Lubrication Science最新文献

Considering the rapid liquid transport characteristics of bionic dragonfly wings, an experimental investigation into the stability and drag reduction properties of an air film on various textured surfaces is being conducted. The study examines the impact of different wetting gradient textures on the stability and drag reduction properties of air film. Experimental results demonstrate an enhanced fluid transport efficiency, resulting in a maximum drag reduction of 9.1%, attributed to the size effect of the multi-scale structure of bionic dragonfly wings. Surfaces featuring wetting gradients exhibit increased stability of the air film within the texture and the ability to trap air bubbles. Based on a near-wall flow two-phase flow theory model, the simulation considers the morphological changes of the air film at structured interfaces and their influence on near-wall flow characteristics. The results indicate that the drag reduction effect arise from the slippage effect between the internal vortex in the air film inside the texture and the flow field near the wall surface. The synergistic effect of near-wall flow fields among multiple texture layers is evident. This interplay across different regions contributes to the sustained drag reduction within the near wall area.

Regarding its wide range of applications in different industries, such as oil and gas, and for manufacturing equipment used to control pollution and recycle industrial wastes, Inconel 686 turning process is highly important. The alloy is highly resistant to high temperatures and corrosion, and thus it can preserve its properties at high temperatures. Due to its low heat transfer coefficient and work hardening during operation, Inconel 686 is considered a difficult-to-cut material, and hence, turning Inconel 686 is challenged with major limitations regarding input parameter level and cutting fluid and issues such as reduced surface quality. The input parameter level and cutting fluid limitations might severely harm the environment and humans, decrease the machining efficiency and keep cleaner production goals out of reach. Novel cooling methods such as cryo-MQL can contribute to achieving cleaner production goals. Cooling methods improve the machining performance and prohibit any damage to the surface integrity. In this study, cryo-MQL, along with carbide-coated tools and biodegradable vegetable oil, was adopted. The efficiency and success rate of cryo-MQL were evaluated by comparing the results with those of MQL and wet methods. A wide range of output parameters, such as residual stresses, cutting zone temperature, cutting forces, tool wear, surface smoothness, surface defects and micro-hardness, were assessed by changing the cutting speed and feed rate. The results indicated that cryo-MQL could reduce the cutting forces, tool wear rate, cutting zone temperature and residual stresses while improving the surface quality. Moreover, environmental concerns were completely dealt with. Due to the increased possibility of higher input parameter levels, the time and cost of the cutting process were significantly reduced.

The high tensile strength and high resistance of nickel-based superalloy 686 against high temperatures and corrosion rates have made it a widely used in important applications such as the aerospace industry, high pollution- and corrosion-resistance equipment manufacturing and petrochemical industry. Therefore, the machining of this advanced alloy with its unique properties is extremely important and can be challenging. Significant increase in input parameters levels, reduction of machining costs, improvement of surface and subsurface properties and clean production are among the issues that should be considered in dealing with Inconel 686 turning operations. Simultaneous application of advanced tools such as polycrystalline diamond (PCD) and polycrystalline cubic boron nitride (PCBN) and optimised minimum quantity lubrication (MQL) method and evaluating the results obtained with a wide range of output parameters related to machining process performance and tribological properties can be proposed as an innovation and a solution to this problem in this article. This study analyses several output parameters with different speeds and feeds to evaluate the effect of cutting insert type on machining process performance and tribological properties. The output parameters include tool wear, residual stress, cutting zone temperature, surface smoothness, machining forces and workpiece surface defects. The results indicated that using the optimised MQL method reduces the size of lubricant droplets and increases the surface covered by cooling. With these changes, the performance of the machining process and the parameters related to the surface integrity increase significantly. Among the parameters associated with the performance of the machining process, the PCD tool reduces the cutting zone temperature by 23%, the tool wear by 19% and the machining forces by 18% compared to the PCBN tool. In the parameters related to surface integrity, this method reduces the residual stress by 19% and the surface roughness by 9% compared to the PCBN tool. From the production index perspective, the PCD tool can significantly increase the cutting speed and feed rate, reducing production time and costs.

The prediction of churning power loss has been a difficult problem in the analysis of spur gears. Thus, an analytical prediction model based on the redefinition of churning power loss and energy transformation is proposed to estimate the churning power of spur gears. Churning power loss is defined as the combination of the power loss due to the drag on the end face, the power loss due to the tangential flow, the power loss due to the acceleration of lubricants in the tooth space, and the power loss due to the centrifugal force. Several comparisons of prediction and experimental results are made and good agreement of those is obtained. Finally, the components of churning power loss under different gears and work conditions are analyzed, and the influences of each part on churning power loss are obtained.

In this study, it is aimed to increase the wear and fatigue performance of aluminium-based sliding bearing material by using silver nanoparticles (AgNPs) added lubricant and shot-peening process. The main purpose is to minimise the wear of the bearing material by penetrating AgNPs added lubricants into the rough surfaces formed by shot peening. Almen intensity, coverage and shot size parameters in the shot-peening process were analysed in terms of hardness, surface roughness and fatigue strength. The shot-peened aluminium bronze was subjected to wear experiments under dry, pure water and AgNPs added lubricant conditions. The wear test results were analysed in terms of friction coefficient, wear volume and surface roughness parameters, and the interaction of lubricant and shot-peening parameters was evaluated. According to the results of the shot-peening experiments, the Almen intensity was the most effective parameter in terms of hardness and surface roughness (91.62%). It was concluded that the hardness value was 8% higher at high Almen (12–14A) intensity compared with low Almen intensities, and the shot-peening process could increase the fatigue strength by ~21 times. According to the wear tests, the most effective parameters were 4–6 Almen intensity and AgNP-added lubricant.

The anti-emulsification property of lubricating oil is an important index to measure the quality of oil. In this paper, the behaviour of surfactants such as lubricating oil additives at the oil–water interface and the influence of the position of ethylene oxide (EO) and propylene oxide (PO) in the block polyether demulsifier on the demulsification effect were investigated by molecular simulation and experimental verification. The properties of seven lubricating oil additives with different functions and two pairs of isomers were investigated by molecular simulation, and their demulsification effects were verified by experiments. Some simulation results such as interface thickness and density distribution can accurately predict the experimental demulsification effect. Moreover, it was found that the position isomerism of surfactants affected the demulsification performance by changing the lipophilic balance and interface properties. The demulsification performance of sequenced copolymers is generally better than that of anti-sequenced copolymers. The accurate prediction of molecular dynamics simulation makes the selection of lubricating oil demulsifier more extensive and has practical application value.

This paper proposes an optimisation method for fabricating composite materials and functionally graded structures. Using the proposed method, 3D printing of copper (Cu)–polyethylene (PE) composite, Al₂O₃–ZrO₂ ceramic composite and functionally graded CuO foams are utilised. This work aims to advance the capabilities of additive manufacturing by leveraging nature-inspired approaches to create complex, tailored structures with enhanced performance across various industries. The major objective of the proposed method is to reduce the feed rate and increase the airflow rate and airflow temperature for the heat transfer process. Using the proposed technique in the advanced preparation conditions, Cu–PE composites with unreliable Cu substances are fabricated. The PE binder particle is melting as well as forming thick composites by means of soft surfaces. Using the proposed AHO approach, functionally graded materials with common distributions can be efficiently optimised. By then, the proposed model is implemented on the MATLAB platform, and its execution is calculated using the current procedures. The proposed technique displays superior outcomes in all existing methods like wild horse optimiser, particle swarm optimisation and heap-based optimiser. The proposed method shows a throughput of 57 mm³. The existing method shows the throughput of 32, 27 and 45 mm³. The results show that the proposed method has higher throughput compared with existing methods.

The present research analyses the power consumption (P _c) and surface roughness (R _a) in hard turning of high-strength low-alloy (HSLA) grade AISI 4140 steel using a recently developed AlTiSiN-coated carbide tool under different cooling-lubrication conditions (dry, flooded, nanofluid-MQL). The nanofluid was prepared by mixing the MWCNT nanoparticles with an eco-friendly automotive radiator coolant (base fluid). The cooling-lubrication performance is investigated briefly by comparing the machining responses like machined surface morphology, tool wear, cutting force and temperature. The experiments associated with 46 trials were performed by considering various machining variables, namely cutting speed, nose radius, depth of cut, feed and cooling-lubrication methods. From the perspective of predictive modelling and multi-response optimisation, response surface methodology has been employed to minimise power consumption and surface roughness. Thereafter, the predictive modelling and optimisation results are implemented for economic analysis and energy-saving carbon footprint evaluation. This innovative research also addresses comparative environmental sustainability evaluation in hard turning under different cooling-lubrication conditions using a life cycle assessment methodology for cleaner and safer production. Results indicate that cutting speed was the most influential item in power consumption enhancement. Furthermore, compared with dry and flooded turning, lower cutting force, reduced cutting temperature, shorter width of flank wear and better surface morphology were obtained under nanofluid-MQL machining. It has been observed that nanofluid-MQL machining outperformed sustainability improvement concerning techno-economically viable societal acceptable and environmental friendliness.

The tribological properties of lubricants containing the same additives often vary with varying hardness and composition of the frictional parts. This means that, in terms of the effectiveness of lubricant additives, most of current researches using GCr15 steel to assemble the frictional pair could not be directly cited by the moving parts made of other materials. Aiming at verifying if RNS-1A-PIBSA (referring to amino-functionalized silica nanoparticle [RNS-1A] after secondary surface-capping by polyisobutylene succinic anhydride [PIBSA]) is suitable for multiple frictional parts made of different materials with varying hardness and composition, herein we investigate its applicability an additive in poly-alpha-olefin 6 (PAO6) base oil to three types of sliding pairs constructed from GCr15 steel, #45 steel, and ductile iron with much different hardness and composition by SRV-5. A series of analyses of worn surface morphology and composition demonstrate that, independent of the composition and hardness of the frictional pairs, RNS-1A-PIBSA added in PAO6 base oil can form silica deposition film on the rubbed surfaces of the three kinds of sliding pairs, thereby effectively reducing friction and wear. Besides, we also examine the effect of RNS-1A-PIBSA on the thermal stability of the PAO6 base oil, and found the nano-additive RNS-1A-PIBSA can delay the thermal decomposition of PAO6 base oil to some extent, which is favourable for its application in lubrication engineering.

In this paper, the friction properties of the port pair with non-smooth surface in the pump were studied. The lubrication film was modelled and simulated to analyse dynamic pressure, velocity vector and friction coefficient. Tests were made for studying the effects of pit shape and revolution speed on friction properties of glass fibre epoxy resin (GFER) samples under seawater lubrication, with the wear of the surface and friction coefficient discussed. The results show that GFER is mainly manifested as adhesive and abrasive wear during the tests. The simulations and tests suggest that the hydrodynamic lubrication effect is improved by increasing revolution speed and using non-smooth surfaces, with the friction coefficient being decreased. Moreover, a roughness test was conducted, and it was found that the Ra value of the 316L sample decreased, whereas the Ra value of the GFER sample increased.