Lubricants最新文献

{"title":"Evaluation of Aromatic Organic Compounds as Additives on the Lubrication Properties of Castor Oil","authors":"M. T. Hernández-Sierra, José E. Báez, L. D. Aguilera-Camacho, J. García-Miranda, Karla J. Moreno","doi":"10.3390/lubricants12070244","DOIUrl":"https://doi.org/10.3390/lubricants12070244","url":null,"abstract":"In the quest for sustainable lubrication solutions, the present research explored the potential of five organic compounds as additives in castor oil (CO) to improve its lubricating properties. The compounds tested were curcumin, eugenol, 1,3-Diphenyl-2-propanone, 1,3-Diphenyl-2-propenone, and 1,3-Diphenyl-1,3-propanedione. The main results showed that each additive enhanced at least one characteristic of CO. Most of the additives lowered the density of the castor oil but increased the viscosity by up to 20%. Curcumin and eugenol were particularly effective in creating thicker lubricant films and higher film thickness ratios. Eugenol and 1,3-Diphenyl-2-propanone significantly reduced the friction coefficient by up to 25%. Wear rate and wear mechanisms were significantly reduced with all the additives, achieving a reduction in wear rate of up to 50% (CO+curcumin). All the additives, except the 1,3-Diphenyl-1,3-propanedione, enhanced the oxidation onset temperature up to 8 °C. The influence of chemical structure was also addressed. The optimal additive combination for a specific application that demands minimal friction and wear, as well as strong oxidation stability, was eugenol, followed by curcumin and 1,3-Diphenyl-2-propanone. Overall, the research contributes to the development of eco-friendly lubricants, aligning with the growing demand for green industrial applications, and highlights the significant tribological benefits of these substances as sustainable additives in biolubricant formulations.","PeriodicalId":18135,"journal":{"name":"Lubricants","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141678165","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assessing the Potential of Bio-Based Friction Modifiers for Food-Grade Lubrication","authors":"Rosa Maria Nothnagel, G. Boidi, Rainer Franz, M. Frauscher","doi":"10.3390/lubricants12070247","DOIUrl":"https://doi.org/10.3390/lubricants12070247","url":null,"abstract":"The objective of this research is to identify a bio-based friction modifier (FM) with tribological performance comparable to conventional FMs. Promising alternatives to conventional FMs, such as the FMs derived from natural sources, including rapeseed and salmon oil, were selected. Increasing concerns about crude oil prices, environmental impact, and the depletion of fossil resources have further fueled the search for renewable, biodegradable, and environmentally friendly raw materials for lubricants Tribological tests were conducted using a rheometer under non-conformal contact. The normal force, temperature, and sliding speed were varied to simulate conditions such as those found in a food extruder. To simulate cold extrusion applications, water and bio-based FM mixtures were used. The best-performing bio-based FMs were then mixed with a polyalphaolefin to simulate warm extrusion conditions. The results were compared to those obtained from mixtures of a polyalphaolefin and selected conventional FMs. The main finding of this study demonstrated that rapeseed and salmon oils, with a peak coefficient of friction (COF) of 0.16, are the best-performing bio-based FMs for reducing friction. When mixed with distilled water for cold extrusion (case 1) and with polyalphaolefin for warm extrusion (case 2), they performed similarly to the conventional FM, tallow amine, also with a maximum COF of 0.16, and significantly better than polyalphaolefin alone (maximum COF of 0.25). Consequently, rapeseed and salmon oils are suitable bio-based FM candidates to replace conventional FMs in food-grade lubrication.","PeriodicalId":18135,"journal":{"name":"Lubricants","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141678455","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Parameter Effects on the Static Characteristics of the Multi-Foil Aerodynamic Journal Bearing with Bump-Backing Foils","authors":"Yulong Jiang, Bo Xu, Qianjing Zhu, Zhongwen Huang, Dongyan Gao","doi":"10.3390/lubricants12070246","DOIUrl":"https://doi.org/10.3390/lubricants12070246","url":null,"abstract":"Due to the complexity of lubricating characteristics in the variable-sectional and multiscale clearance, the absence of an effective prediction method and theoretical basis of multi-foil aerodynamic journal bearing with bump-backing foils needs to be further developed. Hence, a modified efficient static characteristics model has been established, of which the one-dimensional curved beam theory is integrated and the elasto-hydrodynamic influence is intelligently concerned. It can be used to well predict the influential mechanisms of operational, geometric, and physical parameter effects on the static characteristics, and the important variation laws are systemically clarified. It aims to furnish a more effective and computationally efficient method and theoretical foundation for this significant type of bearing and promote its engineering design and performance optimization.","PeriodicalId":18135,"journal":{"name":"Lubricants","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141677479","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Impact of Interatomic Potentials on Atomic-Scale Wear of Graphene: A Molecular Dynamics Study","authors":"Xueqi Ye, Jie Zhang, Ping-Shun Chen","doi":"10.3390/lubricants12070245","DOIUrl":"https://doi.org/10.3390/lubricants12070245","url":null,"abstract":"Selecting an appropriate empirical interatomic potential is essential for accurately describing interatomic interactions and simulating the friction and wear of graphene. Four empirical potentials—Tersoff, REBO, AIREBO, and LCBOP—were employed in molecular dynamics simulations to study the wear process of graphene at the atomic scale. The frictional process of graphene was found to be divisible into three distinct phases: elastic deformation, plastic deformation, and wear. Using a progressively increasing load method, the critical load for each phase of graphene under four different empirical potentials was identified. Furthermore, the formation of Stone–Wales (SW) defects, bond distribution, bond breaking and healing, and wrinkle formation were analyzed in detail. Finally, a comparison was made with previous experimental results regarding friction coefficient and wear morphology.","PeriodicalId":18135,"journal":{"name":"Lubricants","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141678564","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Additives for Lubricating Oil and Grease: Mechanism, Properties and Applications","authors":"Jingbin Han","doi":"10.3390/lubricants12070243","DOIUrl":"https://doi.org/10.3390/lubricants12070243","url":null,"abstract":"Since the industrial revolution, science and technology, as well as industry of human society, have developed rapidly [...]","PeriodicalId":18135,"journal":{"name":"Lubricants","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141677722","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multi-Objective Deep Q-Network Control for Actively Lubricated Bearings","authors":"D. Shutin, Yuri Kazakov","doi":"10.3390/lubricants12070242","DOIUrl":"https://doi.org/10.3390/lubricants12070242","url":null,"abstract":"This paper aims to study and demonstrate the possibilities of using reinforcement learning for the synthesis of multi-objective controllers for radial actively lubricated hybrid fluid film bearings (ALHBs), which are considered to be complex multi-physical systems. In addition to the rotor displacement control problem being typically solved for active bearings, the proposed approach also includes power losses due to friction and lubricant pumping in ALHBs among the control objectives to be minimized by optimizing the lubrication modes. The multi-objective controller was synthesized using the deep Q-network (DQN) learning technique. An optimal control policy was determined by the DQN agent during its repetitive interaction with the simulation model of the rotor system with ALHBs. The calculations were sped up by replacing the numerical model of an ALHB with its surrogate ANN-based counterpart and by predicting the shaft displacements in response to operation of two independent control loops. The controller synthesized considering the formulated reward function for DQN agent is able to find a stable shaft position that reduces power losses by almost half compared to the losses observed when using a passive system. It also is able to prevent the established limit of the minimum fluid film thickness being exceeded to avoid possible system damage, for example, when the rotor is unbalanced during the operation. Analysis of the development process and the results obtained allowed us to draw conclusions about the main advantages and disadvantages of the considered approach, and also allowed us to identify some important directions for further research.","PeriodicalId":18135,"journal":{"name":"Lubricants","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141681382","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical Optimization Analysis of Floating Ring Seal Performance Based on Surface Texture","authors":"Zhenpeng He, Yuhang Guo, Jiaxin Si, Ning Li, Lanhao Jia, Yuchen Zou, Hongyu Wang","doi":"10.3390/lubricants12070241","DOIUrl":"https://doi.org/10.3390/lubricants12070241","url":null,"abstract":"Much research and practical experience have shown that the utilization of textures has an enhancing effect on the performance of dynamic seals and the dynamic pressure lubrication of gas bearings. In order to optimize the performance of floating ring seals, this study systematically analyzes the effects of different texture shapes and their parameters. The Reynolds equation of the gas is solved by the successive over-relaxation (SOR) iteration method. The pressure and thickness distributions of the seal gas film are solved to derive the floating force, end leakage, friction, and the ratio of buoyancy to leakage within the seal. The effects of various texture shapes, including square, 2:1 rectangle, triangle, hexagon, and circle, as well as their parameters, such as texture depth, angle, and area share, on the sealing performance are discussed. Results show that the texture can increase the air film buoyancy and reduce friction, but it also increases the leakage by a small amount. Square textures and rectangular textures are relatively effective. The deeper the depth of the texture within a certain range, the better the overall performance of the floating ring seal. As the texture area percentage increases, leakage tends to increase and friction tends to decrease. A fractal roughness model is developed, the effect of surface roughness on sealing performance is briefly discussed, and finally the effect of surface texture with roughness is analyzed. Some texture parameters that can significantly optimize the sealing performance are obtained. Rectangular textures with certain parameters enhance the buoyancy of the air film by 81.2%, which is the most significant enhancement effect. This rectangular texture reduces friction by 25.8% but increases leakage by 79.5%. The triangular textures increase buoyancy by 28.02% and leakage increases by only 10.08% when the rotation speed is 15,000 r/min. The results show that texture with appropriate roughness significantly optimizes the performance of the floating ring seal.","PeriodicalId":18135,"journal":{"name":"Lubricants","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141681445","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Impact of Mid-to-Low-Ash, Low-Viscosity Lubricants on Aftertreatment Systems after 210,000-Kilometer Real-World Road Endurance Trials","authors":"Heng Shao, Hua Hu, Yitao Luo, Lun Hua, Jinchong Pan, Gezhengting Zhu, Yan Jiao, Jingfeng Yan, Guangyuan Wei","doi":"10.3390/lubricants12070240","DOIUrl":"https://doi.org/10.3390/lubricants12070240","url":null,"abstract":"Engine lubricants globally face the challenge of meeting the demands of new engine technologies while enhancing energy efficiency and reducing emissions. Lubricants must enhance their performance and sustainability, improve reliability in complex and harsh environments, and minimize environmental impact and health risks. This study explores the influence of two different formulations of low viscosity lubricants, tested through actual road endurance trials, on a hybrid vehicle’s aftertreatment system performance and overall emission levels. The study includes 120,000 km of endurance testing in four different challenging environments in China, as well as 90,000 km of endurance testing in a typical urban and highway driving cycle in a large city. Results indicate that emissions from the test vehicles during the 120,000 km and 210,000 km durable Worldwide harmonized Light vehicle Test Cycles (WLTCs) meet China’s Stage 6 light-duty vehicle emission standards, with the 210,000 km Real Driving Emission test (RDE) results also conforming to these standards. Relative to fresh TWC, the light-off temperature increased by a mere 60 °C, and the oxygen storage capacity declined by around 19% following endurance testing. Additionally, the GPF exhibited satisfactory performance after 210,000 km of endurance testing, showing lower backpressure values compared to the fresh-coated samples, with no notable ash buildup observed in the substrate. Drawing on the outcomes of actual road endurance testing, this study illustrates that employing low-to-mid-ash-content, low-viscosity lubricants is both compatible and reliable for aftertreatment systems in present or advanced hybrid technologies. Premium lubricants facilitate vehicles in sustaining compliant and stable emission performance, even amid harsh environments and complex operating conditions. Furthermore, the tested lubricants effectively inhibit excessive aging of the aftertreatment system over prolonged mileage. Moreover, this study discusses the feasibility of rapid aging evaluation methods for aftertreatment systems based on engine test benches, juxtaposed with actual road endurance testing. These findings and conclusions offer crucial references and guidance for enhancing lubricant performance and sustainability. Subsequent studies can delve deeper into the correlation between lubricant performance and environmental impact, alongside optimization strategies for lubricants across various vehicle models and usage scenarios.","PeriodicalId":18135,"journal":{"name":"Lubricants","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141681078","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Optimization of Variational Mode Decomposition-Convolutional Neural Network-Bidirectional Long Short Term Memory Rolling Bearing Fault Diagnosis Model Based on Improved Dung Beetle Optimizer Algorithm","authors":"Weiqing Sun, Yue Wang, Xingyi You, Di Zhang, Jingyi Zhang, Xiaohu Zhao","doi":"10.3390/lubricants12070239","DOIUrl":"https://doi.org/10.3390/lubricants12070239","url":null,"abstract":"(1) Background: Rolling bearings are important components in mechanical equipment, but they are also components with a high failure rate. Once a malfunction occurs, it will cause mechanical equipment to malfunction and may even affect personnel safety. Therefore, studying the fault diagnosis methods for rolling bearings is of great significance and is also a current research hotspot and frontier. However, the vibration signals of rolling bearings usually exhibit nonlinear and non-stationary characteristics, and are easily affected by industrial environmental noise, making it difficult to accurately diagnose bearing faults. (2) Methods: Therefore, this article proposes a rolling bearing fault diagnosis model based on an improved dung beetle optimizer (DBO) algorithm-optimized variational mode decomposition-convolutional neural network-bidirectional long short-term memory (VMD-CNN-BiLSTM). Firstly, an improved DBO algorithm named CSADBO is proposed by integrating multiple strategies such as chaotic mapping and cooperative search. Secondly, the optimal parameter combination of VMD was adaptively determined through the CSADBO algorithm, and the optimized VMD algorithm was used to perform modal decomposition on the bearing vibration signal. Then, CNN-BiLSTM was used as the model for fault classification, and hyperparameters of the model were optimized using the CSADBO algorithm. (3) Results: Finally, multiple experiments were conducted on the bearing dataset of Case Western Reserve University, and the proposed method achieved an average diagnostic accuracy of 99.6%. (4) Conclusions: Experimental comparisons were made with other models to verify the effectiveness of the proposed model. The experimental results show that the proposed model based on an improved DBO algorithm optimized VMD-CNN-BiLSTM can effectively be used for rolling bearing fault diagnosis, with high diagnostic accuracy, and can provide a theoretical reference for other related fault diagnosis problems.","PeriodicalId":18135,"journal":{"name":"Lubricants","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141684837","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hydrogels for Lubrication: Synthesis, Properties, Mechanism, and Challenges","authors":"Lulin Hu, Yi Yang, Weiyan Yu, Lu Xu","doi":"10.3390/lubricants12060186","DOIUrl":"https://doi.org/10.3390/lubricants12060186","url":null,"abstract":"Hydrogels have received extensive attention as functional lubricants because of their excellent anti-friction and anti-wear properties, tunable tribological performances, and effectiveness in alleviating lubrication failures caused by the creeping or leakage of conventional liquid lubricants owing to their semi-solid nature. This review summarizes the current research advances in hydrogel lubricants fabricated with various organic and/or inorganic gelators, including organic polymeric or supramolecular hydrogels, inorganic particles-based hydrogels, and organic polymer-inorganic particle hybrid hydrogels. We illustrate not only the design strategies for constructing high-performance hydrogel lubricants but also the tribological behavior and mechanism of different types of hydrogel lubricants and their potential applications in industrial and biomimetic fields. Corresponding outlooks and suggestions for future studies have also been proposed.","PeriodicalId":18135,"journal":{"name":"Lubricants","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141102080","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}