Running-in quality can be improved by optimizing the running-in parameters (load, speed and running-in time). The relationship between running-in quality and the fractal dimensions of friction signal and wear surface is analyzed. It shows that the larger the fractal dimension, the better the running-in quality. A multi-objective optimization design of the running-in parameters of the main bearing is carried out, using a non-dominated sorting genetic algorithm with elite strategy. The optimization targets are the large fractal dimension of friction coefficient, the large fractal dimension of wear surface, and small running-in time. It shows that the selection principles of running-in parameters are different for different stages and priorities. The optimal running-in parameters listed in this paper provides a specific reference to the optimal design of the three-stage running in of main bearing.
{"title":"Multi-objective optimization of three-stage running-in process for main bearing of marine diesel engine","authors":"","doi":"10.1115/1.4062298","DOIUrl":"https://doi.org/10.1115/1.4062298","url":null,"abstract":"\u0000 Running-in quality can be improved by optimizing the running-in parameters (load, speed and running-in time). The relationship between running-in quality and the fractal dimensions of friction signal and wear surface is analyzed. It shows that the larger the fractal dimension, the better the running-in quality. A multi-objective optimization design of the running-in parameters of the main bearing is carried out, using a non-dominated sorting genetic algorithm with elite strategy. The optimization targets are the large fractal dimension of friction coefficient, the large fractal dimension of wear surface, and small running-in time. It shows that the selection principles of running-in parameters are different for different stages and priorities. The optimal running-in parameters listed in this paper provides a specific reference to the optimal design of the three-stage running in of main bearing.","PeriodicalId":17586,"journal":{"name":"Journal of Tribology-transactions of The Asme","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2023-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46954165","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}
Liquid methane is one of the most promising candidates for the next-generation rocket propellant because it has an excellent balance between several propulsion performances such as specific impulse, storability, and structural coefficient. JAXA has developed rocket engine technologies for liquid methane engines. In this paper, we investigate heat generation characteristics of ball bearings used in liquid methane turbopumps. A usual approach to evaluate a cryogenic ball bearing performance is to conduct experimental testing which costs a lot. This research introduces numerical approaches based on physical mechanisms in rotating ball bearings to clarify the heat generation characteristics. The main factors of the heat generation are friction heat generation and fluid heat generation. The friction heat generation is caused by mechanical friction of bearing elements and calculated based on bearing motion analysis and Hertzian contact theory. The fluid heat generation is caused by the fluid drag force on bearing elements and calculated by CFD analysis. The theoretical model is compared with experimental results, showing an excellent agreement. It is clarified that the dominant factor of the bearing heat generation in liquid methane environment is the friction heat generation on races-balls contact at lower velocity condition while it tends to change to the fluid heat generation due to the bearing elements' rotational motion at higher velocity condition. In addition, cryogenic bearing characteristics which are clarified by theoretical modeling are discussed.
{"title":"Numerical Investigation of Turbopump Bearing Heat Generation in Liquid Methane","authors":"Hiromitsu Kakudo, S. Takada, T. Hirayama","doi":"10.1115/1.4062294","DOIUrl":"https://doi.org/10.1115/1.4062294","url":null,"abstract":"\u0000 Liquid methane is one of the most promising candidates for the next-generation rocket propellant because it has an excellent balance between several propulsion performances such as specific impulse, storability, and structural coefficient. JAXA has developed rocket engine technologies for liquid methane engines. In this paper, we investigate heat generation characteristics of ball bearings used in liquid methane turbopumps. A usual approach to evaluate a cryogenic ball bearing performance is to conduct experimental testing which costs a lot. This research introduces numerical approaches based on physical mechanisms in rotating ball bearings to clarify the heat generation characteristics. The main factors of the heat generation are friction heat generation and fluid heat generation. The friction heat generation is caused by mechanical friction of bearing elements and calculated based on bearing motion analysis and Hertzian contact theory. The fluid heat generation is caused by the fluid drag force on bearing elements and calculated by CFD analysis. The theoretical model is compared with experimental results, showing an excellent agreement. It is clarified that the dominant factor of the bearing heat generation in liquid methane environment is the friction heat generation on races-balls contact at lower velocity condition while it tends to change to the fluid heat generation due to the bearing elements' rotational motion at higher velocity condition. In addition, cryogenic bearing characteristics which are clarified by theoretical modeling are discussed.","PeriodicalId":17586,"journal":{"name":"Journal of Tribology-transactions of The Asme","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2023-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42634865","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}
Positron lifetime and electron backscatter diffraction studies were performed on pure vanadium samples subjected to the sliding test. The changes in the microstructure produced in this test are extending even to a depth of about 450 μm. As shown by the diffraction of electron backscattering, near this surface, just after starting the sliding test, a tribolayer with refinement randomly oriented grains is formed. The thickness of this layer varies from 8 to 19 μm depending on the sliding conditions and the mean grain size is about 0.2 μm. Its source is believed to be a continuous process of dynamic recrystallization. In this layer, the formation of cracks and debris is observed as well. Below is an intermediate layer with elongated grains and serrated grain boundaries in which a geometric dynamic recrystallization process has been recognized as well.
{"title":"Positron Annihilation and EBSD Studies of Subsurface Zone Created during Friction in Vanadium","authors":"J. Dryzek, M. Wróbel","doi":"10.1115/1.4062297","DOIUrl":"https://doi.org/10.1115/1.4062297","url":null,"abstract":"\u0000 Positron lifetime and electron backscatter diffraction studies were performed on pure vanadium samples subjected to the sliding test. The changes in the microstructure produced in this test are extending even to a depth of about 450 μm. As shown by the diffraction of electron backscattering, near this surface, just after starting the sliding test, a tribolayer with refinement randomly oriented grains is formed. The thickness of this layer varies from 8 to 19 μm depending on the sliding conditions and the mean grain size is about 0.2 μm. Its source is believed to be a continuous process of dynamic recrystallization. In this layer, the formation of cracks and debris is observed as well. Below is an intermediate layer with elongated grains and serrated grain boundaries in which a geometric dynamic recrystallization process has been recognized as well.","PeriodicalId":17586,"journal":{"name":"Journal of Tribology-transactions of The Asme","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2023-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48580289","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}
Yu Hou, Xi Wang, Xingyu Li, Rubing Guo, Junqiang Li, Qiang Li
The differences in the roller diameters within a roller bearing is unavoidable in practice, which is known as the off-sized effect. The off-sized effect results in the dynamic variation of the load distribution in bearings and further the abnormal vibration and premature failure of bearings. This paper experimentally investigates the effect of off-sized rollers on the dynamic load distribution in a cylindrical roller bearing. Different configurations of off-sized rollers are given considering the oversized and undersized roller conditions, and the number and position of off-sized rollers. The real-time roller-raceway contact loads distributed in the bearing are measured under these test cases. The results show that a single off-sized roller leads to the loading change directly on itself and further the load rebalances among the adjacent rollers. Under the conditions of multiple off-sized rollers, a stack effect of the competition rule of roller loading dominates the variation range of the dynamic load distribution. As results of the stack effect, among all roller configurations, the configuration of multiple off-sized rollers adjacent to each other leads to the minimum range of the dynamic load distribution, while the configuration of two off-sized rollers separated by a regular roller leads to the maximum one.
{"title":"Experimental Study on the Effect of Off-Sized Rollers on the Dynamic Load Distribution in a Cylindrical Roller Bearing","authors":"Yu Hou, Xi Wang, Xingyu Li, Rubing Guo, Junqiang Li, Qiang Li","doi":"10.1115/1.4062251","DOIUrl":"https://doi.org/10.1115/1.4062251","url":null,"abstract":"\u0000 The differences in the roller diameters within a roller bearing is unavoidable in practice, which is known as the off-sized effect. The off-sized effect results in the dynamic variation of the load distribution in bearings and further the abnormal vibration and premature failure of bearings. This paper experimentally investigates the effect of off-sized rollers on the dynamic load distribution in a cylindrical roller bearing. Different configurations of off-sized rollers are given considering the oversized and undersized roller conditions, and the number and position of off-sized rollers. The real-time roller-raceway contact loads distributed in the bearing are measured under these test cases. The results show that a single off-sized roller leads to the loading change directly on itself and further the load rebalances among the adjacent rollers. Under the conditions of multiple off-sized rollers, a stack effect of the competition rule of roller loading dominates the variation range of the dynamic load distribution. As results of the stack effect, among all roller configurations, the configuration of multiple off-sized rollers adjacent to each other leads to the minimum range of the dynamic load distribution, while the configuration of two off-sized rollers separated by a regular roller leads to the maximum one.","PeriodicalId":17586,"journal":{"name":"Journal of Tribology-transactions of The Asme","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2023-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49093254","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}
Ina Stratmann, J. Goersch, Moritz Neuser, C. Schindler, Tanja Stratmann
The contact zone between two steel components can be identified by utilizing a pressure measurement film in the contact between them. To reduce the number of necessary experiments, it is possible to simulate the contact situation using ‘finite element analysis’. This analysis requires material models for the contact partners and for the pressure measurement films. It is known that the pressure measurement film deforms not only elastically but also plastically. Taking this plastic deformation into account requires an appropriate material model such as the Drucker-Prager model. Based on published data of experiments with pressure measurement films that had been inserted between smooth and rough Hertzian bodies, we developed material models for three pressure measurement films. The roughness of a Hertzian body was studied by determining multiple pressure-clearance curves for three different surface roughnesses and for three different pressure measurement films. These curves were developed with micro models, which represented a small section of the rough contact surface. An average curve for each material was then implemented in the macro model for each roughness representing the contact situation. Subsequently, the resulting contact areas were compared with the published experimental data. This comparison showed that the material model for the smooth contact was able to emulate the experimentally determined contact areas. Including the pressure-clearance curves in the material model allowed the simulation of the rough contact situation. However, the deviation between the simulated and the experimental data was slightly larger for the rough surface than for the smooth surface.
{"title":"Developing elastic-plastic material models for pressure measurement films in a steel-steel contact for smooth and rough surfaces","authors":"Ina Stratmann, J. Goersch, Moritz Neuser, C. Schindler, Tanja Stratmann","doi":"10.1115/1.4062101","DOIUrl":"https://doi.org/10.1115/1.4062101","url":null,"abstract":"\u0000 The contact zone between two steel components can be identified by utilizing a pressure measurement film in the contact between them. To reduce the number of necessary experiments, it is possible to simulate the contact situation using ‘finite element analysis’. This analysis requires material models for the contact partners and for the pressure measurement films. It is known that the pressure measurement film deforms not only elastically but also plastically. Taking this plastic deformation into account requires an appropriate material model such as the Drucker-Prager model. Based on published data of experiments with pressure measurement films that had been inserted between smooth and rough Hertzian bodies, we developed material models for three pressure measurement films. The roughness of a Hertzian body was studied by determining multiple pressure-clearance curves for three different surface roughnesses and for three different pressure measurement films. These curves were developed with micro models, which represented a small section of the rough contact surface. An average curve for each material was then implemented in the macro model for each roughness representing the contact situation. Subsequently, the resulting contact areas were compared with the published experimental data. This comparison showed that the material model for the smooth contact was able to emulate the experimentally determined contact areas. Including the pressure-clearance curves in the material model allowed the simulation of the rough contact situation. However, the deviation between the simulated and the experimental data was slightly larger for the rough surface than for the smooth surface.","PeriodicalId":17586,"journal":{"name":"Journal of Tribology-transactions of The Asme","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2023-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42316260","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}
Materials wear is often characterized by empirical relations as the physical and chemical interactions at sliding interfaces are not fully understood at any length scale. Recent studies showed that these wear relations do not always hold in particular at the nanoscale. Here we discuss the validity range and limitations of two well-known wear models, i.e. Archard's and Reye's ones (which were principally developed for adhesive wear) for abrasive wear process. Using systematic long-timescale molecular dynamic nanoscratching simulations, we show that, at the nanoscale, the wear coefficient increases by the adhesion strength and scratching depth and eventually saturates to a constant value. The saturation is associated with the transition from atomic attrition wear mode to plasticity-induced wear. This new understanding rationalizes discrepant experimental observations on the validity of Archard's wear relation at the nanoscale. Furthermore, it confirms that a depth- and adhesion-independent wear coefficient can be obtained when plastic deformation dictates the abrasive wear process.
{"title":"On the uniqueness of wear coefficient for abrasive wear at nanoscale","authors":"Li Ma, R. Aghababaei","doi":"10.1115/1.4062099","DOIUrl":"https://doi.org/10.1115/1.4062099","url":null,"abstract":"\u0000 Materials wear is often characterized by empirical relations as the physical and chemical interactions at sliding interfaces are not fully understood at any length scale. Recent studies showed that these wear relations do not always hold in particular at the nanoscale. Here we discuss the validity range and limitations of two well-known wear models, i.e. Archard's and Reye's ones (which were principally developed for adhesive wear) for abrasive wear process. Using systematic long-timescale molecular dynamic nanoscratching simulations, we show that, at the nanoscale, the wear coefficient increases by the adhesion strength and scratching depth and eventually saturates to a constant value. The saturation is associated with the transition from atomic attrition wear mode to plasticity-induced wear. This new understanding rationalizes discrepant experimental observations on the validity of Archard's wear relation at the nanoscale. Furthermore, it confirms that a depth- and adhesion-independent wear coefficient can be obtained when plastic deformation dictates the abrasive wear process.","PeriodicalId":17586,"journal":{"name":"Journal of Tribology-transactions of The Asme","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2023-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44866224","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 recent years, cold spray additive manufacturing (CSAM) has become an attractive technology for surface modification and protection. However, due to the intrinsic porous nature of CSAM coatings, they suffer from rapid material degradation due to premature brittle fracturing induced by tribological interactions. In this work, laser shock peening (LSP) was utilized as a post-processing technology to mitigate the surface porosity and augment the surface characteristics of CSAM 316L SS. Due to the synergistic influence of severe plastic deformation and rapid surface heating, the surface porosities were effectively healed, thus reducing the surface roughness. Combined with the surface strengthening effects of LSP, the frictional resistance and transfer layer formation on the CSAM LSP surfaces were reduced. The underlying mechanisms for these findings were discussed by correlating the atomic, microstructural, and physical features of the LSP surfaces. Based on these findings, it can be suggested that LSP is indeed a useful technique to control the surface characteristics of CSAM 316L SS coatings.
{"title":"Tribological Performance of Laser Shock Peened Cold Spray Additive Manufactured 316L Stainless Steel","authors":"A. Ralls, B. Mao, P. Menezes","doi":"10.1115/1.4062102","DOIUrl":"https://doi.org/10.1115/1.4062102","url":null,"abstract":"\u0000 In recent years, cold spray additive manufacturing (CSAM) has become an attractive technology for surface modification and protection. However, due to the intrinsic porous nature of CSAM coatings, they suffer from rapid material degradation due to premature brittle fracturing induced by tribological interactions. In this work, laser shock peening (LSP) was utilized as a post-processing technology to mitigate the surface porosity and augment the surface characteristics of CSAM 316L SS. Due to the synergistic influence of severe plastic deformation and rapid surface heating, the surface porosities were effectively healed, thus reducing the surface roughness. Combined with the surface strengthening effects of LSP, the frictional resistance and transfer layer formation on the CSAM LSP surfaces were reduced. The underlying mechanisms for these findings were discussed by correlating the atomic, microstructural, and physical features of the LSP surfaces. Based on these findings, it can be suggested that LSP is indeed a useful technique to control the surface characteristics of CSAM 316L SS coatings.","PeriodicalId":17586,"journal":{"name":"Journal of Tribology-transactions of The Asme","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2023-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48567244","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}
E. Selvi, M. Kaba, F. Muhaffel, A. S. Vanlı, M. Baydoğan
Low wear resistance of AZ91 alloy is the main factor limiting its more common use in industrial applications. It is therefore the micro-arc oxidation (MAO) process is mostly applied to the alloy to improve its wear resistance at room temperature (RT). However, the effect of the MAO coating on the wear behaviour at elevated temperatures was investigated in limited works. In this study, the MAO process was performed on an AZ91 alloy in single-phase (silicate-containing) and dual-phase (aluminate+phosphate containing) electrolytes, and its wear behaviour was investigated at both RT and 200 °C compared to the bare alloy. The results showed that the wear resistance of the alloy could be significantly improved both at RT and 200 °C, and the silicate-based electrolyte provided a better wear resistance at both temperatures. The results also showed that the dominant wear mechanism was oxidation for the bare alloy, and brittle fracture for the MAO-treated alloys.
{"title":"Elevated Temperature Wear Behaviour of AZ91 Magnesium Alloy after Micro-Arc Oxidation in Single and Dual Phase Electrolytes","authors":"E. Selvi, M. Kaba, F. Muhaffel, A. S. Vanlı, M. Baydoğan","doi":"10.1115/1.4062100","DOIUrl":"https://doi.org/10.1115/1.4062100","url":null,"abstract":"\u0000 Low wear resistance of AZ91 alloy is the main factor limiting its more common use in industrial applications. It is therefore the micro-arc oxidation (MAO) process is mostly applied to the alloy to improve its wear resistance at room temperature (RT). However, the effect of the MAO coating on the wear behaviour at elevated temperatures was investigated in limited works. In this study, the MAO process was performed on an AZ91 alloy in single-phase (silicate-containing) and dual-phase (aluminate+phosphate containing) electrolytes, and its wear behaviour was investigated at both RT and 200 °C compared to the bare alloy. The results showed that the wear resistance of the alloy could be significantly improved both at RT and 200 °C, and the silicate-based electrolyte provided a better wear resistance at both temperatures. The results also showed that the dominant wear mechanism was oxidation for the bare alloy, and brittle fracture for the MAO-treated alloys.","PeriodicalId":17586,"journal":{"name":"Journal of Tribology-transactions of The Asme","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2023-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46549393","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}
To improve mechanical efficiency, the tribological performance of short period intermittent motion needs to be investigated. Based on the theory of thermal elastohydrodynamic lubrication (EHL) and considering the influences of rough surface, a mixed-EHL model under point contact simple sliding intermittent motion is established. Using this model, the transition from mixed-EHL to EHL in the contact area is realized by changing the period of intermittent motion and setting the surface roughness. It is found that the thermal effect in simple sliding intermittent motion should not be ignored, and the pressure, temperature rise distribution and friction coefficient during the stop and start-up are fluctuated obviously. Under the condition of rough surface contact, the contact area will enter the mixed-EHL state during the stop and start-up. Shortening the period of intermittent motion is beneficial to alleviate the adverse effect of the mixed-EHL.
{"title":"Point Contact Thermal Mixed-EHL under Short Period Intermittent Motion","authors":"Mingyu Zhang, Ming Yao, Jing Wang, Yong Wan","doi":"10.1115/1.4062098","DOIUrl":"https://doi.org/10.1115/1.4062098","url":null,"abstract":"\u0000 To improve mechanical efficiency, the tribological performance of short period intermittent motion needs to be investigated. Based on the theory of thermal elastohydrodynamic lubrication (EHL) and considering the influences of rough surface, a mixed-EHL model under point contact simple sliding intermittent motion is established. Using this model, the transition from mixed-EHL to EHL in the contact area is realized by changing the period of intermittent motion and setting the surface roughness. It is found that the thermal effect in simple sliding intermittent motion should not be ignored, and the pressure, temperature rise distribution and friction coefficient during the stop and start-up are fluctuated obviously. Under the condition of rough surface contact, the contact area will enter the mixed-EHL state during the stop and start-up. Shortening the period of intermittent motion is beneficial to alleviate the adverse effect of the mixed-EHL.","PeriodicalId":17586,"journal":{"name":"Journal of Tribology-transactions of The Asme","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2023-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41966527","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}
Yiming Han, P. Sperka, Jing Wang, I. Křupka, M. Hartl, Weimin Li, X. B. Wang, Weimin Liu
The influence of the grease-water two-phase emulsion on the bearing track on the film formation has been studied by carrying out optical interferometry experiments on a ball disk test rig to observe the dynamic film-forming behavior of lubricating grease under steady-state and micro-oscillation conditions. It is found that free water cause a brief rise in the grease film under steady-state conditions, specifically due to the grease-water phase connecting the oil band on both sides of the oil reservoir. The experiment determines that the state of the phase before entering the elastohydrodynamic lubrication (EHL) contact is water-in-oil. For the reciprocating motion and oscillation, the effects of the amount of free water and the length of the motion stroke are discussed in detail. It is found that for reciprocating movements with long stroke lengths, the effect of free water is summarized to enhance the fluidity of the fibrous mass of the grease thickener in the first few cycles of the movement. For shorter stroke lengths, the effect of free water is a scouring effect on the contact zone grease after 100 cycles. This paper provides new insights into the effects that causes water pollution to the point contact lubrication during the transformation from reciprocating motion to fretting.
{"title":"Influence of free water droplets on film formation under point contact grease lubrication","authors":"Yiming Han, P. Sperka, Jing Wang, I. Křupka, M. Hartl, Weimin Li, X. B. Wang, Weimin Liu","doi":"10.1115/1.4056944","DOIUrl":"https://doi.org/10.1115/1.4056944","url":null,"abstract":"\u0000 The influence of the grease-water two-phase emulsion on the bearing track on the film formation has been studied by carrying out optical interferometry experiments on a ball disk test rig to observe the dynamic film-forming behavior of lubricating grease under steady-state and micro-oscillation conditions. It is found that free water cause a brief rise in the grease film under steady-state conditions, specifically due to the grease-water phase connecting the oil band on both sides of the oil reservoir. The experiment determines that the state of the phase before entering the elastohydrodynamic lubrication (EHL) contact is water-in-oil. For the reciprocating motion and oscillation, the effects of the amount of free water and the length of the motion stroke are discussed in detail. It is found that for reciprocating movements with long stroke lengths, the effect of free water is summarized to enhance the fluidity of the fibrous mass of the grease thickener in the first few cycles of the movement. For shorter stroke lengths, the effect of free water is a scouring effect on the contact zone grease after 100 cycles. This paper provides new insights into the effects that causes water pollution to the point contact lubrication during the transformation from reciprocating motion to fretting.","PeriodicalId":17586,"journal":{"name":"Journal of Tribology-transactions of The Asme","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2023-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47728387","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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