vol 113 (3) ◽  
pp. 258-262 ◽  
Author(s):  
J. G. Stack ◽  
M. S. Acarlar
Keyword(s):  
Heat Transfer ◽  
Thermal Management ◽  
Power Dissipation ◽  
Point Of View ◽  
Optical Data ◽  
Data Link ◽  
Element Analysis ◽  
Thermally Induced ◽  
Temperature Changes ◽  
Induced Stresses

The reliability and life of an Optical Data Link transmitter are inversely related to the temperature of the LED. It is therefore critical to have efficient packaging from the point of view of thermal management. For the ODL® 200H devices, it is also necessary to ensure that all package seals remain hermetic throughout the stringent military temperature range requirements of −65 to +150°C. For these devices, finite element analysis was used to study both the thermal paths due to LED power dissipation and the thermally induced stresses in the hermetic joints due to ambient temperature changes

scholarly journals Sheet Resistance Measurements of Conductive Thin Films: A Comparison of Techniques

Electronics ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 960
Author(s):  
Mira Naftaly ◽  
Satyajit Das ◽  
John Gallop ◽  
Kewen Pan ◽  
Feras Alkhalil ◽  
...  
Keyword(s):  
Thin Films ◽  
Sheet Resistance ◽  
Flexible Electronics ◽  
Electronic Devices ◽  
Conductivity Measurements ◽  
Terahertz Time Domain Spectroscopy ◽  
Comparison Of Techniques ◽  
Terahertz Frequencies ◽  
Conductive Thin Films ◽  
Multiple Samples

Conductive thin films are an essential component of many electronic devices. Measuring their conductivity accurately is necessary for quality control and process monitoring. We compare conductivity measurements on films for flexible electronics using three different techniques: four-point probe, microwave resonator and terahertz time-domain spectroscopy. Multiple samples were examined, facilitating the comparison of the three techniques. Sheet resistance values at DC, microwave and terahertz frequencies were obtained and were found to be in close agreement.

Comparison of Buried Pipeline Crossing Assessments Using API RP 1102, Analytical Method and Finite Element Approach

2020 ◽  
Author(s):  
Nikhil Joshi ◽  
Pritha Ghosh ◽  
Jonathan Brewer ◽  
Lawrence Matta
Keyword(s):  
Finite Element ◽  
Analytical Method ◽  
Rapid Assessment ◽  
Buried Pipeline ◽  
The Finite Element Method ◽  
Buried Pipelines ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Element Approach ◽  
Multiple Loading

Abstract API RP 1102 provides a method to calculate stresses in buried pipelines due to surface loads resulting from the encroachment of roads and railroads. The API RP 1102 approach is commonly used in the industry, and widely available software allows for quick and easy implementation. However, the approach has several limitations on when it can be used, one of which is that it is limited to pipelines crossing as near to 90° (perpendicular crossing) as practicable. In no case can the crossing be less than 30° . In this paper, the stresses in the buried pipeline under standard highway vehicular loading calculated using the API RP 1102 method are compared with the results of two other methods; an analytical method that accounts for longitudinal and circumferential through wall bending effects, and the finite element method. The benefit of the alternate analytical method is that it is not subject to the limitations of API RP 1102 on crossing alignment or depth. However, this method is still subject to the limitation that the pipeline is straight and at a uniform depth. The fact that it is analytical in nature allows for rapid assessment of a number of pipes and load configurations. The finite element analysis using a 3D soil box approach offers the greatest flexibility in that pipes with bends or appurtenances can be assessed. However, this approach is time consuming and difficult to apply to multiple loading scenarios. Pipeline crossings between 0° (parallel) and 90° (perpendicular) are evaluated in the assessment reported here, even though these are beyond the scope of API RP 1102. A comparison across the three methods will provide a means to evaluate the level of conservatism, if any, in the API RP 1102 calculation for crossing between 30° and 90° . It also provides a rationale to evaluate whether the API RP 1102 calculation can potentially be extended for 0° (parallel) crossings.

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