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Article
Publication date: 2 October 2009

Weigang Cui, Xin Wang, Wenbin Li and Weilin Xu

The purpose of this paper is to present a dynamic analysis on the thermal and electrical properties of fabrics under wet conditions.

Abstract

Purpose

The purpose of this paper is to present a dynamic analysis on the thermal and electrical properties of fabrics under wet conditions.

Design/methodology/approach

A purpose‐built apparatus is applied to test the thermal and electrical properties of textiles in moisture absorption and liberation process. Relation between temperature and resistance of a cotton/polyester double‐layer fabric is also analysed.

Findings

The surface temperature of textiles shows three different stages in the process. The electrical resistance is linearly related to the reciprocal of the moisture regain of fabrics. In the moisture absorption and liberation process, surface temperature of cotton layer is higher than that of polyester layer. And the electrical resistance of cotton layer decreases more quickly than that of polyester layer. The electrical resistance changes earlier than surface temperature in the moisture‐liberation process.

Practical implications

The paper is helpful in not only the designing of sportswear, but also the devising of moisture‐testing apparatus.

Originality/value

A dynamic testing method is applied to characterize the thermal and electrical properties of textiles.

Details

International Journal of Clothing Science and Technology, vol. 21 no. 5
Type: Research Article
ISSN: 0955-6222

Keywords

Open Access
Article
Publication date: 5 November 2021

Darko Lovrec and Vito Tič

Apart from the basic material properties of liquid lubricants, such as, e.g., the viscosity and density of the hydraulic fluid, it is also important to have information…

Abstract

Purpose

Apart from the basic material properties of liquid lubricants, such as, e.g., the viscosity and density of the hydraulic fluid, it is also important to have information regarding the electrical properties of the fluid used. The latter is closely related to the purpose, type, structure, and conditions of use of a hydraulic system, especially the powertrain design and fluid condition monitoring. The insulating capacity of the hydraulic fluid is important in cases where the electric motor of the pump is immersed in the fluid. In other cases, on the basis of changing the electrical conductive properties of the hydraulic fluid, we can refer its condition, and, on this basis, the degree of degradation.

Design/methodology/approach

The paper first highlights the importance of knowing the electrical properties of hydraulic fluids and then aims to compare these properties, such as the breakdown voltage of commonly used hydraulic mineral oils and newer ionic fluids suitable for use as hydraulic fluids.

Findings

Knowledge of this property is crucial for the design approach of modern hydraulic compact power packs. In the following, the emphasis is on the more advanced use of known electrical quantities, such as electrical conductivity and the dielectric constant of a liquid.

Originality/value

Based on the changes in these quantities, we have the possibility of real-time monitoring the hydraulic fluid condition, on the basis of which we judge the degree of fluid degradation and its suitability for further use.

Details

Industrial Lubrication and Tribology, vol. 74 no. 3
Type: Research Article
ISSN: 0036-8792

Keywords

Article
Publication date: 14 November 2008

A. Belahcen and A. Arkkio

The purpose of this paper is to find out how to model the effect of mechanical stresses on the magnetic properties of electrical steel used in electromagnetic devices and…

Abstract

Purpose

The purpose of this paper is to find out how to model the effect of mechanical stresses on the magnetic properties of electrical steel used in electromagnetic devices and especially in electrical machines. Further, the effect of these stresses on the operation of the machines should be studied.

Design/methodology/approach

The constitutive equation of the electrical steel is usually modeled as a non linear relation between the magnetic flux density and the magnetic field strength. In this research, this constitutive equation is developed to account for the mechanical stresses through a parametric relationship, the parameters of which are estimated from measurements. Further, the constitutive equation is used in a magnetomechanically coupled numerical simulation of an induction machine.

Findings

The mechanical stresses degrade the properties of the electrical steel and increase the magnetization current in electrical machines. This leads to a decrease in the efficiency of these machines.

Research limitations/implications

The effect of mechanical stresses is studied from the point of view of magnetization properties. This work does not model the effect of stresses on the specific losses of the material. Such a research is still going on.

Originality/value

The effect of mechanical stress on the magnetic properties of the materials used in electrical machines is modeled in an easy and original way, which allow for its application in numerical simulation and analysis of these machines.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 27 no. 6
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 1 January 2014

Haibao Lu, Yongtao Yao and Long Lin

This article aims to present a systematic and up-to-date account of carbon-based reinforcements, including carbon nanotube (CNT), carbon nanofibre (CNF), carbon black…

1589

Abstract

Purpose

This article aims to present a systematic and up-to-date account of carbon-based reinforcements, including carbon nanotube (CNT), carbon nanofibre (CNF), carbon black (CB), carbon fibre (CF) and grapheme, in shape-memory polymer (SMP) for electrical actuation.

Design/methodology/approach

Studies exploring carbon-based reinforcement in SMP composites for electrically conductive performance and Joule heating triggered shape recovery have been included, especially for the principle design, characterisation and shape recovery behaviour, making the article a comprehensive account of the systemic progress in SMP composite incorporating conductive carbon reinforcement.

Findings

SMPs are fascinating materials and have attracted great academic and industrial attention owing to their significant macroscopic shape deformation in the presence of an appropriate stimulus. The working mechanisms, the physico requirements and the theoretical origins of the different types of carbon-based reinforcement SMP composites have been discussed. Current research and development on the fabrication strategies of carbon-based reinforcement SMP composites have been summarised.

Research limitations/implications

A systematic review is to evaluate carbon-based reinforcements in SMPs for electrical actuation and discuss recent developments and future applications.

Practical implications

Carbon-based reinforcements in SMPs can be used as smart deployable space structure in the broad field of aerospace technologies.

Originality/value

To reveal the research and development of utilising CNT, CNF, CB, CF and grapheme to achieve shape recovery of SMP composites through electrically resistive heating, which will significantly benefit the research and development of smart materials and systems.

Details

Pigment & Resin Technology, vol. 43 no. 1
Type: Research Article
ISSN: 0369-9420

Keywords

Article
Publication date: 2 April 2020

Delfim Soares, Manuel Sarmento, Daniel Barros, Helder Peixoto, Hugo Figueiredo, Ricardo Alves, Isabel Delgado, José C. Teixeira and Fátima Cerqueira

This study aims to investigate the effect of bismuth addition (up to 30 Wt%) on the microstructure and electrical conductivity of a commercial lead-free alloy (SAC405…

Abstract

Purpose

This study aims to investigate the effect of bismuth addition (up to 30 Wt%) on the microstructure and electrical conductivity of a commercial lead-free alloy (SAC405) near the solder/substrate soldered joint. The system under study is referred in this work as (SAC405 + xBi)/Cu, as Cu is the selected substrate in which the solder was casted. The electrical resistivity of this system was investigated, considering Bi addition effect on the local microstructure and chemical composition gradients within that zone.

Design/methodology/approach

Solder joints between Cu substrate and SAC405 alloy with different levels of Bi were produced. The electrical conductivity along the obtained solder/substrate interface was measured by four-point probe method. The microstructure and chemical compositions were evaluated by scanning electron microscopy/energy dispersive spectroscopy analysis.

Findings

Two different electrical resistivity zones were identified within the solder interface copper substrate/solder alloy. At the first zone (from intermetallic compound [IMC] until approximately 100 μm) the increase of the electrical resistivity is gradual from the substrate to the solder side. This is because of the copper substrate diffusion, which established a chemical composition gradient near the IMC layer. At the second zone, electrical resistivity becomes much higher and is mainly dependent on the Bi content of the solder alloy. In both identified zones, electrical resistivity is affected by its microstructure, which is dependent on Cu and Bi content and solidification characteristics.

Originality/value

A detailed characterization of the solder/substrate zone, in terms of electrical conductivity, was done with the definition of two variation zones. With this knowledge, a better definition of processing parameters and in-service soldered electronic devices behavior can be achieved.

Details

Soldering & Surface Mount Technology, vol. 33 no. 1
Type: Research Article
ISSN: 0954-0911

Keywords

Article
Publication date: 5 January 2022

Thejas Ramakrishnaiah, Prasanna Gunderi Dhananjaya, Chaturmukha Vakwadi Sainagesh, Sathish Reddy, Swaroop Kumaraswamy and Naveen Chikkahanumajja Surendranatha

This paper aims to study the various developments taking place in the field of gas sensors made from polyaniline (PANI) nanocomposites, which leads to the development of…

Abstract

Purpose

This paper aims to study the various developments taking place in the field of gas sensors made from polyaniline (PANI) nanocomposites, which leads to the development of high-performance electrical and gas sensing materials operating at room temperature.

Design/methodology/approach

PANI/ferrite nanocomposites exhibit good electrical properties with lower dielectric losses. There are numerous reports on PANI and ferrite nanomaterial-based gas sensors which have good sensing response, feasible to operate at room temperature, requires less power and cost-effective.

Findings

This paper provides an overview of electrical and gas sensing properties of PANI/ferrite nanocomposites having improved selectivity, long-term stability and other sensing performance of sensors at room temperature.

Originality/value

The main purpose of this review paper is to focus on PANI/ferrite nanocomposite-based gas sensors operating at room temperature.

Details

Sensor Review, vol. 42 no. 1
Type: Research Article
ISSN: 0260-2288

Keywords

Article
Publication date: 13 September 2022

Modupeola Dada, Patricia Popoola, Ntombi Mathe, Sisa Pityana and Samson Adeosun

In this study, AlCoCrFeNi–Cu (Cu-based) and AlCoCrFeNi–Ti (Ti-based) high entropy alloys (HEAs) were fabricated using a direct blown powder technique via laser additive…

Abstract

Purpose

In this study, AlCoCrFeNi–Cu (Cu-based) and AlCoCrFeNi–Ti (Ti-based) high entropy alloys (HEAs) were fabricated using a direct blown powder technique via laser additive manufacturing on an A301 steel baseplate for aerospace applications. The purpose of this research is to investigate the electrical resistivity and oxidation behavior of the as-built copper (Cu)- and titanium (Ti)-based alloys and to understand the alloying effect, the HEAs core effects and the influence of laser parameters on the physical properties of the alloys.

Design/methodology/approach

The as-received AlCoCrFeNiCu and AlCoCrFeNiTi powders were used to fabricate HEA clads on an A301 steel baseplate preheated at 400°C using a 3 kW Rofin Sinar dY044 continuous-wave laser-deposition system fitted with a KUKA robotic arm. The deposits were sectioned using an electric cutting machine and prepared by standard metallographic methods to investigate the electrical and oxidation properties of the alloys.

Findings

The results showed that the laser power had the most influence on the physical properties of the alloys. The Ti-based alloy had better resistivity than the Cu-based alloy, whereas the Cu-based alloy had better oxidation residence than the Ti-based alloy which attributed to the compositional alloying effect (Cu, aluminum and nickel) and the orderliness of the lattice, which is significantly associated with the electron transportation; consequently, the more distorted the lattice, the easier the transportation of electrons and the better the properties of the HEAs.

Originality/value

It is evident from the studies that the composition of HEAs and the laser processing parameters are two significant factors that influence the physical properties of laser deposited HEAs for aerospace applications.

Details

World Journal of Engineering, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 1708-5284

Keywords

Article
Publication date: 7 June 2019

Lucja Dybowska-Sarapuk, Daniel Janczak, Bartlomiej Podsiadly, Malgorzata Jakubowska and Marcin Sloma

A comparison of electric and viscosity percolation threshold is crucial from the scientific and technical points of view to understand the features and capabilities of…

Abstract

Purpose

A comparison of electric and viscosity percolation threshold is crucial from the scientific and technical points of view to understand the features and capabilities of heterogeneous graphene composite materials and properly select the functional phase volume. Therefore, the purpose of this paper is to present the analysis of the electrical and rheological percolation thresholds in the polymer–graphene screen printing pastes and the analysis of the relation between these two parameters.

Design/methodology/approach

In the paper, the properties of polymer-based pastes with graphene nanoplatelets were tested: paste viscosity and printed layers conductivity. The tests of pastes with different filler content allowed to determine both the electrical and rheological percolation thresholds using power law, according to Kirkpatrick’s percolation model.

Findings

The electrical percolation threshold for graphene nanoplatelets (GNPs) in the composite was 0.74 Vol.% when the rheological percolation threshold is observed to be at 1.00 Vol.% of nanoplatelets. The percolation threshold values calculated using the Kirkpatrick’s percolation model were 0.87 and 0.5 Vol.% of GNPs in the paste for electrical and rheological percolation thresholds, respectively.

Originality/value

Recently, GNPs are becoming more popular as the material of the functional phase in screen printing heterophase materials, because of their unique mechanical and electrical properties. However, till date no research presented in the literature is related to the direct comparison of both the electrical and rheological percolation thresholds. Such analysis is important for the optimization of the printing process toward the highest quality of printed conductive paths, and finally the best electrical properties.

Details

Circuit World, vol. 45 no. 1
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 8 May 2009

Edward Miś, Andrzej Dziedzic and Karol Nitsch

A capacitor is a basic electronic passive component. Thick‐film technology allows manufacturing of capacitors covering the range of small and medium capacitances and they…

Abstract

Purpose

A capacitor is a basic electronic passive component. Thick‐film technology allows manufacturing of capacitors covering the range of small and medium capacitances and they have been investigated in depth already. Low temperature co‐fired ceramics (LTCC) technology makes it possible to fabricate buried capacitors, which leads to increased packaging density, but such components’ properties are not well known. The purpose of this paper is to present the results of investigations on thick‐film and LTCC capacitors made in various technological variants.

Design/methodology/approach

Thick‐film and LTCC capacitors were made in various technological variants. Different capacitor inks, metallurgy of electrodes and component constructions were investigated. Basic electrical properties and stability were determined. An electrical equivalent circuit of such components was developed based on frequency and temperature characteristics.

Findings

Simple electrical equivalent circuits of self‐made thick‐film and LTCC micro‐capacitors were developed based on measurements in frequency and temperature domain. Good fitting accuracy was obtained. The bulk material section of model is predominant in the low‐frequency range. Interface region and serial resistance influence are revealed at higher frequency, affecting mainly dissipation factor value. Also, temperature and thermal ageing have affected strongly on that part of the model.

Originality/value

The paper usefully examines the electrical properties and electrical equivalent models of thick‐film and LTCC micro‐capacitors.

Details

Microelectronics International, vol. 26 no. 2
Type: Research Article
ISSN: 1356-5362

Keywords

Article
Publication date: 8 March 2022

Jared Allison, John Pearce, Joseph Beaman and Carolyn Seepersad

Recent work has demonstrated the possibility of selectively sintering polymer powders with radio frequency (RF) radiation as a means of rapid, volumetric additive…

Abstract

Purpose

Recent work has demonstrated the possibility of selectively sintering polymer powders with radio frequency (RF) radiation as a means of rapid, volumetric additive manufacturing. Although RF radiation can be used as a volumetric energy source, non-uniform heating resulting from the sample geometry and electrode configuration can lead to adverse effects in RF-treated samples. This paper aims to address these heating uniformity issues by implementing a computational design strategy for doped polymer powder beds to improve the RF heating uniformity.

Design/methodology/approach

Two approaches for improving the RF heating uniformity are presented with the goal of developing an RF-assisted additive manufacturing process. Both techniques use COMSOL Multiphysics® to predict the temperature rise during simulated RF exposure for different geometries. The effectiveness of each approach is evaluated by calculating the uniformity index, which provides an objective metric for comparing the heating uniformity between simulations. The first method implements an iterative heuristic tuning strategy to functionally grade the electrical conductivity within the sample. The second method involves reorienting the electrodes during the heating stage such that the electric field is applied in two directions.

Findings

Both approaches are shown to improve the heating uniformity and predicted part geometry for several test cases when applied independently. However, the greatest improvement in heating uniformity is demonstrated by combining the approaches and using multiple electrode orientations while functionally grading the samples.

Originality/value

This work presents an innovative approach for overcoming RF heating uniformity issues to improve the resulting part geometry in an RF-assisted, volumetric additive manufacturing method.

Details

Rapid Prototyping Journal, vol. 28 no. 8
Type: Research Article
ISSN: 1355-2546

Keywords

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