Srinivas Naik Lonavath and Hadya Boda
This Friction stir welding study aims to weld thick AA8011 aluminium plates, and the interface joints created with a variety of tool pin profiles were examined for their effects…
Abstract
Purpose
This Friction stir welding study aims to weld thick AA8011 aluminium plates, and the interface joints created with a variety of tool pin profiles were examined for their effects on the welding process.
Design/methodology/approach
Scanning electron microscopy and optical microscopy and X-ray diffraction were used to examine the macro and micro-structural characteristics, as well as the fracture surfaces, of tensile specimens. The mechanical properties (tensile, hardness tests) of the base metal and the welded specimens under a variety of situations being tested. Additionally, a fracture toughness test was used to analyse the resilience of the base metal and the best weldments to crack formation. Using a response surface methodology with a Box–Behnken design, the optimum values for the three key parameters (rotational speed, welding speed and tool pin profile) positively affecting the weld quality were established.
Findings
The results demonstrate that a defect-free junction can be obtained by using a cylindrical tool pin profile, increasing the rotational speed while decreasing the welding speeds. The high temperature and compressive residual stress generated during welding leads to the increase in grain size. The grain size of the welded zone for optimal conditions is significantly smaller and the hardness of the stir zone is higher than the other experimental run parameters.
Originality/value
The work focuses on the careful examination of microstructures behaviour under various tool pin profile responsible for the change in mechanical properties. The mathematical model generated using Taguchi approach and parameters was optimized by using multi-objectives response surface methodology techniques.
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Xu Han, Xiaoyan Li, Peng Yao and Dalong Chen
This study aims to investigate the interfacial microstructures of ultrasonic-assisted solder joints at different soldering times.
Abstract
Purpose
This study aims to investigate the interfacial microstructures of ultrasonic-assisted solder joints at different soldering times.
Design/methodology/approach
Solder joints with different microstructures are obtained by ultrasonic-assisted soldering. To analyze the effect of ultrasounds on Cu6Sn5 growth during the solid–liquid reaction stage, the interconnection heights of solder joints are increased from 30 to 50 μm.
Findings
Scallop-like Cu6Sn5 nucleate and grow along the Cu6Sn5/Cu3Sn interface under the traditional soldering process. By comparison, some Cu6Sn5 are formed at Cu6Sn5/Cu3Sn interface and some Cu6Sn5 are randomly distributed in Sn when ultrasonic-assisted soldering process is used. The reason for the formation of non-interfacial Cu6Sn5 has to do with the shock waves and micro-jets produced by ultrasonic treatment, which leads to separation of some Cu6Sn5 from the interfacial Cu6Sn5 to form non-interfacial Cu6Sn5. The local high pressure generated by the ultrasounds promotes the heterogeneous nucleation and growth of Cu6Sn5. Also, some branch-like Cu3Sn formed at Cu6Sn5/Cu3Sn interface render the interfacial Cu3Sn in ultrasonic-assisted solder joints present a different morphology from the wave-like or planar-like Cu3Sn in conventional soldering joints. Meanwhile, some non-interfacial Cu3Sn are present in non-interfacial Cu6Sn5 due to reaction of Cu atoms in liquid Sn with non-interfacial Cu6Sn5 to form non-interfacial Cu3Sn. Overall, full Cu3Sn solder joints are obtained at ultrasonic times of 60 s.
Originality/value
The obtained microstructure evolutions of ultrasonic-assisted solder joints in this paper are different from those reported in previous studies. Based on these differences, the effects of ultrasounds on the formation of non-interfacial IMCs and growth of interfacial IMCs are systematically analyzed by comparing with the traditional soldering process.
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Gopalakrishnan Palaniappan, Anita Rachel D., Sentilkumar C.B., Selvaraj Senthil Kumar, Senthil Kumar B. and Devaki E.
Eri is a short-stapled fibre that possesses an excellent soft feel and warmness to the wearer. Investigation of thermal comfort and moisture properties of Eri silk fabric provides…
Abstract
Purpose
Eri is a short-stapled fibre that possesses an excellent soft feel and warmness to the wearer. Investigation of thermal comfort and moisture properties of Eri silk fabric provides the enhanced commercial scope for Eri silk-based clothing.
Design/methodology/approach
To examine the impact of process factors on thermal and moisture properties, three different single knit Eri silk structures were made, each with a different loop length and yarn count. Three different linear densities of Eri silk spun yarn (15, 20 and 25 tex) were selected. Three distinct knitted constructions, including plain jersey, popcorn and cellular blister, were created, along with two different loop lengths.
Findings
The novel cellular blister structure has shown appreciable thermal comfort properties than the other two structures. Yarn fineness and loop length were significant with most of the thermal comfort properties.
Research limitations/implications
In recent times the Eri silk production is completely domesticated, so the new demand can easily be met by the producers. This research will create a new scope for Eri silk fibres in sportswear and leisure wear.
Originality/value
This study was conducted to explore the influence of knit structure, loop length and yarn count on the thermal comfort properties of the clothing.
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Manikandamaharaj T.S. and Jaffar Ali B.M.
Effective performance of a direct ethanol fuel cell (FC) stack depends on the satisfactory operation of its individual cells where it is always challenging to manage the…
Abstract
Purpose
Effective performance of a direct ethanol fuel cell (FC) stack depends on the satisfactory operation of its individual cells where it is always challenging to manage the temperature gradient, water flow and distribution of reactants. In that, the design of the bipolar fuel flow path plate plays a vital role in achieving the aforementioned parameters. Further, the bipolar plates contribute 80% of the weight and 30%–40% of its total cost. Aim of this study is to enhance the efficiency of fuel to energy conversion and to minimize the overall cost of production.
Design/methodology/approach
The authors have specifically designed, simulated and fabricated a standard 2.5 × 2.5 cm2 active area proton exchange membrane (PEM) FC flow path plate to study the performance by varying the flow fields in a single ladder, double ladder and interdigitated and varying channel geometries, namely, half curve, triangle and rectangle.
Findings
Using the 3D PEMFC model and visualizing the physical and electrochemical processes occurring during the operation of the FCs resulted in a better-performing flow path plate design. It is fabricated by using additive manufacturing technology. In addition, the assembly of the full cell with the designed flow path plate shows about an 11.44% reduction in total weight, which has a significant bearing on its total cost as well as specific energy density in the stack cell.
Originality/value
Simultaneous optimization of multiple flow path parameters being carried out for better performance is the hallmark of this study which resulted in enhanced energy density and reduced cost of device production.
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K. Vellingiri, T. Ramachandran and P. Senthilkumar
Any change in physical performance of the fibre corresponds to a change in its molecular structure. Basically polyester is hydrophobic in nature due to the absence of attracting…
Abstract
Purpose
Any change in physical performance of the fibre corresponds to a change in its molecular structure. Basically polyester is hydrophobic in nature due to the absence of attracting polar groups and the dense packing in its polymeric structure. Due to the dense packing in polymeric structure and lack of hydroxyl groups of polyester it does not absorb water hence breathability is poor. The possibility of using air and oxygen plasma treatments for fibre surface activation to facilitate the improvement of hydrophilicity is attempted and has been improved. The purpose of this paper is to study the possibility of engineering the multifunctional of fabrics.
Design/methodology/approach
The treated fabric is evaluated through measuring the ultraviolet protection factor, thermal resistance, and antibacterial activity properties. Scanning electron microscopy and transmission electron microscopy graphs show deposition of nano particles (NPs) of Chitosan, TiO2 and ZnO onto the fibre after washing several times.
Findings
Air plasma-nano Chitosan treatment affects positively the antibacterial activity, thermal resistance of the fibre and air plasma-nano TiO2 and ZnO the fibre protection against ultraviolet rays. Furthermore, the plasma treatment solves an environmental problem which offers safe production process and working place and decreases the unit cost.
Originality/Value
The authors are confident that textiles will adopt this technology in the future.
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Xu Han, Xiaoyan Li and Peng Yao
This study aims to investigate the effect of ultrasound on interfacial microstructures and growth kinetics of intermetallic compounds (IMCs) at different temperatures.
Abstract
Purpose
This study aims to investigate the effect of ultrasound on interfacial microstructures and growth kinetics of intermetallic compounds (IMCs) at different temperatures.
Design/methodology/approach
To investigate the effect of ultrasound on IMCs growth quantitatively, the cross-sectional area of IMCs layers over a confirmed length was obtained for calculating the thickness of the IMCs layer.
Findings
The generation of dimensional difference in normal direction between Cu6Sn5 and its adjacent Cu6Sn5, formation of bossed Cu6Sn5 and non-interfacial Cu6Sn5 in ultrasonic solder joints made the interfacial Cu6Sn5 layer present a non-scallop-like morphology different from that of traditional solder joints. At 260°C and 290°C, the Cu3Sn layer presented a wave-like shape. In contrast, at 320°C, the Cu3Sn in ultrasonic solder joints consisted of non-interfacial Cu3Sn and interfacial Cu3Sn with a branch-like shape. The Cu6Sn5/Cu3Sn boundary and Cu3Sn/Cu interface presented a sawtooth-like shape under the effect of ultrasound. The predominant mechanism of ultrasonic-assisted growth of Cu6Sn5 growth at 260°C, 290°C and 320°C involved the grain boundary diffusion accompanied by grain coarsening. The Cu3Sn growth was controlled by volume diffusion during the ultrasonic soldering process at 260°C and 290°C. The diffusion mechanism of Cu3Sn growth transformed to grain boundary diffusion accompanied by grain coarsening when the ultrasonic soldering temperature was increased to 320°C.
Originality/value
The microstructural evolution and growth kinetics of IMCs in ultrasonically prepared ultrasonic solder joints at different temperatures have rarely been reported in previous studies. In this study, the effect of ultrasound on microstructural evolution and growth kinetics of IMCs was systematically investigated.
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Suresh V., Kathiravan Balusamy and Senthilkumar Chidambaram
An experimental investigation of hemispherical forebody interaction effects on the drag coefficient of a D-shaped model is carried out for three-dimensional flow in the…
Abstract
Purpose
An experimental investigation of hemispherical forebody interaction effects on the drag coefficient of a D-shaped model is carried out for three-dimensional flow in the subcritical range of Reynolds number 1 × 105 ≤ Re ≤ 1.8 × 105. To study the interaction effect, hemispherical shapes of various sizes are attached to the upriver of the D-shaped bluff body model. The diameter of the hemisphere (b1) varied from 0.25 to 0.75 times the diameter of the D-shaped model (b2) and its gap from the D-shaped model (g/b2) ranged from 0.25 to 1.75 b2.
Design/methodology/approach
The experiments were carried out in a low-speed open-circuit closed jet wind tunnel with test section dimensions of 1.2 × 0.9 × 1.8 m (W × H × L) capable of generating maximum velocity up to 45 m/s. The wind tunnel is equipped with a driving unit which has a 175-hp motor with three propellers controlled by a 160-kW inverter drive. Drag force is measured with an internal six-component balance with the help of the Spider 3013 E-pro data acquisition system.
Findings
The wind tunnel results show that the hemispherical forebody has a diameter ratio of 0.75 with a gap ratio of 0.25, resulting in a maximum drag reduction of 67%.
Research limitations/implications
The turbulence intensity of the wind tunnel is about 5.6% at a velocity of 18 m/s. The uncertainty in the velocity and the drag coefficient measurement are about ±1.5 and ±2.83 %, respectively. The maximum error in the geometric model is about ±1.33 %.
ractical implications
The results from the research work are helpful in choosing the optimum spacing of road vehicles, especially truck–trailer and launch vehicle applications.
Social implications
Drag reduction of road vehicle resulting less fuel consumption as well as less pollution to the environment. For instance, tractor trailer experiencing approximately 45% of aerodynamics drag is due to front part of the vehicle. The other contributors are 30% due to trailer base and 25% is due to under body flow. Nearly 65% of energy was spent to overcome the aerodynamic drag, when the vehicle is traveling at the average of 70 kmph (Seifert 2008 and Doyle 2008).
Originality/value
The benefits of placing the forebody in front of the main body will have a strong influence on reducing fuel consumption.
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Sleep quality, a crucial parameter for health and life performance, is affected by mattress components; particularly mechanical and thermal comfort management ability of the upper…
Abstract
Purpose
Sleep quality, a crucial parameter for health and life performance, is affected by mattress components; particularly mechanical and thermal comfort management ability of the upper layers. The aim of this study is to investigate effects of quilted mattress ticking fabric material (polyester, polypropylene, viscose, lyocell and their blends) on thermal comfort of the bedding system by objective and subjective measurements.
Design/methodology/approach
The permeability (air and water vapour), heat transfer, water absorption, transfer and drying behaviours of knitted quilted fabrics which influence the thermal comfort of the bedding system were investigated. Subjective coolness and dampness evaluations were gathered by forearm and hand-palm tests to provide more realistic discussion in light of fabric characteristics.
Findings
According to the results, polypropylene can be suggested for winter use with its higher air and water vapour permeabilities, lower thermal absorption and conductivities and warmer evaluation results. Lyocell can be suggested for summer use with also high permeabilities, higher thermal absorption and conductivities and cooler evaluation results. Polyester and viscose may also be considered for winter and summer in turn as a result of thermal feelings they create.
Originality/value
In addition to fabric thermal, permeability, liquid absorption and transfer properties, this study also includes subjective coolness and dampness evaluations which can provide realistic results regarding the coolness-to-touch and liquid transfer performances of mattress ticking fabrics. The relationships among objective and subjective data were investigated and the proposed subjective evaluation techniques can be used for different products.
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Rajesh Kumar S., Nishchay Sadrani and Kannan B.T.
The purpose of this study reports the effects of aspect ratio (AR) on mean flow characteristics of the cruciform orifice jet.
Abstract
Purpose
The purpose of this study reports the effects of aspect ratio (AR) on mean flow characteristics of the cruciform orifice jet.
Design/methodology/approach
The aspect ratio is the height-to-width ratio of the lobe of the cruciform shape. The aspect ratios considered are 0.25, 0.5, 0.75, 1, 2, 3 and 4. The turbulent jet flow is issued through an orifice being fitted to the jet tunnel facility. The velocity measurements are recorded with the help of pitot-static tube connected to a digital manometer setup. The Reynolds number calculated using the equivalent diameter 50.46 × 10–3 m and exit velocity 51.23 m/s was 1.75 × 105. Based on the experimental data, the streamline velocity decay plots, the potential core length (PCL), mean velocity profiles and velocity half widths were plotted, and discussions were made based on the measured data. A smoke-based flow visualization was carried out at moderate Reynolds number 5396.
Findings
The PCL remains almost constant for the aspect ratio 0.25:1 and then starts decreasing for the aspect ratio 1:4. The decrease in PCL indicates improved mixing. The off-center peaks are found along the major axis in mean velocity profiles for almost all cruciform jets. More than one axis switching occurs and can be identified by the crossover points. The location of the first crossover point shifts forward, and the second crossover point shows an oscillating trend. The flow visualization exhibits the jet evolution, and the distance up to which the jet maintains the cruciform shape is increased with the aspect ratio.
Research limitations/implications
The experiments are limited to air in air jet under isothermal conditions.
Social implications
The cruciform orifices can be used as fuel injectors and in air-conditioning systems, thereby improving efficiency and energy usage.
Originality/value
The aspect ratio effects on PCL and axis switching are used to explain the mixing characteristics. Flow visualization was also used to support the discussion.
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Sedat Özer, Yaşar Erayman Yüksel and Yasemin Korkmaz
Design of bedding textiles that contact the human body affects the sleep quality. Bedding textiles contribute to comfort sense during the sleep duration, in addition to ambient…
Abstract
Purpose
Design of bedding textiles that contact the human body affects the sleep quality. Bedding textiles contribute to comfort sense during the sleep duration, in addition to ambient and bed microclimate. The purpose of this study is to evaluate the effects of different layer properties on the compression recovery and thermal characteristics of multilayer bedding textiles.
Design/methodology/approach
In this study, woven and knitted multilayer bedding textiles were manufactured from fabric, fiber, sponge and interlining, respectively. Different sponge thickness, fiber and interlining weight were used in the layers of samples. Later, the pilling resistance, compression and recovery, air permeability and thermal conductivity of multilayer bedding textiles were investigated.
Findings
The results indicated that samples with the higher layer weight and thickness provide better compression recovery and lower air permeability properties. It was also found that knitted surfaces show the higher air permeability than the woven surfaces depending on the fabric porosity. Layer properties have insignificant effect on the thermal conductivity values.
Originality/value
While researchers mostly focus on thermal comfort properties of garments, there are limited studies about comfort properties of bedding textiles in the literature. Furthermore, compression recovery properties of bedding textiles have also a great importance in terms of comfort. Originality of this study is that these properties were analyzed together.