scholarly journals Electrothermal Modeling and Analysis of Polypyrrole-Coated Wearable E-Textiles

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 550
Author(s):  
Akif Kaynak ◽  
Ali Zolfagharian ◽  
Toby Featherby ◽  
Mahdi Bodaghi ◽  
M. A. Parvez Mahmud ◽  
...  
Keyword(s):  
Finite Element ◽  
Plasma Treatment ◽  
Joule Heating ◽  
Electrical Resistance ◽  
Atmospheric Plasma ◽  
Maximum Temperature ◽  
Element Analysis ◽  
Numerical Work ◽  
Coated Fabrics ◽  
Fabric Surface

The inhomogeneity of the resistance of conducting polypyrrole-coated nylon–Lycra and polyester (PET) fabrics and its effects on surface temperature were investigated through a systematic experimental and numerical work including the optimization of coating conditions to determine the lowest resistivity conductive fabrics and establish a correlation between the fabrication conditions and the efficiency and uniformity of Joule heating in conductive textiles. For this purpose, the effects of plasma pre-treatment and molar concentration analysis of the dopant anthraquinone sulfonic acid (AQSA), oxidant ferric chloride, and monomer pyrrole was carried out to establish the conditions to determine the sample with the lowest electrical resistance for generating heat and model the experiments using the finite element modeling (FEM). Both PET and nylon-Lycra underwent atmospheric plasma treatment to functionalize the fabric surface to improve the binding of the polymer and obtain coatings with reduced resistance. Both fabrics were compared in terms of average electrical resistance for both plasma treated and untreated samples. The plasma treatment induced deep black coatings with lower resistance. Then, heat-generating experiments were conducted on the polypyrrole (PPy) coated fabrics with the lowest resistance using a variable power supply to study the distribution and maximum value of the temperature. The joule heating model was developed to predict the heating of the conductive fabrics via finite element analysis. The model was based on the measured electrical resistance at different zones of the coated fabrics. It was shown that, when the fabric was backed with neoprene insulation, it would heat up quicker and more evenly. The average electrical resistance of the PPy-PET sample used was 190 Ω, and a maximum temperature reading of 43 °C was recorded. The model results exhibited good agreement with thermal camera data.

Finite element analysis of vertical micro-probe considering Joule-heating effect

2017 ◽  
Vol 101 ◽  
pp. 96-105 ◽  
Author(s):  
Hyun-Woo Jung ◽  
Seung-Jae Kim ◽  
Yun-Jae Kim ◽  
Jung-Yup Kim ◽  
Joo-Yul Lee ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Joule Heating ◽  
Heating Effect ◽  
Element Analysis ◽  
Joule Heating Effect

Study on Thermal Placement Optimization of Embedded MCM

2011 ◽  
Vol 189-193 ◽  
pp. 2269-2273
Author(s):  
Chun Yue Huang ◽  
Tian Ming Li ◽  
Ying Liang ◽  
He Geng Wei
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Temperature Field ◽  
Field Distribution ◽  
Temperature Difference ◽  
Optimization Algorithm ◽  
Thermal Field ◽  
Maximum Temperature ◽  
Element Analysis ◽  
Placement Optimization

In the thermal design of embedded multi-chip module (MCM), the placement of chips has a significant effect on temperature field distributing, thus influences the reliability of the embedded MCM. The thermal placement optimization of chips in embedded MCM was studied in this paper, the goal of this work is to decrease temperature and achieve uniform thermal field distribution within embedded MCM. By using ANSYS the finite element analysis model of embedded MCM was developed, the temperature field distributing was calculated. Based on genetic algorithms, chips placement optimization algorithm of embedded MCM was proposed and the optimization chips placement of embedded MCM was achieved by corresponding optimization program. To demonstrate the effectiveness of the obtained optimization chips placement, finite element analysis (FEA) was carried out to assess the thermal field distribution of the optimization chips placement in embedded MCM by using ANSYS. The result shows that without chips placement optimizing the maximum temperature and temperature difference in embedded MCM model are 87.963°C and 2.189°C respectively, by using chips placement optimization algorithm the maximum temperature drop than the original 0.583°C and the temperature difference is only 0.694°C . It turns out that the chip placement optimization approach proposed in this work can be effective in providing thermal optimal design of chip placement in embedded MCM.

New Data on the Capacity of X-Joints Under Tension and Implications for Codes

2008 ◽  
Author(s):  
Adrian F. Dier ◽  
Philip Smedley ◽  
Gunnar Solland ◽  
Hege Bang
Keyword(s):  
Finite Element ◽  
Structural Integrity ◽  
Hot Spot ◽  
Case Scenario ◽  
Element Analysis ◽  
Worst Case ◽  
Numerical Work ◽  
Hot Spot Stress ◽  
Integrity Assessment ◽  
Existing Structures

This paper reviews available static strength data and presents results of finite element analyses on first crack loads and ultimate loads of X-joints in tension. A critique of existing guidance for such joints is given. An examination of hot spot stress for such joints is presented, together with new capacity formulations based on test data. The new formulations are verified with reference to new data from a finite element analysis. The new capacity formulations will be of interest to regulatory authorities, to designers of new offshore installations and to engineers carrying out assessments of existing structures. It is also expected that the formulations will be considered by code drafting committees, e.g. for API RP2A, ISO 19902 and NORSOK, during code revisions. The paper demonstrates that present guidance is unduly conservative in two respects: (1) high γ joints (i.e. thin-walled chords) in the range 0.7 ≤ β ≤ 0.9 joints (i.e. moderately high brace/chord diameter ratios), and (2) joints with β = 1.0 having low γ. However, it is shown that present guidance may be optimistic for low γ joints with β < 0.9. The new capacity formulations proposed in this paper correct these deficiencies. As one example, the new formulations give an increase of 60% in capacity compared to existing guidance for a joint with β = 1.0 and γ = 10, not untypical of many joints in service. In the near term, the paper may be most appreciated by those involved with structural integrity assessment studies. There have been some recent examples where existing guidance has indicated that some primary structural joints are under-strength. This has prompted extensive numerical work to prove the adequacy of the joints. A worst case scenario would be the implementation of unnecessary offshore strengthening work.

Joule Heating and Peltier Effects in Thermoelectric Spin-Transfer Torque Mram Devices Using Finite Element Modeling

2014 ◽  
Vol 931-932 ◽  
pp. 989-993 ◽  
Author(s):  
Supakorn Harnsoongnoen ◽  
N. Phaengpha ◽  
S. Ritjaroenwattu ◽  
U. Charoen-In ◽  
Apirat Siritaratiwat
Keyword(s):  
Heat Flux ◽  
Finite Element ◽  
Finite Element Modeling ◽  
Joule Heating ◽  
Tunnel Junction ◽  
Magnetic Tunnel Junction ◽  
Spin Transfer Torque ◽  
Spin Transfer ◽  
Maximum Temperature ◽  
Element Modeling

This paper reports the Joule heating and Peltier effects in thermoelectric spin-transfer torque MRAMs (TSTT-MRAMs). The simulation was undertaken based on the current-induced magnetization switching at the MgO/CoFe magnetic tunnel junction. Thermal and heat flux distributions of the TSTT-MRAM cells were simulated and analyzed using finite-element modeling. The Joule heating and Peltier effects lead to the increases in the temperature and heat flux distributions at the magnetic tunnel junction (MTJ) as well as the thermoelectric module. The maximum temperature of Peltier effect is higher than Joule heating effect when voltage amplitude below 0.77V. Some practical data for the STT-MRAM were also reported.

Temperature-Based Criteria for Opening Newly Laid Repaired Asphalt Pavement Sections to Traffic

2020 ◽  
Vol 2674 (3) ◽  
pp. 161-178
Author(s):  
L. He ◽  
L. Chu ◽  
T. F. Fwa
Keyword(s):  
Finite Element ◽  
Surface Temperature ◽  
Simulation Analysis ◽  
Asphalt Pavement ◽  
Weather Conditions ◽  
Air Traffic ◽  
Maximum Temperature ◽  
Element Analysis ◽  
Wind Speeds ◽  
Allowable Temperature

To avoid premature damage, a newly laid asphalt pavement repair must be allowed to cool sufficiently before opening to air traffic. This study examines the variations of temperature within different repaired asphalt layers during cooling, and makes recommendations with regard to the choice of temperature-based criteria for determining the earliest time to open a newly laid asphalt pavement section to air traffic in a busy airport. Using finite element simulation analysis, the cooling patterns of asphalt layers under the following conditions were studied: three different weather conditions (sunny daytime, cloudy daytime, and nighttime) with three different wind speeds. It is shown that the common practice of relying on surface temperature to determine the time for opening to traffic is unsatisfactory. This is because under most paving conditions, a large proportion of the newly laid asphalt layer would still have temperatures higher than the surface temperature. From finite element analysis for different paving and environmental conditions, it is recommended that the temperatures at an interior point be measured at either 1/2, 2/3, or 3/4 depth, and that nighttime paving be preferred. This study shows that for common asphalt pavement repairs of thicknesses up to 150 mm, taking the temperature at either 2/3 or 3/4 depth as the guide, a repaired asphalt layer, when opened to air traffic, would have its internal maximum temperature kept within 2°C of the preset maximum allowable temperature. If the 1/2 depth temperature is selected as a guide, a margin of within 4°C of the preset maximum allowable temperature can be achieved.

A Compact Approach to On-Chip Interconnect Heat Conduction Modeling Using the Finite Element Method

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
Siva P. Gurrum ◽  
Yogendra K. Joshi ◽  
William P. King ◽  
Koneru Ramakrishna ◽  
Martin Gall
Keyword(s):  
Finite Element ◽  
Joule Heating ◽  
Temperature Rise ◽  
Signal Propagation ◽  
Compact Model ◽  
Computational Time ◽  
Maximum Temperature ◽  
Clock Signal ◽  
Current Densities ◽  
On Chip

Over upcoming electronics technology nodes, shrinking feature sizes of on-chip interconnects and correspondingly higher current densities are expected to result in higher temperatures due to self-heating. This study describes a finite element based compact thermal modeling approach to investigate the effects of Joule heating on complex interconnect structures. In this method, interconnect cross section is assumed to be isothermal and conduction along the interconnect is retained. A composite finite element containing both metal and dielectric regions is used to discretize the interconnect stack. The compact approach predicts the maximum temperature rise in the metal to within 5–10% of the detailed numerical computations, while requiring only a fraction of elements. Computational time for the compact model solution is several seconds, versus many hours for the detailed solutions obtained through successive mesh refinement until grid independence is achieved. For a comparable number of elements, the compact model is in general much more accurate than the traditional finite element approach. To validate the simulations, temperature rise in a 500-link two-layer interconnect with a via layer was measured at several current densities. The compact method predicts the temperature rise of the 500-link chain to within 5% of the measurements thereby validating the method. The approach described here could be an efficient technique for full chip Joule heating simulations and for clock signal propagation simulations, which are performed as part of designing next generation chip architectures.

scholarly journals 3D Thermal Finite Element Analysis of the SLM 316L Parts with Microstructural Correlations

Complexity ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Ketai He ◽  
Xue Zhao
Keyword(s):  
Finite Element ◽  
Temperature Field ◽  
Molten Pool ◽  
Steel Powder ◽  
Element Model ◽  
Maximum Temperature ◽  
Element Analysis ◽  
Measurement Results ◽  
Scanning Strategies ◽  
Maximum Temperature Gradient

In this study, a multitrack and multilayer finite element model was developed to simulate the temperature field and molten pool contours during selective laser melting (SLM) of 316L stainless steel powder under different scanning strategies. The simulated temperature field and its evolution over time were compared with experimental measurement results. Furthermore, a correlation was established by the presented results between the predicted thermal behavior and the microstructure of SLM specimens. It was found that the maximum temperature of the molten pool rose slightly with the increase of scanning tracks, but when laser scanned multilayer, the maximum temperature rose first and then decreased. There are large columnar crystals in molten pools, growing in the direction of the maximum temperature gradient. The microstructure defects are more likely to occur at the bonding regions between adjacent layers and islands, where the heat and stress are concentrated. Moreover, the results also showed that the scanning strategy affects the microstructure and microhardness. Also, the SLM 316L parts under the S-shaped strategy had finer grains and a higher Vicker hardness than that formed under the island strategy.

Electrical self-sensing of impact damage in multiscale hierarchical composites with tailored location of carbon nanotube networks

2018 ◽  
Vol 18 (3) ◽  
pp. 806-818 ◽  
Author(s):  
BKS Isaac-Medina ◽  
A Alonzo-García ◽  
F Avilés
Keyword(s):  
Carbon Nanotubes ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Electrical Resistance ◽  
Impact Damage ◽  
Multiwall Carbon Nanotubes ◽  
Element Analysis ◽  
The Matrix ◽  
Hierarchical Composites ◽  
Multiwall Carbon

Low-velocity impact damage in multiscale hierarchical composites comprising glass fiber weaves reinforcing a vinyl ester matrix with tailored location of multiwall carbon nanotubes is assessed through the changes of electrical resistance before and after impact. The location of the multiwall carbon nanotubes within the multiscale composite is controlled from manufacturing, rendering two hierarchical architectures. In the first one, as-received glass fiber weaves are used and the multiwall carbon nanotubes are only dispersed within the matrix, while in the second one the multiwall carbon nanotubes are dispersed within the matrix and also bonded to the glass fibers. Spatial electrical resistance maps are able to track the damage progression and growth of damage extension under consecutive impacts and the results are correlated to stresses determined by finite element analysis and ultrasonic C-scanning. The correlation between the electrical mapping and finite element analysis showed that the panels containing multiwall carbon nanotubes on the fiber are more sensitive to delamination and interfacial damage than the ones containing multiwall carbon nanotubes only dispersed within the polymer matrix.

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