Friction Machine Research Articles

Development of an Electrostatic Oral Cavity Generator Driven by Occlusal Force.

Mouthguard type sensors have been developed to monitor the healthcare-related information, which is expected to be used for pre-illness and preventive medicine. However, a method for supplying the power to these sensors is still an issue to be solved. In this paper, we propose an electrostatic oral cavity generator driven by occlusal force to supply the power for mouthguard type sensors. The proposed generator is a sheet form and consists of the lamination of the electret, dielectric elastomer and copper electrode. In this paper, we estimated the power generation with a piezoelectric generator and the proposed electrostatic generator. Then, the generators were designed and fabricated. The generated power of the prototype electrostatic generator was 18.0 μW. It was about 560 times larger than that of a piezoelectric generator with the area equivalent to four pairs of molars. Although the generated power was still smaller than the required power to drive the mouthguard sensor, we considered they can be comparable with each other by optimizing the design parameters of the generator.

Підвищення зносостійкості трибоспряжень зразків "сталь 45-чавун СЧ20" з геомодифікатором КГМТ-1

Increase of wear resistance of different types of tribomating which are functioning in fluid lubrication is possible due to: choosing more expensive and high quality material of samples that is not always sensible; applying some wear resistant coatings on them; selection and formation of complex composition of oil additives. Due to nanomaterials development there is a possibility of efficient use of functional additives such as geo modifiers in tribology. Due to geo modifier-based oil composites use it’s not necessary to make any structural changes of machines mated parts though their wear resistance is increased. It requires the conducting of some experimental tribological research. It was found that oil media modified by a geo modifier increase the wear resistance of working surfaces of different types of tribomating. The use of geo modifier КGМF-1 (Katerynivka friction geo modifier-1) has been suggested. Samples division into 4 types of mating according to the following characteristic features: mobility, material hardness and friction area has been suggested for more accurate picture of wear resistance changes of samples tribomating which are functioning in base and modified oil. Lower friction torque of different samples couplings in modified oil by geo modifier КGМF-1 in comparison with base oil M-10G2K was recorded while using Friction machine 2070 SMT-1 with add-on module "ring-ring". The samples wear rate in modified oil by geo modifier КGМF-1 in comparison with base oil M-10G2K was studied by method of acoustic signal amplitude measurements directly from the friction zone by a commercially produced instrument of Brüel & Kjear company. Moreover, it was recorded that the maximum wear rate of samples in their functioning in modified oil M-10G2K + КGМF-1 was 2...3 times lower, and friction torque change law is similar to the wear rate change depending on the time of testing

Ocena wpływu elektryzacji piasku na przyczepność w punkcie styku koła pociągu z szyną

The article describes a method of increasing the adhesion of the wheel to the rail based on the preliminary electrification of the abrasive-air mixture before its feed into a contact. A simulation model of the movement of sand in the system “injecting nozzle of a sandbox - a rail” is presented. The effectiveness of the proposed method to improve adhesion is confirmed experimentally. The results of experiments carried out on a friction machine, which characterize the change in friction ratio depending on the temperature with different methods of sand supply, are presented. The reduction in the consumption of sand caused by its electrification and the supply of a rational amount of abrasive substance into the contact of the wheel with the rail is estimated.

Synthesis, characterization and tribological performance of two novel borate esters containing nitrogen as a multifunctional additive in synthetic ester base oil

For the development of national industry green environmental protection, the use of zinc dialkyl dithiophosphate (ZDDP) should be reduced in the process of mechanical lubrication, two novel borate esters, SS-(5-disulfanyl-1,3,4-thiadiazol-2-yl) O-(6-stearoyl-1,3,6,2-dioxazaborocan-2-yl) carbono(dithioperoxoate) (BNSD) and 6-stearoyl-1,3,6,2-dioxazaborocan-2-yl stearate (BNCD), were synthesized and characterized by FT-IR and TGA. Tribological performance of ZDDP, BNSD and BNCD as a multifunctional additive in synthetic ester base oil were investigated under different loads using a MR-S10 four-ball and MFT-3000 friction and wear test machine. A scanning electron microscope and laser scanning confocal microscope were used to observe worn scar surface morphology of the balls. The chemical compositions of worn surface were analyzed by X-ray photoelectron spectroscopy and the tribofilm of the worn surface was observed by transmission electron microscope. The TGA curves showed that BNSD and BNCD had a better thermal stability than ZDDP. BNSD exhibits excellent anti-wear and friction-reducing properties, the P B value is increase to 784 N when the optimized concentration is 0.3% the minimum WSD of BNSD-based lubricant is approximately 0.52 mm and decreased by 35% compared with the base oil. A protective tribofilm of the ball steel was analyzed by XPS and TEM, which revealed that B2O3 and Fe2B constitute the triboilm and about 5 nm. Therefore, BNSD could be a candidate as anti-wear and friction-reducing agent in lubricants instead of ZDDP.

Accuracy characteristics of friction machines of reciprocal action

Accuracy characteristics of friction machines of reciprocal action

A new type of triboelectric nanogenerator with self-actuated series-to-parallel electrical interface based on self-synchronized mechanical switches for exponential charge accumulation in a capacitor

We present a new concept for impact-based triboelectric nanogenerators (TENG) inspired from the electrostatic machines of the 18th century. With this system, the electrical energy converted from the mechanical domain is automatically accumulated in a large capacitance without the need of diodes. Our TENG has three electrodes and self-synchronized/self-actuated mechanical switches, which automatically and repeatedly connect the capacitances of the system according to their series and parallel configurations in order to reproduce a behaviour similar to the Bennet's charge doubler. The movable and freestanding electrode is covered with triboelectric patches that drastically decreases the start-up time. The output voltage, and so the harvested energy, increases exponentially until either the output voltage reaches the air dielectric breakdown or a saturation occurs because the electrostatic forces become comparable to the mechanical ones. We have developed a complete numerical model that takes into account both electrical and mechanical forces and is able to show the saturation phenomena due to the high electromechanical coupling occurring at high voltage. This model has been validated with practical experiments where the prototype were excited with a sinusoidal acceleration of 0.2 grms at 5 Hz. This new and diode-free concept can be applied to any TENG having at least one variable capacitor to boost the mechanical-to-electrical energy conversion.

Закономірності динаміки зміни триботехнічних характеристик покриттів, сформованих триботехнологіями відновлення

In this paper, the laws of the dynamics of the changes of such tribotechnical characteristics as the moment of friction and the intensity of wear of the formed coatings by tribotechnology of restoration with the use of mixtures of geomodifiers KGMF-1 from natural substances based on the clay of the Katerinovsky deposit in the Kirovograd region of Ukraine are considered. The geomodifier KGMF-1 was added to the engine oil M10G2k. The study of the friction moment was carried out on a friction machine 2070 SMT-1 on various types of tripartite specimens and parts differing in area of the friction zone and the magnitude of its hardness. The processes of friction and wear were investigated by the method of acoustic emission on the Bruel & Kjear instrument with the determination of the intensity of wear. The results of experimental studies have shown that the dependence of the moment of friction and the intensity of wear on the duration of the test for the strains I and III types are identical. Investigation of the patterns of these characteristics on samples without endurance and endurance of 100 and 300 days revealed the difference: when maintaining the coatings for 100 days tribotechnical characteristics are the best, with the friction moment practically does not change, however, the duration of the time of spin and the intensity of wear decreases.

Development of a Dielectric-Gas-Based Single-Phase Electrostatic Motor

Electrostatic motor can work as a supplement to the electromagnetic motor due to its simple structure, low cost, light weight, and high efficiency. This paper presents a dielectric-gas-based single-phase electrostatic motor with simplified construction. The motor design is focused on increasing the capacitance, subsequently the torque, to make the electrostatic motors competitive with the electromagnetic ones. Three-dimensional (3-D) finite element analysis (FEA) simulation and optimization process of the electrostatic motor is performed. A 50 W electrostatic motor with the torque of 0.25 N·m, which is the same order in magnitude with the fluid-filled electrostatic machine and induction machine at the similar power level, is designed. Losses including the friction loss, windage loss, and dielectric loss are predicted. Thermal fields are analyzed using FEA and the electrostatic motor presented can work stably at high ambient temperature. 3-D printing is used to build a prototype machine to eliminate the process of mould manufacture and achieve a weight reduction. Predicted capacitance of machine is compared with measured result and good agreement is achieved.

Evaluation of the extent of damage to the esophageal wall caused by press-through package ingestion

Press-through package (PTP) is the most common accidentally ingested foreign body in Japan. Accidental ingestion of PTP can result in esophageal damage. An approach for evaluating the risk of esophageal injury has not been established. Therefore, we used porcine esophageal tissue and silicone sheets to establish a method for assessing the risk of esophageal damage on accidental PTP ingestion. We pathologically evaluated porcine lower esophageal tissue using a scratch tester. Using porcine esophageal tissue, scratch tests were performed with 4 test objects and pathological damage was compared. It was assumed that each object was accidentally ingested. The objects were polyvinylidene chloride (PVDC)-coated polyvinyl chloride (PVC) PTP, soft PThPa, round PTP, and a disposable scalpel. The porcine esophagus was replaced with a silicon sheet, and an automatic friction machine was used for quantitative evaluation. The silicon sheet was scratched using HHS 2000 with 750-g load at 50 mm/min. We investigated the frictional force exerted on the surface for each of the objects. The degree of damage (depth) was the highest for the disposable scalpel, followed by PVDC-coated PVC PTP, while the degree of damage (depth) was the lowest for soft PThPa and round PTP. The mean frictional forces on the silicon sheet were 524.0 gf with PVDC-coated PTP, 323.5 gf with soft PThPa, 288.7 gf with round PTP, and 922.7 gf with the disposable scalpel. We developed approaches to qualitatively and quantitatively evaluate the risk of esophageal damage after accidental PTP ingestion. Our findings indicate that the risk of gastrointestinal damage after accidental PTP ingestion is low with soft PTP and round PTP.

Determining the influence of carbon black in oil on the wear resistance of elements in the tribological system "steel – oil – bronze"

The results of experimental research into the influence of the concentration of carbon black in industrial oil I-30А and on wear resistance of the tribological system steel-oil-bronze are presented. It is assumed that carbon black, obtained by the electric arc method under laboratory conditions, consists of conglomerates and micro-and nanoparticles of carbon, which are found in a wide range from nanometers to tenths of millimeters.The procedure, materials, and equipment for experimental studies of wear resistance of the parts of the tribosystem steel-bronze on the friction machine SMC-2 was shown. The research procedure methodology involved the variation by two independent factors: concentration of carbon black in industrial oil I-30А and external loading. Sliding velocity, contour area of the contact and initial temperature of the tribosystem remained constant factors.The obtained experimental data made it possible to establish two main patterns that characterize the process of friction and wear in the studied tribological system. The first pattern reveals the influence of the concentration of carbon black in industrial oil I-30А and external load on friction torque in the couple steel‒bronze. The second pattern reveals the influence of the same factors on wear resistance of the parts that were tested on the friction machine. The obtained patterns correlate among themselves and determine the scope of rational concentration of conglomerates of micro- and nanoparticles of carbon in industrial oil I-30A, which was applied as a lubricant in the tested tribological system.At the final stage of the research, the surfaces of the parts of friction were studied at the atomic-force microscope Solver P47-Pro made by manufacturing company NT-MDT. These studies made it possible to reveal the mechanism of modification of the surface layer of steel and bronze by carbon nanoparticles in their interaction in the tribological system at friction.

Analysis of Electronic Electrostatic Generators

This brief presents a systematic procedure for the formulation of the equations required for the algebraic analysis of electrostatic generators used for energy-harvesting purposes. The considered circuits are assumed to be composed of variable and fixed capacitors, diodes, and switches. Guidelines are presented for the systematic matrix formulation of the required equations and for the calculation of the voltage multiplication factor in the charging transient, applicable also for the analysis of the operation at steady state generating energy. Examples are then presented, with the application of the procedure in the analysis of two structures. The first was already analyzed by an approximated method and the last was not previously studied in detail.

Mechanical‐to‐Electrical Energy Conversion with Variable Electric Double Layers

The electromagnetic generator requires sophisticated power take‐off systems to effectively capture low‐frequency mechanical motion such as ocean waves and human gait. Conversely, electrostatic generators are variable capacitors, which harness charge separation processes that can directly capture low‐frequency mechanical energy. The fundamentals of mechanical‐to‐electrical energy conversion with an electrostatic generator that exploits the high energy density of electric double layer (EDL) capacitors and varies capacitance by physical manipulation of the electrode–electrolyte interfacial area are elucidated. A model system is designed where all experimental parameters are easy to access in order to gain a detailed understanding of the energy flow in this conversion process. The system, termed a variable EDL generator, is based on titanium electrodes in NaCl aqueous electrolyte and operated as a charge pump. The net positive electrical energy generation of the system in the voltage–charge work‐conjugate plane is analyzed, and it shows that the variable EDL generator can be scaled‐up to spin an electric motor and increase the output power of the generator through the use of waste heat. The detailed analysis of this energy conversion principle suggests multiple avenues to enhance the performance of the variable EDL generator.

Preparation and Tribological Properties of Modified Field’s Alloy Nanoparticles as Additives in Liquid Poly-alfa-olefin Solution

This study described the synthesis and the tribological properties of surface-modified Field’s alloy nanoparticles, which were prepared by a facile one-step nanoemulsion method and using ethyl carbamate as a surfactant, as additives in liquid poly-alfa-olefin (PAO) oil. The size and morphology of nanoparticles were investigated by transmission electron microscopy (TEM). The zeta potential, viscosity, and stability properties of the surface-modified nanoparticles suspended in PAO oil (called nanofluid) with different mass concentrations were measured by a viscometer and Zeta potential analyzer, respectively. The tribological properties of the nanofluid were tested by a ball to disk wear and friction machine. Compared with pure PAO oil, the results showed that the nanofluids had better lubricating behaviors. When the mass concentration of modified nanoparticles was 0.08 wt. %, both the friction coefficient and the wear scar diameter were the lowest.

Quantitative analysis of the lifelong production of conidia released from single colonies of Podosphaera xanthii on melon leaves using electrostatic techniques

Using an electrostatic rotational spore collector, we consecutively collected all of the conidia produced from single colonies of melon powdery mildew (Podosphaera xanthii Pollacci KMP-6 N) on leaves of living melon plants throughout the lifetime of the colony in a natural environment, and counted all conidia that were attracted to insulators. The collector consisted of an insulated round plastic container, a conductor (copper) film, an insulator (collector) film, an electrostatic voltage generator and a timer mechanism. Negative charge was supplied from the voltage generator to the conductor film, and the negatively charged conductor film caused dielectric polarization of the insulator film. The insulator film, which creates an attractive force for trapping conidia that enter the field, was placed ca. 2 cm from the apex of the single colony. Released conidia were successfully attracted to the electrostatically activated insulator films. Each collector film was exchanged for a new insulator film at 24 h intervals until KMP-6 N ceased to release conidia from single colonies. During a colony’s lifespan, KMP-6 N released an average of 12.6 × 104 conidia from each of the single colonies at ca. 744 h. Additionally, we found that 1) the number of conidia released from single colonies in daytime was larger than that in night-time, 2) conidia were released from single colonies for ca. 2–4 h longer in spring or summer than in autumn or winter, and 3) release of conidia from KMP-6 N decreased as light intensity declined. Thus, conidial release from conidiophores is affected by day-length and light intensity.

High Torque Density Macro-scale Electrostatic Rotating Machines: Electrical Design, Generalized <inline-formula> <tex-math notation="LaTeX">$d-q$</tex-math> </inline-formula> Framework, and Demonstration

The use of advanced dielectric liquids and manufacturing techniques for enhanced surface area per unit volume, along with other multiplicative gains, is enabling macro-scale electrostatic machines with competitive torque densities. This emergence prompts the need for circuit modeling—that guides machine design and drive controls—rooted in the canon of well-established electromagnetic machinery practices. In this study, prior dielectric and manufacturing innovations are combined with a newly developed unified electrostatic machine $d-q$ -axis framework to form a machine that demonstrates industrial utility. Design, equivalent circuits, and performance are validated by an experimental prototype intended for low-speed direct-drive servo actuators. A prototype electrostatic machine was constructed entirely of aluminum and printed circuit boards, and possesses active material torque densities ≥1.4 N⋅m/kg and ≥2.65 N⋅m/L without the need for forced air or liquid cooling. Additional features include near zero loss at stall and low torque ripple.

Modeling of the Wear Resistance of Epoxy Composites According to Changes in Their Mechanical Characteristics

Due to the complex of their physicomechanical and operating characteristics, the composite materials based on thermosetting polymers are extensively used in all branches of Ukrainian industry for the corrosion and wear protection of the equipment and, in particular, as antifriction materials. We propose a model of these composites based on epoxy oligomers and aluminum oxides capable of the evaluation the wear rate of the material without using a friction machine. For this purpose, we apply the similarity theory. According to this theory, in the case where all corresponding dimensionless characteristics of two different processes are identical, these processes are similar. On the basis of the experimental data obtained in analyzing the friction coefficient, the elasticity modulus, and the hardness of epoxy composites, we propose a model for the prediction of the wear characteristics of materials depending on the content of aluminum oxide. The application of this model guarantees the agreement between the results of modeling and the experimental data.

Electrode Structure Effects on Electrostatic Spray System Efficiency for Bladeless Wind Power Generation

The liquid medium can be atomized into small droplets and then it moves towards the reverse direction of the electric field force under the wind action, which can increase overall electrical potential energy of the system and realize the conversion of wind energy to the electric energy. In this paper, multi injection needle mesh electrode is taken in the electrostatic wind power generation system as the research object. Based on the ANSYS simulation platform, electric field distribution and the influence of electric field intensity on spray effect at injection needle in different structure like quadrangular, rhombic, circular and hexagonal high pressure electrodes are studied. The results show that the voltage level of discharge terminal in circular electrode structure is significantly higher than that of the other electrode structures and voltage level is needed for multiple jets significantly lower than the other electrode structures.

Epoxy antifriction wollastonite-filled materials

Introduction. Domestic mineral natural-origin filler ‘wollastonite’, also known as calcium methyl silicate, is widely used as a base for wear-resisting epoxy antifriction materials. Due to anisodiametric shape of its particles, wollastonite functions as a micro reinforcement fibre enhancing adhesion strength and wear resistance of epoxy compositions, improving their antifriction properties, especially when organomodifying by quaternary ammonium salts. In this regard, the investigation of the impact of chemical composition of such surfactants as quaternary ammonium salts on the properties of epoxy compound materials presents utmost interest for researchers developing low-friction materials. Materials and methods. Epoxy diane resin ED-20 was hardened with aminoalkylphenol AF-2. Content of epoxy hardener was determined by equimolar ratio of epoxy groups to amine groups. Domestic wollastonite of the grade Miwoll 10-97 was used as filler, particle length to the diameter correlated as 15:1. The wollastonite surface was activated with surfactants belonging to domestically produced quaternary ammonium salts. Wear resistance of specimens was tested by means of the vertical optical caliper IZV-1. Friction coefficient was estimated with the assistance of the computer-automated frictional machine CSM Instruments Tribometer. Adhesion strength of glue joint was determined as per GOST 28840-90 standard. Two bars of sheet aluminium were used as glued surfaces as per GOST 14759-69 standard. Results. Reduction of wear of epoxy coatings when modified with micro reinforcing wollastonite can be explained by the increase of cross-linking degree of the polymer. The length of alkyl radical of quaternary ammonium salts used for wollastonite surface activation affects the intervals between the epoxy links. As the quaternary ammonium salt chain length is growing, wear of epoxy materials is reducing. Introduction of the wollastonite containing metallic oxides in the epoxy composites increases wear resistance and adhesion strength and reduces coating friction coefficients. Conclusions. Hardened with the AF-2 and filled with the wollastonite of the Miwoll 10-97 grade, the epoxy compound materials have enhanced wear resistance and adhesion strength and lower friction coefficient. The best result is observed when applying wollastonite modified with a surfactant belonging to the class of quaternary ammonium salts. The wollastonite can be used for practical purposes as a perspective reinforcing agent for epoxy materials with improved wear resistance, enhanced adhesion to metals and reduced friction coefficient.

Phase Composition and Wear Resistance of Coatings Formed on the VT6 Titanium Alloy by Plasma Electrolytic Oxidation

The growth kinetics of the coating during the plasma electrolytic oxidation (PEO) of the VT6 (Ti–6Al–4V) alloy with a specified density of 10 A/dm2 in an alkaline aqueous solution containing sodium aluminate (NaAlO2) in an amount of 40 g/L is investigated. The wear resistance of coatings of different thicknesses (30 and 80 μm) formed on the VT6 alloy is studied by the “pin-on-disc” test using a “High-temperature tribometer” automated friction machine and WYKO NT1100B optical profilometer. The dependences of the phase composition of coatings on the PEO duration and wear resistance of coatings on this composition are established. The following growth mechanisms of the coating thickness, which explain the growth kinetic features, are proposed: (i) the migration and diffusion of metal cations to the external phase interface in segments adjoining the microdischarges; (ii) the thermochemical transformation of deposited ions or polyanions, in particular, sodium tetrahydroxoaluminate; and (iii) high-temperature oxidation of the metallic base of the bottom of through coating pores, in which the plasma anodic microdischarges were implemented. The considered equivalent circuit of proceeding the anodic component of the alternate current during the PEO of the titanium alloy allows one to understand the causes of a substantial initial decrease in the coating growth rate during the PEO of the VT6 alloy without lowering the anodic voltage. The feature of this circuit is the presence of rheostats, because the flowing resistance of alternate current components depends largely on the PEO duration. It is shown that the presence of the high-temperature modification (α‑Al2O3) in the coating based on spinel TiAl2O5 makes it possible to increase the wear resistance of the VT6 alloy almost sixfold if the coating thickness is ~80 μm.

A Novel Design of Static Electrostatic Generator for High Voltage Low Power Applications Based on Electric Field Manipulation by Area Geometric Difference

An electrostatic generator is an electromechanical device that produces static charges at high voltage and low current. This technology is mature enough, as it has existed for many centuries. Nevertheless, the working principle of most of the commonly used electrostatic generators is still based on typical mechanical methods, which consequently makes them bulky and limits their controllability on the generated charges, e.g., Van de Graaff generator that uses the friction between two different materials to generate electrostatic charges. In this paper, a novel design of a static electrostatic generator (SEG) is presented based on a completely different idea compared to existing electrostatic generators, which offers several potential benefits. The idea originates from the study of a parallel plates capacitor—for instance, if a voltage is applied to two plates of a capacitor, then according to Gauss’s law, both of the plates must have an equal and opposite charge. Suppose one of the plates has a different geometry, with a shorter length than the other, then the number of the charges on both plates will not be equal. Thus, by manipulating the geometrical area of the device, a different number of charges will be generated on both metal conductors. Therefore, a different number of charges are generated on both conductors; hence, by connecting both conductor plates of the capacitance, excess charges will remain on the device. The proposed idea was assessed with computer simulations using finite element and finite difference methods for a variety of different scenarios to determine the optimal design of the proposed device. The device offers several advantages over traditional electrostatic generators, such as that it can generate either positive or negative charges by merely reversing the polarity of the DC source; additionally, it is very simple, lightweight, and easy to manufacture. In particular, the principal advantage of the proposed device is that it is a static one, and no mechanical movement is required to produce charges. Further, the design is general enough and scalable. The simulation results demonstrate the performance of the proposed device.