Bhagwan Singh Lovevanshi, P. K. Soni, Savita Dixit
Abstract This research work aims to synthesis hybrid Al7075 metal matrix composite reinforced with sustainable and synthetic reinforcement. With the employment of an ultrasonic transducer, two stage stir-casting is used to synthesis composite materials. The prepared samples were machined and polished for mechanical, tribological, and microstructural characterization. Optical microscopy and Field emission scanning electron microscopy with elemental mapping were used to analyses the microstructure of the composite material. The microstructural examination revealed the homogeneous dispersion of reinforcement particles throughout the matrix. With the incorporation of reinforcement, the synthesized composite's compressive strength and micro-hardness were both increased and highest values are found as to be 569.172 MPa and 178.86 HV respectively in one of the sample (B3 sample) as compared to as-cast Al7075 alloy. Tribological examination of composites samples shows that wear rate enhances with increase in content of reinforcement. Wear resistance of sample B3 is highest among all prepared composite samples. Wear debris, grooves, micro-cracks, and small pits were observed on the worn out surfaces of the samples by FESEM analysis.
{"title":"Experimental investigations on the development of hybrid metal matrix composite of Al7075 on microstructural, mechanical, and dry sliding aspects","authors":"Bhagwan Singh Lovevanshi, P. K. Soni, Savita Dixit","doi":"10.1115/1.4064020","DOIUrl":"https://doi.org/10.1115/1.4064020","url":null,"abstract":"Abstract This research work aims to synthesis hybrid Al7075 metal matrix composite reinforced with sustainable and synthetic reinforcement. With the employment of an ultrasonic transducer, two stage stir-casting is used to synthesis composite materials. The prepared samples were machined and polished for mechanical, tribological, and microstructural characterization. Optical microscopy and Field emission scanning electron microscopy with elemental mapping were used to analyses the microstructure of the composite material. The microstructural examination revealed the homogeneous dispersion of reinforcement particles throughout the matrix. With the incorporation of reinforcement, the synthesized composite's compressive strength and micro-hardness were both increased and highest values are found as to be 569.172 MPa and 178.86 HV respectively in one of the sample (B3 sample) as compared to as-cast Al7075 alloy. Tribological examination of composites samples shows that wear rate enhances with increase in content of reinforcement. Wear resistance of sample B3 is highest among all prepared composite samples. Wear debris, grooves, micro-cracks, and small pits were observed on the worn out surfaces of the samples by FESEM analysis.","PeriodicalId":17586,"journal":{"name":"Journal of Tribology-transactions of The Asme","volume":"86 S24","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135432709","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}
Xinqi Wang, Wei Sun, Lintao Wang, Shihu Liang, Xiaokai Mu
Abstract An optimal design method for the main bearing of a tunnel boring machine is proposed. In this method, the fatigue life is used as the objective function. Structural parameters, including clearance, are considered design variables. First, a quasi-static model of the main bearing and a calculation model of the fatigue life are established. The correctness of the theoretical method is verified by comparing it with the calculation results of the finite element method. Next, the influence of clearance on the load-carrying performance under external loads is analyzed. There is an optimal negative clearance for the axial loaded and radial rows. With the increase in the external loads, the optimal negative clearance gradually decreases. The variation laws of the load-carrying performance for the axial loaded and supporting rows affected by axial clearance mainly depend on the bias load degree of the main bearing. Finally, based on the optimal design model of the main bearing, the optimal internal structure is obtained using the genetic algorithm. The optimized fatigue life is improved by 92.2%. The load-carrying performance of the optimal main bearing has also been significantly enhanced compared to the initial design. Therefore, the proposed optimization method provides a practical approach to the main bearing design.
{"title":"Structural optimization of the main bearing in a tunnel boring machine considering clearance","authors":"Xinqi Wang, Wei Sun, Lintao Wang, Shihu Liang, Xiaokai Mu","doi":"10.1115/1.4064019","DOIUrl":"https://doi.org/10.1115/1.4064019","url":null,"abstract":"Abstract An optimal design method for the main bearing of a tunnel boring machine is proposed. In this method, the fatigue life is used as the objective function. Structural parameters, including clearance, are considered design variables. First, a quasi-static model of the main bearing and a calculation model of the fatigue life are established. The correctness of the theoretical method is verified by comparing it with the calculation results of the finite element method. Next, the influence of clearance on the load-carrying performance under external loads is analyzed. There is an optimal negative clearance for the axial loaded and radial rows. With the increase in the external loads, the optimal negative clearance gradually decreases. The variation laws of the load-carrying performance for the axial loaded and supporting rows affected by axial clearance mainly depend on the bias load degree of the main bearing. Finally, based on the optimal design model of the main bearing, the optimal internal structure is obtained using the genetic algorithm. The optimized fatigue life is improved by 92.2%. The load-carrying performance of the optimal main bearing has also been significantly enhanced compared to the initial design. Therefore, the proposed optimization method provides a practical approach to the main bearing design.","PeriodicalId":17586,"journal":{"name":"Journal of Tribology-transactions of The Asme","volume":"81 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135433430","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}
Changqing Miao, Bangying Xiong, Kang Yang, Na Xiao, Zihe Shao, Feizhi Zhang, Honglei Zhang, Yahui Xiong, Jun Tang, Hao Chen
Abstract Nonrenewable energy has produced abundant waste during tribological applications because a large portion of energy has been consumed to overcome friction and wear. Solid lubricants have recently aroused significant interest due to their defined friction and wear properties. Despite enormous efforts on solid lubricants, their important contributions to coatings, bulk materials, oil/grease, and super-lubricity have not yet been fully evaluated. This paper discusses in detail the present status of solid lubricants as effective reinforcements in tribology. It begins with the introduction of various descriptions and advanced structures of solid lubricants. Afterwards, it discussed their applications on improving friction properties in coatings and bulk materials. Additionally, lubrication mechanisms of solid lubricants in oil/grease are highlighted, followed by the detailed discussion of super-lubricity for solid lubricants. Finally, this review concludes final outlooks on the main challenges and future directions in this key area.
{"title":"Recent progress on the tribological applications of solid lubricants","authors":"Changqing Miao, Bangying Xiong, Kang Yang, Na Xiao, Zihe Shao, Feizhi Zhang, Honglei Zhang, Yahui Xiong, Jun Tang, Hao Chen","doi":"10.1115/1.4063701","DOIUrl":"https://doi.org/10.1115/1.4063701","url":null,"abstract":"Abstract Nonrenewable energy has produced abundant waste during tribological applications because a large portion of energy has been consumed to overcome friction and wear. Solid lubricants have recently aroused significant interest due to their defined friction and wear properties. Despite enormous efforts on solid lubricants, their important contributions to coatings, bulk materials, oil/grease, and super-lubricity have not yet been fully evaluated. This paper discusses in detail the present status of solid lubricants as effective reinforcements in tribology. It begins with the introduction of various descriptions and advanced structures of solid lubricants. Afterwards, it discussed their applications on improving friction properties in coatings and bulk materials. Additionally, lubrication mechanisms of solid lubricants in oil/grease are highlighted, followed by the detailed discussion of super-lubricity for solid lubricants. Finally, this review concludes final outlooks on the main challenges and future directions in this key area.","PeriodicalId":17586,"journal":{"name":"Journal of Tribology-transactions of The Asme","volume":"61 11","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135874126","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}
Abstract A systematic process of matrices-based wear profile modeling and a new optimization approach for planetary roller screw mechanism (PRSM) was proposed in this paper to improve the anti-wear performance with varied thread geometries. The wear evolution characteristics of thread surfaces for convex–concave contact and convex–straight contact were captured by incorporating updated axial clearances originated from accumulated thread wear, which provides a new perspective to predict the wear process of PRSM. The results show that the wear depth in convex–concave contact is 22% shallower than convex–straight contact with 105 numbers of cycles, which suggests thread wear can be limited with plausible geometrical parameters. Further analysis showed that as the surface roughness increases, the true equivalent pressure, the plastic strain, and the maximum wear depth become larger. In addition, the effect of the surface textures on the tribological properties of threads is also discussed to improve the applicability of the proposed methodology.
{"title":"Improved wear profile modelling of planetary roller screw mechanism with thread optimization","authors":"Jiacheng Miao, Xing Du, Chaoyang Li, Bingkui Chen","doi":"10.1115/1.4063703","DOIUrl":"https://doi.org/10.1115/1.4063703","url":null,"abstract":"Abstract A systematic process of matrices-based wear profile modeling and a new optimization approach for planetary roller screw mechanism (PRSM) was proposed in this paper to improve the anti-wear performance with varied thread geometries. The wear evolution characteristics of thread surfaces for convex–concave contact and convex–straight contact were captured by incorporating updated axial clearances originated from accumulated thread wear, which provides a new perspective to predict the wear process of PRSM. The results show that the wear depth in convex–concave contact is 22% shallower than convex–straight contact with 105 numbers of cycles, which suggests thread wear can be limited with plausible geometrical parameters. Further analysis showed that as the surface roughness increases, the true equivalent pressure, the plastic strain, and the maximum wear depth become larger. In addition, the effect of the surface textures on the tribological properties of threads is also discussed to improve the applicability of the proposed methodology.","PeriodicalId":17586,"journal":{"name":"Journal of Tribology-transactions of The Asme","volume":"62 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135874124","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}
Abstract In this study, the tribological properties of the mixture of nano magnesium silicate hydroxide (MSH) and micro carbon sphere (CS) are studied, and a superior synergistic anti-wear performance is exhibited under 600 N and 600 RPM. For determining the anti-wear mechanism, an easy two-step experimental method is innovatively used. It is proved that the decomposition of MSH is the key to exhibit the synergistic anti-wear effect with amorphous carbon (a-C). Results show that the H+ protons released by MSH decomposition can effectively convert Fe2O3 to Fe3O4 on worn surfaces. Besides, MSH also helps the formed a-C layer exist in low H content with stronger adhesion on the iron surface, and the detached H atoms from C–H further facilitate the reduction of Fe2O3. It is believed that the critical role of lamellate clay in synergy with a-C as a lubricant additive is determined, and a basis for the further anti-wear mechanism study of various a-C-modified clay composite is provided.
{"title":"Nano Magnesium silicate hydroxide as synergistic lubricant additive with micro carbon sphere for enhanced tribological properties","authors":"Rongqin Gao, Qiuying Chang, Hao Lichun, Yang He","doi":"10.1115/1.4063702","DOIUrl":"https://doi.org/10.1115/1.4063702","url":null,"abstract":"Abstract In this study, the tribological properties of the mixture of nano magnesium silicate hydroxide (MSH) and micro carbon sphere (CS) are studied, and a superior synergistic anti-wear performance is exhibited under 600 N and 600 RPM. For determining the anti-wear mechanism, an easy two-step experimental method is innovatively used. It is proved that the decomposition of MSH is the key to exhibit the synergistic anti-wear effect with amorphous carbon (a-C). Results show that the H+ protons released by MSH decomposition can effectively convert Fe2O3 to Fe3O4 on worn surfaces. Besides, MSH also helps the formed a-C layer exist in low H content with stronger adhesion on the iron surface, and the detached H atoms from C–H further facilitate the reduction of Fe2O3. It is believed that the critical role of lamellate clay in synergy with a-C as a lubricant additive is determined, and a basis for the further anti-wear mechanism study of various a-C-modified clay composite is provided.","PeriodicalId":17586,"journal":{"name":"Journal of Tribology-transactions of The Asme","volume":"61 12","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135874125","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 present study investigates the effect of friction parameters on tribological properties of erucamide as an additive in grease on GCr15 steel, as well as the sensitivity of erucamide to these parameters. An orthogonal test design is utilized to sample the friction parameters, followed by the construction of a Kriging model to articulate the relationship between these parameters and the designated objectives (average friction coefficient and wear volume). The Non-dominated Sorting Genetic Algorithm II (NSGA-II) is used to optimize the design objectives and verify the accuracy of the model. Monte Carlo method is used to analyze the sensitivity of erucamide to the friction parameters. The results showed that erucamide exhibite excellent tribological properties at 80N/20Hz/25°C and 20N/20Hz/25°C. The sensitivity of erucamide to friction parameters from high to low is temperature, load and speed. This can be ascribed to erucamide's unique structure, encompassing a globular aggregation head and a hydrophobic tail extending outward. The anti-friction effects and lubrication properties of erucamide are driven by its rheological properties and intermolecular interactions. At elevated temperatures, erucamide's fluidity escalates, favoring the lubricating film formation; however, excessive fluidity may impede its adherence to requisite locations, thereby resulting in compromised tribological properties of erucamide at high temperatures.
{"title":"Effect of Friction Parameters on Tribological Properties of Erucamide as Grease Additive on GCr15 Steel","authors":"Qingchun Liu, YiMin Mo","doi":"10.1115/1.4063810","DOIUrl":"https://doi.org/10.1115/1.4063810","url":null,"abstract":"The present study investigates the effect of friction parameters on tribological properties of erucamide as an additive in grease on GCr15 steel, as well as the sensitivity of erucamide to these parameters. An orthogonal test design is utilized to sample the friction parameters, followed by the construction of a Kriging model to articulate the relationship between these parameters and the designated objectives (average friction coefficient and wear volume). The Non-dominated Sorting Genetic Algorithm II (NSGA-II) is used to optimize the design objectives and verify the accuracy of the model. Monte Carlo method is used to analyze the sensitivity of erucamide to the friction parameters. The results showed that erucamide exhibite excellent tribological properties at 80N/20Hz/25°C and 20N/20Hz/25°C. The sensitivity of erucamide to friction parameters from high to low is temperature, load and speed. This can be ascribed to erucamide's unique structure, encompassing a globular aggregation head and a hydrophobic tail extending outward. The anti-friction effects and lubrication properties of erucamide are driven by its rheological properties and intermolecular interactions. At elevated temperatures, erucamide's fluidity escalates, favoring the lubricating film formation; however, excessive fluidity may impede its adherence to requisite locations, thereby resulting in compromised tribological properties of erucamide at high temperatures.","PeriodicalId":17586,"journal":{"name":"Journal of Tribology-transactions of The Asme","volume":"54 2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135874957","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}
Abstract The height probability distribution (HPD) of random rough surface topography has significant effect on its contact behaviors. In this paper, an optimization model to calculate the optimal HPD of random rough surface topography to make its contact force-deformation characteristic satisfy the given target force-deformation characteristic was established. In the solution to calculate the optimal HPD, using Bezier interpolation curve to represent the curve of HPD function and using the positions of the control points of Bezier interpolation curve as optimization variables were proposed. The solution was validated by numerical simulations implemented using MATLAB. The effect of the number of the control points on the minimum objective function value was investigated. Through analyzing the obtained result, we found the most appropriate number of the control points is 35. Comparison with the method using height parameters as optimization variables in literature was implemented. It was found that the proposed method is applicable to broader types of contact force-deformation characteristic requirements than the method using height parameters as optimization variables.
{"title":"A Novel Method of Designing Random Rough Surface Considering Its Contact Force-Deformation Characteristic Requirement","authors":"Xuxin Guo, Daxin Liu, Zhenyu Liu, Jianrong Tan","doi":"10.1115/1.4063946","DOIUrl":"https://doi.org/10.1115/1.4063946","url":null,"abstract":"Abstract The height probability distribution (HPD) of random rough surface topography has significant effect on its contact behaviors. In this paper, an optimization model to calculate the optimal HPD of random rough surface topography to make its contact force-deformation characteristic satisfy the given target force-deformation characteristic was established. In the solution to calculate the optimal HPD, using Bezier interpolation curve to represent the curve of HPD function and using the positions of the control points of Bezier interpolation curve as optimization variables were proposed. The solution was validated by numerical simulations implemented using MATLAB. The effect of the number of the control points on the minimum objective function value was investigated. Through analyzing the obtained result, we found the most appropriate number of the control points is 35. Comparison with the method using height parameters as optimization variables in literature was implemented. It was found that the proposed method is applicable to broader types of contact force-deformation characteristic requirements than the method using height parameters as optimization variables.","PeriodicalId":17586,"journal":{"name":"Journal of Tribology-transactions of The Asme","volume":"112 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136104456","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}
Abstract The empirical and mathematical approach is presented in the present paper for multiple distributed and localized flaws analyses in the shaft-rotor-bearing arrangement. These flaws in the combination of inner raceway, outer raceway, and roller are measured for the analysis. To comprehend their relevance and how they affect the vibration response for the shaft-rotor-bearing mechanism, speed, load, and flaws were regarded to be the crucial process factors in this investigation. The Full Factorial method was considered for experimentation, and the experiment was done with the design of experiments (DOE) methodology. The outcomes of the vibration response trials are quantified as Root Mean Square (RMS) values for interpretation. To determine the relationship between the effects of changing process parameters onto the response of vibrations, response surface methodology (RSM) is applied. DOE is used to examine the shaft-rotor-bearing test arrangement, which is employed for exploration. In the present research, it is established how combined parametric effect analysis predicts faults in the shaft-rotor-bearing system and how it affects DOE and RSM.
{"title":"Experimental Vibration Investigation of Roller Element Bearing with Combined Faults using Response Surface Methodology","authors":"Samruddhi Patel, Sanjay Patel","doi":"10.1115/1.4063947","DOIUrl":"https://doi.org/10.1115/1.4063947","url":null,"abstract":"Abstract The empirical and mathematical approach is presented in the present paper for multiple distributed and localized flaws analyses in the shaft-rotor-bearing arrangement. These flaws in the combination of inner raceway, outer raceway, and roller are measured for the analysis. To comprehend their relevance and how they affect the vibration response for the shaft-rotor-bearing mechanism, speed, load, and flaws were regarded to be the crucial process factors in this investigation. The Full Factorial method was considered for experimentation, and the experiment was done with the design of experiments (DOE) methodology. The outcomes of the vibration response trials are quantified as Root Mean Square (RMS) values for interpretation. To determine the relationship between the effects of changing process parameters onto the response of vibrations, response surface methodology (RSM) is applied. DOE is used to examine the shaft-rotor-bearing test arrangement, which is employed for exploration. In the present research, it is established how combined parametric effect analysis predicts faults in the shaft-rotor-bearing system and how it affects DOE and RSM.","PeriodicalId":17586,"journal":{"name":"Journal of Tribology-transactions of The Asme","volume":"5 2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136104788","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}
Abstract A thrust bearing is a rotary bearing that facilitates rotational movement between components and is specifically engineered to provide support for a load that is parallel to the axis of rotation. The generation of the inter-surface film pressure is attributed to the relative motion (rotation) of the surfaces, which results in the lubricant being drawn into the converging wedge formed between them. The interface between the unmovable and moving parts is demarcated by a slender layer of lubricating fluid, including but not limited to oil, water, air, or other process fluid. The conventional zero-equation model can be enhanced to achieve higher precision in forecasting and reduce dependence on empirical data, owing to its inherent limitations. A novel turbulence model that combines zero-equation and one-equation approaches has been developed and implemented in the recently introduced modeling tool package for thrust bearings. In the Prandtl one-equation turbulence model, the length scale is a necessary but undetermined term. A novel mixed model has been implemented utilizing the Prandtl one equation along with a novel length scale. The tool package is a Thermo-hydrodynamic (THD) code that involves iterative computations between the Reynolds' equation, turbulence equation, energy equation within the film, and conduction equation in pad and runner. The new model yields an eddy viscosity that exhibits a substantial level of proximity to both Eddy Viscosity Transport (EVT) and Direct Numerical Simulation (DNS), and exhibits significant enhancements in comparison to the traditional Ng-Pan zero-equation turbulence model.
{"title":"A Mixed Zero-equation and One-equation Turbulence Model in Fluid-film Thrust Bearings","authors":"Xin Deng","doi":"10.1115/1.4063945","DOIUrl":"https://doi.org/10.1115/1.4063945","url":null,"abstract":"Abstract A thrust bearing is a rotary bearing that facilitates rotational movement between components and is specifically engineered to provide support for a load that is parallel to the axis of rotation. The generation of the inter-surface film pressure is attributed to the relative motion (rotation) of the surfaces, which results in the lubricant being drawn into the converging wedge formed between them. The interface between the unmovable and moving parts is demarcated by a slender layer of lubricating fluid, including but not limited to oil, water, air, or other process fluid. The conventional zero-equation model can be enhanced to achieve higher precision in forecasting and reduce dependence on empirical data, owing to its inherent limitations. A novel turbulence model that combines zero-equation and one-equation approaches has been developed and implemented in the recently introduced modeling tool package for thrust bearings. In the Prandtl one-equation turbulence model, the length scale is a necessary but undetermined term. A novel mixed model has been implemented utilizing the Prandtl one equation along with a novel length scale. The tool package is a Thermo-hydrodynamic (THD) code that involves iterative computations between the Reynolds' equation, turbulence equation, energy equation within the film, and conduction equation in pad and runner. The new model yields an eddy viscosity that exhibits a substantial level of proximity to both Eddy Viscosity Transport (EVT) and Direct Numerical Simulation (DNS), and exhibits significant enhancements in comparison to the traditional Ng-Pan zero-equation turbulence model.","PeriodicalId":17586,"journal":{"name":"Journal of Tribology-transactions of The Asme","volume":"719 ","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136067919","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}
Abstract In the traditional elastohydrodynamic lubrication (EHL) field, surface elastic deformation is usually determined using an elastic half-space model for isotropic materials. However, this theory may be inefficient when applied to point contact problems involving inherently anisotropic materials, such as transversely isotropic (TI) materials. Accordingly, the present study proposes a method for solving the EHL point contact problem between a rigid ball and a TI substrate under impact loading using a direct-solving numerical method, in which the mechanical properties of the TI material are expressed in the form of a stiffness matrix. For comparison purposes, the TI material is also approximated as an isotropic material using Turner’s approximation method based on the equivalent modulus property of the material. It is found that the direct-solving method outperforms Turner’s approximation in interpreting the mechanical properties of the TI substrate. In addition, it is shown that the initial velocity of the rigid ball and the stiffness of the TI material (i.e., the transverse elastic modulus, longitudinal modulus, and shear modulus) have significant effects on the load, impact velocity, and acceleration of the ball; central pressure and film thickness of the lubricant; and deformation and von Mises stress of the TI substrate, during the impact process. Overall, the results show that the proposed EHL model provides a useful tool for solving impact-EHL problems involving TI materials.
{"title":"Impact elastohydrodynamic lubrication analysis of transversely isotropic materials in point contact","authors":"Linh Thi Phuong Nguyen, Wang-Long Li","doi":"10.1115/1.4063496","DOIUrl":"https://doi.org/10.1115/1.4063496","url":null,"abstract":"Abstract In the traditional elastohydrodynamic lubrication (EHL) field, surface elastic deformation is usually determined using an elastic half-space model for isotropic materials. However, this theory may be inefficient when applied to point contact problems involving inherently anisotropic materials, such as transversely isotropic (TI) materials. Accordingly, the present study proposes a method for solving the EHL point contact problem between a rigid ball and a TI substrate under impact loading using a direct-solving numerical method, in which the mechanical properties of the TI material are expressed in the form of a stiffness matrix. For comparison purposes, the TI material is also approximated as an isotropic material using Turner’s approximation method based on the equivalent modulus property of the material. It is found that the direct-solving method outperforms Turner’s approximation in interpreting the mechanical properties of the TI substrate. In addition, it is shown that the initial velocity of the rigid ball and the stiffness of the TI material (i.e., the transverse elastic modulus, longitudinal modulus, and shear modulus) have significant effects on the load, impact velocity, and acceleration of the ball; central pressure and film thickness of the lubricant; and deformation and von Mises stress of the TI substrate, during the impact process. Overall, the results show that the proposed EHL model provides a useful tool for solving impact-EHL problems involving TI materials.","PeriodicalId":17586,"journal":{"name":"Journal of Tribology-transactions of The Asme","volume":"74 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135667257","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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