The present study explores the performance of novel vegetable oil-based greases containing nano-CaCO3 as an additive. A series of greases with varying nanoparticle concentrations (0 – 4 %w/w) are evaluated on a four-ball tester machine under a standard tribological test (ASTM D2266) and simultaneously in a rolling bearing at various speeds and loads against two commercial greases as the benchmark. The vibrations and shock pulse measurements (SPM) are recorded to assess the bearing performance. The tribo-dynamic investigation suggests that the eco-friendly nano-greases are at par with the commercial ones; the performance varies with the nanoparticle concentration. Under the tribological test, the third-body action of nanoparticles seems to increase friction, while the interfacial deposition (physisorption) of nano-CaCO3 and nano-CaO decreases wear. Under the bearing test, the rolling effect of nanoparticles seems to influence the vibrations, while their entrainment in the contact zone governs the carpet values. The nano-grease containing 4% nano-CaCO3 performs best under both assessments, displaying great prospects of a sustainable and potential alternative to existing environmentally unfriendly greases.
{"title":"Tribo-dynamic performance of newly developed environmentally friendly lubricating greases containing nano-CaCO3","authors":"Ankit Saxena, D. Kumar, Naresh Tandon","doi":"10.1115/1.4063138","DOIUrl":"https://doi.org/10.1115/1.4063138","url":null,"abstract":"\u0000 The present study explores the performance of novel vegetable oil-based greases containing nano-CaCO3 as an additive. A series of greases with varying nanoparticle concentrations (0 – 4 %w/w) are evaluated on a four-ball tester machine under a standard tribological test (ASTM D2266) and simultaneously in a rolling bearing at various speeds and loads against two commercial greases as the benchmark. The vibrations and shock pulse measurements (SPM) are recorded to assess the bearing performance. The tribo-dynamic investigation suggests that the eco-friendly nano-greases are at par with the commercial ones; the performance varies with the nanoparticle concentration. Under the tribological test, the third-body action of nanoparticles seems to increase friction, while the interfacial deposition (physisorption) of nano-CaCO3 and nano-CaO decreases wear. Under the bearing test, the rolling effect of nanoparticles seems to influence the vibrations, while their entrainment in the contact zone governs the carpet values. The nano-grease containing 4% nano-CaCO3 performs best under both assessments, displaying great prospects of a sustainable and potential alternative to existing environmentally unfriendly greases.","PeriodicalId":17586,"journal":{"name":"Journal of Tribology-transactions of The Asme","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2023-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41944678","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}
Lionel Simo Kamga, S. Emrich, R. Merz, M. Oehler, MichaelaGedan-smolka Gedan-Smolka, M. Kopnarski, B. Sauer, O. Koch
In this paper, solid lubricants are investigated to examine their tribological performance in a dry lubricated steel-bronze contact. The examined solid lubricants are made of polyamide (PA) and irradiated polytetrafluoroethylene (PTFE), which are chemically bonded by reactive melt extrusion. For the tribological investigations, a block-twin-disc test rig on the one hand and a three-disc test rig on the other hand were used under ambient conditions, where the solid lubricant for lubricating the steel-bronze contact was released from a block or a disc. Results from the tribological investigations are presented here, showing the friction and wear behavior in a steel-bronze contact depending on the slide-to-roll ratio in the contact between the steel disc and the compound body. Furthermore, surface analytical investigations on the steel and bronze discs were carried out. These studies showed that the chemical bonding of 20 wt-% of irradiated PTFE in PA12 improves the wear and friction behavior in steel-bronze contact significantly, due to the build-up of a transfer film of PTFE on the steel surface.
{"title":"Influence of PTFE-based dry lubricants on friction and wear behavior in dry lubricated steel-bronze contact","authors":"Lionel Simo Kamga, S. Emrich, R. Merz, M. Oehler, MichaelaGedan-smolka Gedan-Smolka, M. Kopnarski, B. Sauer, O. Koch","doi":"10.1115/1.4063116","DOIUrl":"https://doi.org/10.1115/1.4063116","url":null,"abstract":"\u0000 In this paper, solid lubricants are investigated to examine their tribological performance in a dry lubricated steel-bronze contact. The examined solid lubricants are made of polyamide (PA) and irradiated polytetrafluoroethylene (PTFE), which are chemically bonded by reactive melt extrusion. For the tribological investigations, a block-twin-disc test rig on the one hand and a three-disc test rig on the other hand were used under ambient conditions, where the solid lubricant for lubricating the steel-bronze contact was released from a block or a disc. Results from the tribological investigations are presented here, showing the friction and wear behavior in a steel-bronze contact depending on the slide-to-roll ratio in the contact between the steel disc and the compound body. Furthermore, surface analytical investigations on the steel and bronze discs were carried out. These studies showed that the chemical bonding of 20 wt-% of irradiated PTFE in PA12 improves the wear and friction behavior in steel-bronze contact significantly, due to the build-up of a transfer film of PTFE on the steel surface.","PeriodicalId":17586,"journal":{"name":"Journal of Tribology-transactions of The Asme","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2023-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48279193","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}
Wenfeng Guo, Ronghe Bai, Tianyu Guan, Yu He, Junyan Liu
Self-lubricating coating has been used in industrial applications with severe conditions, such as high temperatures, vacuum, radiation, etc. In this paper, a selective laser melting based ink-printed metal nanoparticles (SLM-IP metal NPs) rapid manufacturing method was applied to fabricate Cu-MoS2 self-lubricating coating. A tailored ink consisting metal NPs, reductant and dispersant was deposited on a stainless steel substrate, forming the laminated gradient Cu-MoS2 coating. The microstructure and mechanical properties of the composite coating were characterized. The friction and wear behavior were experimentally investigated by dry sliding wear test at room and higher temperature (>200°C). The results indicated that the upper copper sulfur molybdenum compounds layer with homogeneously distributed MoS2 provided a significant friction reduction and wear resistance. The SLM-IP Cu-MoS2 coatings showed reduced friction coefficient by 54% compare to the pure Cu coating. The transitional Cu layer mitigated the abrupt changes in physical properties and enhanced the bonding strength between the coating and substrate. Especially, under the test condition of 200°C, the Cu-40 vol% MoS2 coating also presented an excellent resistance to oxidation and had a lower friction coefficient of 0.24. This research provided a feasibility of fabricating self-lubricating coatings by the SLM-IP metal NPs method for surface engineering technologies.
{"title":"Microstructure characteristics and tribological properties of gradient Cu-MoS2 self-lubricating coating fabricated by selective laser melting of ink-printed metal nanoparticles","authors":"Wenfeng Guo, Ronghe Bai, Tianyu Guan, Yu He, Junyan Liu","doi":"10.1115/1.4063083","DOIUrl":"https://doi.org/10.1115/1.4063083","url":null,"abstract":"\u0000 Self-lubricating coating has been used in industrial applications with severe conditions, such as high temperatures, vacuum, radiation, etc. In this paper, a selective laser melting based ink-printed metal nanoparticles (SLM-IP metal NPs) rapid manufacturing method was applied to fabricate Cu-MoS2 self-lubricating coating. A tailored ink consisting metal NPs, reductant and dispersant was deposited on a stainless steel substrate, forming the laminated gradient Cu-MoS2 coating. The microstructure and mechanical properties of the composite coating were characterized. The friction and wear behavior were experimentally investigated by dry sliding wear test at room and higher temperature (>200°C). The results indicated that the upper copper sulfur molybdenum compounds layer with homogeneously distributed MoS2 provided a significant friction reduction and wear resistance. The SLM-IP Cu-MoS2 coatings showed reduced friction coefficient by 54% compare to the pure Cu coating. The transitional Cu layer mitigated the abrupt changes in physical properties and enhanced the bonding strength between the coating and substrate. Especially, under the test condition of 200°C, the Cu-40 vol% MoS2 coating also presented an excellent resistance to oxidation and had a lower friction coefficient of 0.24. This research provided a feasibility of fabricating self-lubricating coatings by the SLM-IP metal NPs method for surface engineering technologies.","PeriodicalId":17586,"journal":{"name":"Journal of Tribology-transactions of The Asme","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2023-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45296182","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}
Jamal Choudhry, A. Almqvist, B. Prakash, R. Larsson
Wear is a complex phenomenon taking place as two bodies in relative motion are brought into contact with each other. There are many different types of wear, e.g., sliding, fretting, surface fatigue, and combinations thereof. Wear occurs over a wide range of scales, and it largely depends on the mechanical properties of the material. For instance, at the micro-scale, sliding wear is the result of material detachment that occurs due to fracture. An accurate numerical simulation of sliding wear requires a robust and efficient solver, based on a realistic fracture mechanics model that can handle large deformations. In the present work, a fully coupled thermo-mechanical and meshfree approach, based on the Momentum-Consistent Smoothed Particle Galerkin method (MC-SPG), is adapted and employed to predict wear of colliding asperities. The MC-SPG based approach is used to study how the plastic deformation, thermal response, and wear are influenced by the variation of the interference between colliding spherical asperities. The results indicate a critical interference at which there is a transition of wear from plastic deformation to brittle fracture. The results also indicate that the average temperature changes linearly with increasing interference values up to the critical interference, after which it reaches a steady-state value.
{"title":"A Stress-State Dependent Sliding Wear Model for Micro-Scale Contacts","authors":"Jamal Choudhry, A. Almqvist, B. Prakash, R. Larsson","doi":"10.1115/1.4063082","DOIUrl":"https://doi.org/10.1115/1.4063082","url":null,"abstract":"\u0000 Wear is a complex phenomenon taking place as two bodies in relative motion are brought into contact with each other. There are many different types of wear, e.g., sliding, fretting, surface fatigue, and combinations thereof. Wear occurs over a wide range of scales, and it largely depends on the mechanical properties of the material. For instance, at the micro-scale, sliding wear is the result of material detachment that occurs due to fracture. An accurate numerical simulation of sliding wear requires a robust and efficient solver, based on a realistic fracture mechanics model that can handle large deformations. In the present work, a fully coupled thermo-mechanical and meshfree approach, based on the Momentum-Consistent Smoothed Particle Galerkin method (MC-SPG), is adapted and employed to predict wear of colliding asperities. The MC-SPG based approach is used to study how the plastic deformation, thermal response, and wear are influenced by the variation of the interference between colliding spherical asperities. The results indicate a critical interference at which there is a transition of wear from plastic deformation to brittle fracture. The results also indicate that the average temperature changes linearly with increasing interference values up to the critical interference, after which it reaches a steady-state value.","PeriodicalId":17586,"journal":{"name":"Journal of Tribology-transactions of The Asme","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2023-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46071503","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}
In this work, a semi-analytical model replicating 3D rolling contact problems with elastic coating layers has been proposed. The dimension reduced boundary element based model rests on the conventional half-space assumptions, with influence coefficients describing the relationship between the stress and the displacement. In this model, the influence coefficient describes the stress-strain relationship for multilayered materials, which is derived from the corresponding frequency-response functions. The governing equations for 3D rolling contact problems are solved efficiently by using the conjugate gradient method with the classical FFT-based technique to accelerate the calculation of the integral equation relating the stresses to the strains, and all the possible creepages, i.e., the longitudinal, lateral and spin creepages are considered. The results obtained with the present numerical model are compared with existing results, and good agreement is found. Some selected results are presented to show the effect of the material elasticity and the thickness of the coating, and the layering, on the traction distribution and the traction coefficient under different creepage combinations. In this way, this work provides important information related to the composition of layered coatings in rolling contact applications.
{"title":"Semi-analytical model for 3D multilayered rolling contact problems with different creepage combinations","authors":"Yinhu Xi, Bo Li, A. Almqvist","doi":"10.1115/1.4063063","DOIUrl":"https://doi.org/10.1115/1.4063063","url":null,"abstract":"\u0000 In this work, a semi-analytical model replicating 3D rolling contact problems with elastic coating layers has been proposed. The dimension reduced boundary element based model rests on the conventional half-space assumptions, with influence coefficients describing the relationship between the stress and the displacement. In this model, the influence coefficient describes the stress-strain relationship for multilayered materials, which is derived from the corresponding frequency-response functions. The governing equations for 3D rolling contact problems are solved efficiently by using the conjugate gradient method with the classical FFT-based technique to accelerate the calculation of the integral equation relating the stresses to the strains, and all the possible creepages, i.e., the longitudinal, lateral and spin creepages are considered. The results obtained with the present numerical model are compared with existing results, and good agreement is found. Some selected results are presented to show the effect of the material elasticity and the thickness of the coating, and the layering, on the traction distribution and the traction coefficient under different creepage combinations. In this way, this work provides important information related to the composition of layered coatings in rolling contact applications.","PeriodicalId":17586,"journal":{"name":"Journal of Tribology-transactions of The Asme","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2023-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46349269","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}
The water-lubricated bearings tend to be turbulent and cavitating when running at a high speed. However, the modeling of the water-lubricated bearing considering the turbulence and cavitation effects has not been studied thoroughly. For high-speed water-lubricated journal bearings, a turbulent flow model considering cavitation effect was proposed on the basis of two-phase flow theory. The simulation was conducted to show the influence of turbulence and cavitation effects on the static characteristics of the water-lubricated journal bearing. The proposed model was validated with the test by using a self-developed experimental setup. The result shows that the turbulence effect has a great impact on static characteristics of bearing, and cavitation effect significantly affects the minimum film thickness and leakage flow rate, while the friction torque is hardly affected by the cavitation effect.
{"title":"Static characteristics of high-speed water-lubricated journal bearing considering turbulence and cavitation effects","authors":"H. Zhang, Xiaohui Lin, Shuyun Jiang","doi":"10.1115/1.4063025","DOIUrl":"https://doi.org/10.1115/1.4063025","url":null,"abstract":"\u0000 The water-lubricated bearings tend to be turbulent and cavitating when running at a high speed. However, the modeling of the water-lubricated bearing considering the turbulence and cavitation effects has not been studied thoroughly. For high-speed water-lubricated journal bearings, a turbulent flow model considering cavitation effect was proposed on the basis of two-phase flow theory. The simulation was conducted to show the influence of turbulence and cavitation effects on the static characteristics of the water-lubricated journal bearing. The proposed model was validated with the test by using a self-developed experimental setup. The result shows that the turbulence effect has a great impact on static characteristics of bearing, and cavitation effect significantly affects the minimum film thickness and leakage flow rate, while the friction torque is hardly affected by the cavitation effect.","PeriodicalId":17586,"journal":{"name":"Journal of Tribology-transactions of The Asme","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2023-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41582415","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}
A model is proposed to describe and analyze hydrodynamic bearings with circumferential parallel arranged grooves along any arbitrary groove curve. The Reynolds equation is solved with finite volume method, and the additional terms of the discretized equation for any arbitrary groove curve are deducted. With the model, any groove curve could be characterized by setting an array of inclination angles, and dash-shape grooves can also be modelled by setting the matrix of flag variables reflecting whether it is in the groove. Based on the model, the transient behaviors of four groove types are analyzed by Runge-Kutta method, with the pressure distribution, rotor's center orbit and leakage flow obtained. An experiment is conducted to validate the model. Results show that the dash-shape grooves, which are asymmetrical herringboned and intermittent, have both advantages of stability and sealing. The experimental and numerical results of pressure and leakage flow show good agreement in general. The model proposed in this paper will facilitate the design of grooved hydrodynamic bearings, as different groove types can be analyzed and compared by the same model.
{"title":"A model of hydrodynamic bearings with circumferential parallel arranged grooves","authors":"Yan Li, Yanqiang Ning, Desheng Zhang, Yinhe Zhi","doi":"10.1115/1.4063026","DOIUrl":"https://doi.org/10.1115/1.4063026","url":null,"abstract":"\u0000 A model is proposed to describe and analyze hydrodynamic bearings with circumferential parallel arranged grooves along any arbitrary groove curve. The Reynolds equation is solved with finite volume method, and the additional terms of the discretized equation for any arbitrary groove curve are deducted. With the model, any groove curve could be characterized by setting an array of inclination angles, and dash-shape grooves can also be modelled by setting the matrix of flag variables reflecting whether it is in the groove. Based on the model, the transient behaviors of four groove types are analyzed by Runge-Kutta method, with the pressure distribution, rotor's center orbit and leakage flow obtained. An experiment is conducted to validate the model. Results show that the dash-shape grooves, which are asymmetrical herringboned and intermittent, have both advantages of stability and sealing. The experimental and numerical results of pressure and leakage flow show good agreement in general. The model proposed in this paper will facilitate the design of grooved hydrodynamic bearings, as different groove types can be analyzed and compared by the same model.","PeriodicalId":17586,"journal":{"name":"Journal of Tribology-transactions of The Asme","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2023-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43731752","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}
Oil-lubricated hydrodynamic bearing is a typical support for motorized spindle. However, motorized spindle supported by the oil-lubricated hydrodynamic bearing has disadvantages regarding high temperature rise and low rotational speed. To overcome this problem, this technical brief proposes novel water-lubricated hydrodynamic spiral groove bearings for the motorized spindle. A rotor-bearing static model for the motorized spindle was established considering the external loads and the tilting effect of bearings. An experimental prototype for the motorized spindle was developed, and the theoretical calculation and the experimental research on the bearing static characteristics were carried out. The result shows that the water-lubricated hydrodynamic spiral groove bearings have significant advantages in terms of low temperature rise, good high-speed performance and moderate spindle stiffness, together with the inherent low manufacture cost and high rotation accuracy of the bearings, the proposed bearings can be a potential alternative to the fluid bearing for the high-speed motorized spindle.
{"title":"Static Characteristics of Water-lubricated Hydrodynamic Spiral-groove Journal and Thrust Bearings for Motorized Spindle","authors":"Xun Huang, Ge Xu, Shuyun Jiang","doi":"10.1115/1.4063024","DOIUrl":"https://doi.org/10.1115/1.4063024","url":null,"abstract":"\u0000 Oil-lubricated hydrodynamic bearing is a typical support for motorized spindle. However, motorized spindle supported by the oil-lubricated hydrodynamic bearing has disadvantages regarding high temperature rise and low rotational speed. To overcome this problem, this technical brief proposes novel water-lubricated hydrodynamic spiral groove bearings for the motorized spindle. A rotor-bearing static model for the motorized spindle was established considering the external loads and the tilting effect of bearings. An experimental prototype for the motorized spindle was developed, and the theoretical calculation and the experimental research on the bearing static characteristics were carried out. The result shows that the water-lubricated hydrodynamic spiral groove bearings have significant advantages in terms of low temperature rise, good high-speed performance and moderate spindle stiffness, together with the inherent low manufacture cost and high rotation accuracy of the bearings, the proposed bearings can be a potential alternative to the fluid bearing for the high-speed motorized spindle.","PeriodicalId":17586,"journal":{"name":"Journal of Tribology-transactions of The Asme","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2023-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45893693","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}
This investigation demonstrates the effect of a structural hybrid of spherical silica and lamellar MoS2 combined to form a sphere used as an antifriction and antiwear additive in vegetable oil in steel-on-steel tribopair. Hybrids demonstrated improved dispersion stability due to the deposition of lightweight silica on the surface of hydrothermally prepared 2D sheets of MoS2. The concentration of nanohybrid was optimised for optimal lubricant performance, and the best region of test space is presented in this work. At the optimum concentration, the coefficient of friction (COF) was 0.03236, with an average wear volume of 2.16 x10−12 m3. The synergism of the particles significantly reduces friction and wear. The collision of the hybrid spheres with the surface has an immediate effect on it. The broken sphere of wear debris was observed under scanning electron microscopy. According to the wear debris analysis indicates that the lubrication mechanism begins with the rolling of hybrid spheres and ends with the rolling and sliding of silica and MoS2.
{"title":"The Effect of Spherical Hybrid Silica-Molybdenum Disulphide on the Lubricating Characteristics of Castor Oil","authors":"Gulshan Verma, H. A. P., O. P. Khatri","doi":"10.1115/1.4062996","DOIUrl":"https://doi.org/10.1115/1.4062996","url":null,"abstract":"\u0000 This investigation demonstrates the effect of a structural hybrid of spherical silica and lamellar MoS2 combined to form a sphere used as an antifriction and antiwear additive in vegetable oil in steel-on-steel tribopair. Hybrids demonstrated improved dispersion stability due to the deposition of lightweight silica on the surface of hydrothermally prepared 2D sheets of MoS2. The concentration of nanohybrid was optimised for optimal lubricant performance, and the best region of test space is presented in this work. At the optimum concentration, the coefficient of friction (COF) was 0.03236, with an average wear volume of 2.16 x10−12 m3. The synergism of the particles significantly reduces friction and wear. The collision of the hybrid spheres with the surface has an immediate effect on it. The broken sphere of wear debris was observed under scanning electron microscopy. According to the wear debris analysis indicates that the lubrication mechanism begins with the rolling of hybrid spheres and ends with the rolling and sliding of silica and MoS2.","PeriodicalId":17586,"journal":{"name":"Journal of Tribology-transactions of The Asme","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2023-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42937418","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}
Investigating the contact of rough spheres is constructive to wide engineering applications and scientific research. However, the coexistence of global curvature and surface roughness brings difficulty in the analysis of this problem. In this work, we present a theoretical model for the contact between a rough elastic sphere and a rigid plane. As a fundament, the whole-range contact of nominally flat Gaussian rough surfaces is dealt with by using finite element method. With the load-area relation for the contact of nominally flat rough surfaces, the local real contact area of rough spherical contact is determined, in which the local pressure is given by the Hertzian model. Then, the total real contact area of rough spherical contact is obtained by integrating over the Hertzian contact area. It is found that the load-area relation for the contact of rough spheres is linear at light loads and converges to the result of smooth spherical contact as the load increases. This rough spherical contact model is validated through direct finite element simulations.
{"title":"A theoretical contact model for rough elastic spheres","authors":"Shiwen Chen, W. Yuan, X. Liang, G. Wang","doi":"10.1115/1.4062933","DOIUrl":"https://doi.org/10.1115/1.4062933","url":null,"abstract":"\u0000 Investigating the contact of rough spheres is constructive to wide engineering applications and scientific research. However, the coexistence of global curvature and surface roughness brings difficulty in the analysis of this problem. In this work, we present a theoretical model for the contact between a rough elastic sphere and a rigid plane. As a fundament, the whole-range contact of nominally flat Gaussian rough surfaces is dealt with by using finite element method. With the load-area relation for the contact of nominally flat rough surfaces, the local real contact area of rough spherical contact is determined, in which the local pressure is given by the Hertzian model. Then, the total real contact area of rough spherical contact is obtained by integrating over the Hertzian contact area. It is found that the load-area relation for the contact of rough spheres is linear at light loads and converges to the result of smooth spherical contact as the load increases. This rough spherical contact model is validated through direct finite element simulations.","PeriodicalId":17586,"journal":{"name":"Journal of Tribology-transactions of The Asme","volume":"1 1","pages":""},"PeriodicalIF":2.5,"publicationDate":"2023-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"63503814","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}
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