Copper Fiber Research Articles

Synergic effect of metallic fillers as heat dissipaters in the tribological performance of a nonasbestos disk brake pad

Brake friction linings are made of materials with a highly complex formulation that helps in improving the braking performance. The selection of friction materials with good physical, mechanical, and thermal properties is vital, which will decide the braking performance. Apart from giving good physio-mechanical properties, metallic fillers act as heat dissipaters. The objective of this work is to study the synergetic effect of prominent heat dissipaters, namely copper fibers, brass fibers, and zinc powders. Three simplified formulations were developed with 10, 14, and 18 wt.% of these heat dissipaters and named DB1, DB2, and DB3, respectively. It was observed that the addition of heat dissipaters increased the thermal properties. Tribological properties are tested based on SAE J661 standards. It was observed that DB2 had a consistent and higher coefficient of friction of 0.503 with a higher wear rate (7.6%) while DB3 had adequate μ and lower wear rate. The same batches of brake pads were tested in an inertia brake dynamometer following JASO C406 and a wear test was carried out. It was observed that % fade and % recovery were better for DB2 in both cycles. The wear rate in terms of thickness was lesser for DB2 followed by DB1 and DB3. The wear mechanism was analyzed using a scanning electron microscope. The preference selection index method of optimization was used to evaluate the overall performance parameters of the brake friction composites. Heat dissipaters with 14 wt.% have proved to be the better performers, followed by 10 and 18 wt.%.

Каркасна теплопровідность пористих металевих матеріалів

The influence of a number of physical characteristics and parameters of metallic fiber materials on their thermal conductivity is studied in this work. Such porous materials are intended, among other things, for their effective use in two-phase heat transfer devices (heat pipes). The use of heat pipes in aircraft and space vehicles provides a number of thermophysical advantages. In particular, heat pipes significantly expand the possibilities of air cooling of heat-loaded technical devices. The thermal conductivity of capillary-porous materials-structures, which are important elements of heat pipes, significantly affects the intensity of two-phase heat transfer inside heat pipes. Frame thermal conductivity is equivalent to the thermal conductivity of materials that are conditionally continuous medium. Studies of the influence of structural characteristics of porous materials, such as porosity and parameters (dimensions) of discrete particles-fibers (fractions of the studied materials), were performed using special experimental equipment created at the I.M. Frantsevich Institute for Problems of Materials Science of the National Academy of Sciences of Ukraine (Kyiv). Porous metal structures (coatings) made of copper, nickel, and steel fibers (MPM) were investigated under conditions similar to those for space heat pipes. The porosity values ​​of the prototypes of materials were in the range of 40 to 93%. The research results showed that the following physical characteristics of capillary structures, such as values ​​of thermal conductivity of metallic materials (fiber fractions), the porosity of capillary-porous metal materials (structures), significantly affect the value of thermal conductivity of porous materials. The dimensions of discrete particles-fibers also affect in a certain way the value of the MBM thermal conductivity but to a lesser degree. The results obtained in this work are summarized in the form of empirical dependencies – formulas, providing engineering calculations of the thermal conductivity values ​​of metal fiber materials. The research results are intended for practical application in aviation and spacecraft apparatus engineering. In particular, the presented results are necessary for the development and creation of effective heat pipes with metal fiber capillary structures.

Mechanical and dynamic properties of composite rubber (RSS and SBR) with waste rubber crumb and copper fiber

Waste rubber tire is difficult to decompose by nature, but it can be reused as a part of composite rubber materials. In this research, waste rubber crumb was mixed into Ribbed Smoked Sheets (RSS) and Styrene-Butadiene Rubber (SBR) compound to form a composite rubber. The aim of this research is to investigate the mechanical and dynamic properties of RSS and SBR compounds with waste rubber crumb and copper fibber. For this purpose, another composite material in the form of copper fiber is also added which is expected to increase the damping properties of the rubber even though the mechanical properties of the rubber will decrease. RSS and SBR rubber compounds consist of 25-phr and 50-phr waste rubber crumb. Waste rubber crumb is taken from used vehicle tires with the granular size passes through the mesh sieve number # 100. 5-phr, 10-phr, 20-phr, and 30-phr of copper fibers were added into 25-phr and 50-phr respectively. The copper fiber used is 0.3 ± 0.05 mm in diameter and length to diameter ratio is 40. The results of this study indicate that the addition of waste rubber 25-phr and 50-phr decreases the tensile strength, elastic modulus, and shear modulus but increases the damping properties. The addition of copper fiber 5-phr until 30-phr decreses the tensile strength and elastic modulus but increases the shear modulus and the damping properties.

Zeolite NaY-Copper Composites Produced by Sintering Processes for Adsorption Heat Transformation—Technology, Structure and Performance

In adsorption heat pumps, the adsorbent is typically combined with heat conducting structures in order to ensure high power output. A new approach for the direct integration of zeolite granules into a copper structure made of short copper fibers is presented here. Zeolite NaY granules with two different grain sizes are coated with copper fibers and powder and sintered to larger structures. The sorption dynamics of these structures were measured and evaluated in terms of heat and mass transfer resistances and compared to the loose grain configuration of the same material. We found that the thermal conductivity of such a composite structure is approximately 10 times higher than the thermal conductivity of an adsorbent bed with NaY granules. Sorption equilibrium measurements with a volumetric method indicate that the maximum uptake is not altered by the manufacturing process. Furthermore, the impact of the adsorbent–metal structure on the total thermal mass of an adsorption heat exchanger is evaluated. The price of the superior thermal conductivity is a 40% higher thermal mass of the adsorption heat exchanger compared to the loose grain configuration.

PANCHAMAHABHUTA SIDDHANT - FIRST EVER USE OF ‘FIRST PRINCIPLES THINKING APPROACH’ IN HEALTHCARE SYSTEM

A few days ago, I just went through a thought- provoking interview of world’s richest man ‘Elon Musk’ (the Billionaire CEO of SpaceX and Tesla Company), talking about the use of ‘first principles thinking’ in his professional life. Over two thousand years ago, Aristotle defined first principles as “the first basis from which a thing is known.” In theory, first principles thinking requires you to dig deeper and deeper until you are left with only the foundational truths of a situation. In other words, ‘a first principle is a basic assumption that cannot be de- duced any further. Elon explained, to achieve the success you don't have to simplify every problem down to the atomic level to get the benefits of first principles thinking. You just need to go one or two levels deeper than most people. He further explained that first principle thinking means “boiling problems down to their most funda- mental truths” and then reasoning up from there. Through most of our life, we get through life by rea- soning by analogy, which essentially means copying what other people do with slight variations. In his own words, Elon said, let’s think about Rocket. What is a rocket made of? Aerospace-grade alumini- um alloys, plus some titanium, copper, and carbon fibre. Then he asked himself, what is the value of those materials on the commodity market? It turned out that the materials cost of a rocket was around two per cent of the typical price.”

Experiment and simulation analysis of oriented cut copper fiber heat sink for LED water cooling

In order to address the heat dissipation issue of LED light sources, an oriented cut copper fiber heat sink (Oriented-CCFHS) for LED water cooling was designed and prepared in this paper. The heat transfer performance and flow characteristics of Oriented-CCFHS, cavity heat sink, small channel heat sink, and random cut copper fiber heat sink (Random-CCFHS) were compared by experiments. Flow and heat transfer performance are obtained through Fluent simulation. Both experiment and simulation results show that the heat transfer performance of Random-CCFHS and Oriented-CCFHS were better than that of cavity heat sink and small channel heat sink. Compared with Random-CCFHS, the heat transfer performance of the Oriented-CCFHS is slightly worse, but the pressure drop is significantly smaller. The comprehensive heat transfer performance of Oriented-CCFHS is superior to that of Random-CCFHS with the same porosity. The performance of the oriented sintered heat sink under different structural parameters is predicted by numerical model. The heat transfer performance of the sintered core is optimal when the thickness of the sintered core is 2 mm. The longer sintered core with oriented copper fiber, the greater the pressure drop of heat sink and the stronger the heat transfer performance, however, the enhancement trend gradually slows down.

Relationship between the rate of a decreased oral function and the nutrient intake in community-dwelling older persons: An examination using oral function-related items in a questionnaire for latter-stage elderly people

To determine the rate of a decreased oral function using questions from the Kihon checklist corresponding to the Questionnaire for Latter-stage Elderly People and to clarify nutrient intake in older persons. This study targeted 511 older people (217 men, 294 women, average age 73.1±5.6 years old). Their oral function was evaluated using questions on the masticatory function and swallowing function from the Kihon checklist, corresponding to questions on the oral function in the Questionnaire for Latter-stage Elderly People. Participants who had at least one symptom measured were defined as the applicable group (AG). In addition, to evaluate the nutrient intake of the participants, interviews were conducted using the Food Frequency Questionnaire Based on Food Groups. The rate of inclusion in the AG was 32.9% for the total sample, 28.2% for early-stage elderly people, and 40.1% for latter-stage elderly people. The AG rates did not differ significantly between men and women. For latter-stage elderly people, the protein-energy ratio and intakes of total energy, protein, pantothenic acid, folic acid, vitamin B6, niacin, vitamin K, copper, zinc, phosphorus, magnesium, potassium, and total dietary fiber were significantly lower in the AG than in the non-AG. The evaluation of placement in the AG through questions on the oral function from the Kihon checklist corresponding to the Questionnaire for Latter-stage Elderly People demonstrated that the rate of a decreased oral function was higher in latter-stage elderly people than in early-stage elderly people. In addition, the latter-stage elderly people in the AG had a lower nutrient intake.

Improving the structural properties of composite T-joints by z-weaving of continuous metallic filaments

An experimental investigation is presented into improving the maximum load limit and other structural properties of T-shaped laminate joints by through-thickness weaving of thin metal filaments. Preforms of carbon fibre T-joints are first woven using continuous metallic or fibrous filaments made of copper, steel or carbon fibre yarns and then infused with epoxy. Stiffener pull-off tests performed on the cured T-joints show that the stainless steel z-filaments yield greater improvements to the strength and absorbed energy capacity than fibrous carbon fibre filaments by up to 80% and 30%, respectively, while copper filaments yield a smaller improvement than carbon fibre filaments. The levels of strengthening by the z-filaments depend on their volume fraction and material type, with stainless steel being more effective than copper or carbon. This study demonstrates that through-thickness weaving of continuous metallic filaments are highly effective at strengthening and toughening T-joints made of laminated composites.

Manufacturing of high strength plywood composites reinforced with copper fibers

Using wood as matrix phase layered composites are manufactured commercially, they are commonly known as plywood boards. There are many drawbacks for plywood boards like lack of strength and inefficiency to apply force in transverse direction. In this work we are trying to minimize these defects by making some changes in the manufacturing procedure. The first procedure is making holes in the matrix phase to make inter matrix bonds, which will help to improve the bond strength and apply force in lateral direction. The second procedure is introducing metallic nets to improve the load carrying capacity of the composite. The third procedure is the combination of the above two. Some design changes is required in drier to make holes in the green veneer, and there is also a change in table setting to introduce metallic net element. These procedures will help to produce high strength layered composites using wood as matrix phase with a minimum cost.

Data Siphoning Through Advanced Persistent Transmission Attacks At The Physical Layer

Data at the physical layer transmits via media such as copper cable, fiber optic, or wireless. Physical attack vectors exist that challenge data confidentiality and availability. Protocols and encryption standards help obfuscate but often cannot keep the data type and destination secure, with limited insight into confidentiality and integrity. We will investigate the feasibility of developing an awareness and integrity protocol to help mitigate physical side-channel attacks that lead to eavesdropping of data communication and denial-of-service.

Comparison of some meat and liver quality traits in Muscovy and Pekin ducks

ABSTRACT The objective of the study was to compare Muscovy and Pekin ducks for proximate analysis, colour attributes, tenderness, meat microstructure, and content of some minerals in meat and liver. The material of the study was sexed 51 Muscovy ducks and 47 Pekin ducks. At the end of the rearing period, 40 birds were selected for dissection. Duck genotype influenced the content of water, protein, fat, collagen, zinc, iron, haematin, and redness, chroma, hue angle, WB shear force, muscle fibre diameter and density of the breast muscle, and also protein, fat, magnesium, iron, haematin content, WB shear force and lightness of the leg muscle. The sex of ducks had an impact on the content of water, protein, fat, potassium, copper, on redness, chroma and muscle fibre diameter of breast muscle, and on water, protein, fat, sodium, potassium, magnesium and copper in liver content of the leg muscle. The genotype-sex interaction was significant for water, protein and sodium content, redness, chroma of breast muscles; for water, protein, sodium, magnesium and haematin content, redness and chroma of leg muscles; and for phosphorus content in the liver. Muscovy ducks had more favourable chemical composition and poorer tenderness and microstructural characteristics compared to the meat of Pekin ducks.

Критичні теплові потоки при кипінні в умовах капілярного транспорту у двофазних системах термостабілізації

The increase in heat generated by electronic components requires a need to expand the range of two-phase heat exchangers for thermal stabilization of the components. The efficiency of the two-phase systems (heat pipes, steam chambers) can be improved by using metal-fiber capillary-porous structures. Experimental studies for the conditions close to the operating conditions of heat pipes and vapor chambers described in known publications are rather incomplete. The aim of this study is to determine the boundary heat fluxes for water boiling on porous structures under capillary soaking, to investigate the influence of saturation pressure and structural parameters on the boundary heat fluxes, and to determine the optimal structural parameters of porous samples, i.e. such parameters that would allow the highest possible values of critical heat fluxes under given conditions. The authors investigate 0.3 and 0.5 mm thick capillary structure samples made of copper fibers with a diameter of 10 to 50 μm and a porosity range of 65—85%. The study has found that reducing the saturation pressure from 0.1 to 0.012 MPa leads to a decrease in the boundary heat flux values by 15—40%, depending on the effective pore diameters. The study allowed establishing that the maximum heat flux values are achieved for the samples with an effective pore diameter of 60 to 80 μm. It was also found that for the 0.5 mm thick samples, the boundary heat fluxes are 5—20% higher than for the 0.3 mm thick samples. The decrease in saturation pressure has been found to lead to a decrease in the range of two-phase heat exchange systems. For a number of samples, the authors have obtained the optimal effective pore diameters ensuring the highest critical heat flux values in the studied range.

Calculation of thermohydraulic effectiveness of the porous once-through water steam generators in laminar flow region with boundary conditions of the first kind

The paper presents results of calculations of thermohydraulic efficiency of the porous once-through steam generators with water as a model working fluid in the region of the heat-transfer agent laminar motion and with boundary conditions of the first kind. The smooth-wall cylindrical channels with different diameters were used as the reference surfaces to be compared. The following operating and design parameters were taken as a calculation base: temperature of the liquid on the saturation line at entry into the channel was: Tso = 280 °C, 300 °C, 320 °C, 340 °C, 360 °C. Temperature head, i.e. a difference between the wall temperature and temperature of the liquid at entry into the channel was: ΔT=Tw-To = 1 °C; 2 °C; 3 °C; 4 °C; 5 °C. The Reynolds number at entry into the channel was: Reo = 700; 1000; 1200; 1500; 1700; 2000; 2300. The channel porosity was: θ = 0.7; 0.75; 0.8; 0.85; 0.9. The porous material was metal felt with the copper fiber diameter of 200 microns. The channel diameter was: d =3·10-3 m; 4·10-3 m; 5·10-3 m; 6·10-3 m; 7·10-3m; 10·10-3 m. On the basis of the performed computational studies, it was concluded that for the conditions of the same mass flow rates of the coolant, with laminar mode of motion, and the same channel diameters, it is possible to achieve a significant reduction in the length of the porous once-through steam generator in comparison with the length of the smooth-wall once-through steam generator; however, under these conditions it is not possible to reduce pressure drop in the channels and, accordingly, to reduce power consumption needed for heat-transfer agent pumping. This computational study also made it possible to establish main regularities in behavior of the energy efficiency coefficients and their dependence on the model operating and design parameters. Keywords: thermo-hydraulic efficiency; porous steam-generating channels; heat-transfer agent, water; boundary conditions of the first kind; laminar flow regime.

Factorial approach for multiple optimization of mechanical properties of alternative composite material for manufacture/repair flight surfaces (WING TIP - FAIRING ASSY)/CIDFAE

Abstract Currently there is a trend in the use of alternative composite materials to be implemented in the manufacture and repair of aircraft flight surfaces of the CIDFAE (Center Research and Development of Ecuadorian Air Force); In order to obtain a material with similar or superior properties to conventional ones, studies are generated where new materials are investigated. This research proposes a method of optimization of the mechanical properties to traction, bending and impact, with a factorial approach, based on the analysis of the desirability function, this statistical methodology allows to determine the optimal combination of manufacturing parameters, in which we can measure the overall quality of the statistical model used and control the statistical significance. With the present investigation it is defined that the optimal combination that takes advantage of the mechanical properties analyzed is the one that is composed of: 6 layers of carbon fibers at 0°, 1 layer of carbon fiber at 135° and 1 layer of copper fiber at 0°. The general factorial regression model used in this research, to globally describe the analyzed properties of the alternative compound, explains the variability of the data obtained with the tests by 95.01%. This model efficiently reduces the uncontrolled variability.

Cluster front line demonstrations in summer sesamum - Impact on livelihood outcome

Sesamum is an important oilseed crop grown in Krishna district, Andhra Pradesh in summer under irrigated conditions for additional income. During 2010-11, the areaunder sesamumcultivation in the district was 699 ha with135 tonnes of production and 193 kg/ha productivity. In many parts of the district, it was observed that due to lack of knowledge on latest high yielding varieties (HYVs) and integrated crop management (ICM) practices, farmersrealized lower yields. Hence, the area under sesamum wasreplaced by short duration pulses such as blackgram and greengram. This resulted in decrease in the area under sesamum in the district. As a result, the area recorded under sesamum cultivation was nil in Krishna district during 2016-17. Pulses can be grown throughout the year, but sesamum is grown only as summer crop in the district. Sesamum is considered as a nutritional powerhouse and a great non-dairy source of calcium. It is an excellent source of calcium, copper, manganese, magnesium, iron, phosphorus, vitamin B1, zinc, molybdenum, selenium, and dietary fibre. The crop has its own importance, hence the area under this crop need to be retained.

Comparison of tribology performance, particle emissions and brake squeal noise between Cu-containing and Cu-free brake materials

The present study developed two Cu-free brake materials using carbon fiber or carbon nanotube as the replacements for copper fiber and evaluated their tribology performance, particle emissions and brake squeal noise. Results show that the coefficients of friction (COFs) of the Cu-free brake materials are lower than that of Cu-containing brake material at the braking conditions with low and medium loads. At the high load braking condition, all the braking materials exhibit comparable COFs. Cu-free brake materials present larger specific wear rates than the Cu-containing brake material. However, the application of carbon fiber can reduce the particle number emission. All brake materials exhibit comparable brake squeal noise.

On the laser scarfing of epoxy resin matrix composite with copper reinforcement

This paper explores the effects of the scanning strategy and several fundamental process parameters, like laser power, scanning speed and frequency, on the quality of a carbon-fiber reinforced polymer (CFRP) component processed by laser scarfing. Specifically, the composite consisted of an epoxy resin matrix with woven carbon fibers reinforced with copper wires. Particular attention was paid to the ablation depth and to the quality of the scarfing area. The integrity of the copper fibers is intrinsically correlated to the functionality of the material after the scarfing process, which was assessed in the paper.

Capillary performance analysis of copper powder-fiber composite wick for ultra-thin heat pipe

Excellent ultra-thin heat pipes (UTHP) require a wick with high capillary force (ΔPc) and a good permeability performance (K). In this work, a copper powder-fiber composite wick was fabricated by sintering of the copper powder and fiber mixture. Effects of the copper powder particle size, copper powder volume ratio, as well as the super-hydrophilic treatment were investigated, and the results indicate that the copper powder volume ratio is the most significant factor by orthogonal experiments. Moreover, sensitivity analysis shows that super-hydrophilic treatment contributes the lower capillary force and higher permeability, except when copper powder particle size is high to 80 mesh and powder ratio is low to 20%. Interestingly, the overall capillary performance (ΔPc·K) of the super-hydrophilic treated wicks is significantly improved. Besides, for the super-hydrophilic treated wicks, both the smaller copper powder particle size and volume ratio contribute the higher permeability and better comprehensive performance, even though a worse capillary force.

Effect of copper or carbon fiber addition to the 3D printing of polylactid samples

Abstract This paper presents the effect of additives on the quality of a product created by 3D print. The product is created by the most widely used 3D printing method - Fused Deposition Modeling (FDM). Polylactic acid (PLA) filaments are tested without and with the addition of carbon fibers or copper. The specimens are characterized by different methods, such as mechanical testing, measuring roughness by digital microscope with a large depth of field and thermal analysis. In fact, FDM is a problematic process with numerous criterions that affect printing quality. Printing parameters such as print temperature, pad temperature, print speed for 3D printing, printing orientation etc. have an important impact on the performance and quality of FDM components. Due to the correct parameters, the product of the required quality with a longer service life is obtained. The results of testing show that the quantity and choice of the right ingredient has a major impact on the mechanical properties and overall quality of the investigated product.

ASPECTS OF COMPLEXITY OF METAL-FIBROUS MICROSTRUCTURE FOR THE CONSTRUCTION OF HIGH-PERFORMANCE HEAT EXCHANGERS: ESTIMATION OF ADHESIVE STRENGTH

The paper deals with aspects of the complexity of mechanical properties of porous structures made from copper fibers and fibers reinforced with copper meshes to assess the adhesive strength of the fibrous structure and the cohesion between the components of the tested elements used for the construction of heat exchangers. All of the tested samples were characterized by macroscopic open porosity. The internal structure of the obtained connections was analyzed by metallographic techniques. Statistical relations of the connections made between the layers have been provided. The side effects of the production technology related to the “hydrogen disease” of copper have been discussed.