Micro-scale gas lubrication has been studied for several decades, with extensive research on non-equilibrium flow effects like velocity slip and thermal creep. However, the Knudsen maximum effect in micro-scale gas lubrication has not been reported yet. To address this, we analyzed the load capacity characteristics of slider bearings with ultra-thin film gas lubrication equations derived from the linearized Boltzmann-BGK model equation (FK lubrication model) under the condition of constant bearing number. Our study reveals that there exists a maximum value of load capacity for slider bearings when the reference Knudsen number is about unity. This happens because the dimensionless mass flow rate of micro-scale gas flows has a minimum value when the reference Knudsen number approaches unity. Understanding the Knudsen maximum effect is crucial when designing micro-nano devices related to gas lubrication, as it implies that there exists an optimum clearance for maximum load capacity.
{"title":"Knudsen Maximum Effect in Micro-Scale Gas Lubrication","authors":"Haijun Zhang, X. Gu, Qin Yang, Wei Zhao, Feilong Jiang","doi":"10.1115/1.4063268","DOIUrl":"https://doi.org/10.1115/1.4063268","url":null,"abstract":"\u0000 Micro-scale gas lubrication has been studied for several decades, with extensive research on non-equilibrium flow effects like velocity slip and thermal creep. However, the Knudsen maximum effect in micro-scale gas lubrication has not been reported yet. To address this, we analyzed the load capacity characteristics of slider bearings with ultra-thin film gas lubrication equations derived from the linearized Boltzmann-BGK model equation (FK lubrication model) under the condition of constant bearing number. Our study reveals that there exists a maximum value of load capacity for slider bearings when the reference Knudsen number is about unity. This happens because the dimensionless mass flow rate of micro-scale gas flows has a minimum value when the reference Knudsen number approaches unity. Understanding the Knudsen maximum effect is crucial when designing micro-nano devices related to gas lubrication, as it implies that there exists an optimum clearance for maximum load capacity.","PeriodicalId":17586,"journal":{"name":"Journal of Tribology-transactions of The Asme","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2023-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49465430","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}
Roller skew in roller bearings can cause heat generation in roller-race and roller-rib contacts, thus reducing bearing life. It is significant to obtain the roller skew angle in situ for guiding the bearing design and adjusting the operating conditions. In this study, a method for measuring the roller skew angle in the loading zone of a cylindrical roller bearing with strain gauges is presented. The measurement principle is that the roller skew angle is related to the movement of the contact line between the roller and raceway. The strain gauge array on the outer surface of the outer ring shows temporally separated responses when roller skew occurs. An experimental system is developed to validate the effectiveness of the proposed method for cylindrical roller bearing measurements. A laser measurement system is incorporated into the experimental system to detect the horizontal displacement of the reflected spot using a high-speed camera, which is then converted into the roller skew angle. The calculated roller skew angle from the time shift of the strain response agrees well with the value of a specially modified roller independently measured with the laser detection system. Compared with other measurement methods, the proposed method provides a potential way to achieve the nondestructive measurement of the roller skew angle in actual service for long-term purposes.
{"title":"Measuring the roller skew angle in the loading zone of a cylindrical roller bearing with strain gauges for long-term monitoring","authors":"Zhixiang Zhao, Xi Wang, Yu Hou","doi":"10.1115/1.4063211","DOIUrl":"https://doi.org/10.1115/1.4063211","url":null,"abstract":"\u0000 Roller skew in roller bearings can cause heat generation in roller-race and roller-rib contacts, thus reducing bearing life. It is significant to obtain the roller skew angle in situ for guiding the bearing design and adjusting the operating conditions. In this study, a method for measuring the roller skew angle in the loading zone of a cylindrical roller bearing with strain gauges is presented. The measurement principle is that the roller skew angle is related to the movement of the contact line between the roller and raceway. The strain gauge array on the outer surface of the outer ring shows temporally separated responses when roller skew occurs. An experimental system is developed to validate the effectiveness of the proposed method for cylindrical roller bearing measurements. A laser measurement system is incorporated into the experimental system to detect the horizontal displacement of the reflected spot using a high-speed camera, which is then converted into the roller skew angle. The calculated roller skew angle from the time shift of the strain response agrees well with the value of a specially modified roller independently measured with the laser detection system. Compared with other measurement methods, the proposed method provides a potential way to achieve the nondestructive measurement of the roller skew angle in actual service for long-term purposes.","PeriodicalId":17586,"journal":{"name":"Journal of Tribology-transactions of The Asme","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2023-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47644326","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}
Determining the friction and wear behaviors of aero-engine key components under realistic conditions is important to improve their long-term reliability and service life. In this paper, the friction and wear behaviors of different bushing materials in the variable stator vane (VSV) system were investigated through the basic pin-on-disc test and actual shaft-bushing test, and different machine learning (ML) models were established based on the experimental information to predict the coefficient of friction (COF) and wear rate. The results indicated that there is a significant temperature warning line for the wear amount of the polymer material, while the superalloy material exhibited stable tribological performance under experimental load and temperature conditions. ML analysis indicated that the eXtreme Gradient Boosting (XGB) outperformed other ML algorithms in predicting the COF (R-square value = 0.956), while the Kernel Ridge Regression (KRR) produced the best performance for predicting the wear rate (R-square value = 0.997). The tribo-informatics research for bushings in the VSV system can accelerate the structural optimization and material selection, and support the evaluation of new structures and materials.
{"title":"Tribo-informatics Approach to Investigate the Friction and Wear of Bushings in the Variable Stator Vane System","authors":"Ke He, Yufei Ma, Zhinan Zhang","doi":"10.1115/1.4063186","DOIUrl":"https://doi.org/10.1115/1.4063186","url":null,"abstract":"\u0000 Determining the friction and wear behaviors of aero-engine key components under realistic conditions is important to improve their long-term reliability and service life. In this paper, the friction and wear behaviors of different bushing materials in the variable stator vane (VSV) system were investigated through the basic pin-on-disc test and actual shaft-bushing test, and different machine learning (ML) models were established based on the experimental information to predict the coefficient of friction (COF) and wear rate. The results indicated that there is a significant temperature warning line for the wear amount of the polymer material, while the superalloy material exhibited stable tribological performance under experimental load and temperature conditions. ML analysis indicated that the eXtreme Gradient Boosting (XGB) outperformed other ML algorithms in predicting the COF (R-square value = 0.956), while the Kernel Ridge Regression (KRR) produced the best performance for predicting the wear rate (R-square value = 0.997). The tribo-informatics research for bushings in the VSV system can accelerate the structural optimization and material selection, and support the evaluation of new structures and materials.","PeriodicalId":17586,"journal":{"name":"Journal of Tribology-transactions of The Asme","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2023-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44347515","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}
Bulk flow models for grooved annular seals provide computationally efficient static and dynamic response predictions, though heavy reliance on empirical relationships often leads to undesirable levels of uncertainty. The flow complexity caused by the grooves adds difficulty to shear stress modeling for these seals. This study seeks to improve shear stress modeling for grooved seals through the identification and quantification of the additional bulk flow shear stress contributions within the groove region. Through single groove computational fluid dynamics (CFD) simulations and an effective film thickness analysis framework, the additional groove shear stress component is identified as a form shear stress (FSS) due to its clear relationship to the effective film thickness behavior. The FSS is quantified as a correction to traditional shear stress definitions. Predictive models for the FSS are developed as functions of the ratio of circumferential to axial Reynolds number and the total resultant Reynolds number. Implementation of the FSS models into a simplified bulk flow method delivers leakage predictions for three seal cases within 10% of the experimental results and qualitative agreement in predicted circumferential velocity profiles while eliminating the need for an assumed groove loss coefficient. This is the first paper to utilize an effective film thickness based procedure to quantify and model the FSS component in grooved seal bulk flow analysis. The demonstrated predictive capability and widespread applicability of the models and approach presented in this paper provide an avenue for significant improvements in grooved seal bulk flow prediction accuracy through improved shear stress modeling.
{"title":"Form Shear Stress (FSS) Correction in Bulk Flow Analysis of Grooved Seals Based on Effective Film Thickness","authors":"Nathaniel P Gibbons, C. Goyne","doi":"10.1115/1.4063190","DOIUrl":"https://doi.org/10.1115/1.4063190","url":null,"abstract":"\u0000 Bulk flow models for grooved annular seals provide computationally efficient static and dynamic response predictions, though heavy reliance on empirical relationships often leads to undesirable levels of uncertainty. The flow complexity caused by the grooves adds difficulty to shear stress modeling for these seals. This study seeks to improve shear stress modeling for grooved seals through the identification and quantification of the additional bulk flow shear stress contributions within the groove region. Through single groove computational fluid dynamics (CFD) simulations and an effective film thickness analysis framework, the additional groove shear stress component is identified as a form shear stress (FSS) due to its clear relationship to the effective film thickness behavior. The FSS is quantified as a correction to traditional shear stress definitions. Predictive models for the FSS are developed as functions of the ratio of circumferential to axial Reynolds number and the total resultant Reynolds number. Implementation of the FSS models into a simplified bulk flow method delivers leakage predictions for three seal cases within 10% of the experimental results and qualitative agreement in predicted circumferential velocity profiles while eliminating the need for an assumed groove loss coefficient. This is the first paper to utilize an effective film thickness based procedure to quantify and model the FSS component in grooved seal bulk flow analysis. The demonstrated predictive capability and widespread applicability of the models and approach presented in this paper provide an avenue for significant improvements in grooved seal bulk flow prediction accuracy through improved shear stress modeling.","PeriodicalId":17586,"journal":{"name":"Journal of Tribology-transactions of The Asme","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2023-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42831071","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}
As an advanced sealing technology, the application of gas face seal in aero-engine is few, if possible, lower specific fuel consumption, higher thrust-weight ratio, and effective secondary flow control at minimal cost would be brought. A Relative Negative Pressure Zone (RNPZ) was found in the spiral groove gas face seal, and the evolution and action mechanism of RNPZ was investigated in detail, which may promote the above application. Three film thicknesses of spiral groove gas face seals at different rotational speeds and inlet pressures were numerically compared to obtain the pressure field in the groove area and the formation of RNPZ. Then, the radial and circumferential velocities in the groove were calculated to quantify the impact of the obstruction effect, viscous pumping, and shear effect, which revealed the evolution mechanism of the RNPZ stage by stage. At last, the action mechanism of RNPZ was clarified through the hydrodynamic performance analysis. It is found that the pressure field evolution in the gas face seal is in stage three under the high rotational speed and low inlet pressure conditions in an aero-engine. Under the same film thickness, RNPZ can suppress leakage to a certain extent in stage two, while in stage three, it increases the opening force and stiffness-leakage ratio. This work can provide theory and data to help with the subsequent optimization design of gas-face seals for aero-engine.
{"title":"Evolution and action mechanism of relative negative pressure zone in spiral groove gas face seal for aero-engine","authors":"Hui Li, Guoqi Li, Hao Liu, Ang Li, Xin'gen Lu","doi":"10.1115/1.4063197","DOIUrl":"https://doi.org/10.1115/1.4063197","url":null,"abstract":"\u0000 As an advanced sealing technology, the application of gas face seal in aero-engine is few, if possible, lower specific fuel consumption, higher thrust-weight ratio, and effective secondary flow control at minimal cost would be brought. A Relative Negative Pressure Zone (RNPZ) was found in the spiral groove gas face seal, and the evolution and action mechanism of RNPZ was investigated in detail, which may promote the above application. Three film thicknesses of spiral groove gas face seals at different rotational speeds and inlet pressures were numerically compared to obtain the pressure field in the groove area and the formation of RNPZ. Then, the radial and circumferential velocities in the groove were calculated to quantify the impact of the obstruction effect, viscous pumping, and shear effect, which revealed the evolution mechanism of the RNPZ stage by stage. At last, the action mechanism of RNPZ was clarified through the hydrodynamic performance analysis. It is found that the pressure field evolution in the gas face seal is in stage three under the high rotational speed and low inlet pressure conditions in an aero-engine. Under the same film thickness, RNPZ can suppress leakage to a certain extent in stage two, while in stage three, it increases the opening force and stiffness-leakage ratio. This work can provide theory and data to help with the subsequent optimization design of gas-face seals for aero-engine.","PeriodicalId":17586,"journal":{"name":"Journal of Tribology-transactions of The Asme","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2023-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41958976","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 explores the reinforcement effects of both boron nitride nanotubes (BNNTs) and micro-boron carbide (μB4C) on the tribological and mechanical properties of aluminum matrix composite (MMC) cold-sprayed coatings. The synthesis process involved high energy ball milling (HEBM) and cold spraying with helium to create four distinct Al-MMC coatings on a magnesium (AZ31) substrate. These coatings consisted of pure aluminum, a composition containing 4 vol% B4C, a composition with 4 vol% BNNTs, and a composition with 2 vol% B4C and 2 vol% BNNTs. Successful dispersion of nanoparticles within the aluminum matrix was achieved. The hardness of the coatings exhibited significant improvements compared to the pure aluminum coating. Specifically, the Al-BNNT coating showed a hardness increase of 14.1%, the Al-B4C-BNNT coating displayed a hardness increase of 20.8%, and the Al-B4C coating demonstrated the highest increase at 33.3% over the pure aluminum coating. Furthermore, the Al-B4C coating exhibited remarkable reductions in wear volume loss and wear track depth, amounting to eight and two orders of magnitude, respectively. Adhesion testing revealed that the Al-B4C-BNNT coating failed cohesively, while the pure aluminum coating failed adhesively at approximately the same force. The Al-B4C coating experienced a combination of the two failure modes at a 31.2% increase in force compared to the pure aluminum coating. Tensile testing stress vs. strain curves indicated that the load was partially supported by the cold spray coating until the coating ruptured.
{"title":"Reinforcing Cold Sprayed Al Coatings with Boron Nitride Nanotubes and Micro-Boron Carbide and their Effect on Surface Mechanical and Dry Sliding Behavior","authors":"A. Kulkarni, David Tauber, Troy Y. Ansell","doi":"10.1115/1.4063196","DOIUrl":"https://doi.org/10.1115/1.4063196","url":null,"abstract":"\u0000 This investigation explores the reinforcement effects of both boron nitride nanotubes (BNNTs) and micro-boron carbide (μB4C) on the tribological and mechanical properties of aluminum matrix composite (MMC) cold-sprayed coatings. The synthesis process involved high energy ball milling (HEBM) and cold spraying with helium to create four distinct Al-MMC coatings on a magnesium (AZ31) substrate. These coatings consisted of pure aluminum, a composition containing 4 vol% B4C, a composition with 4 vol% BNNTs, and a composition with 2 vol% B4C and 2 vol% BNNTs. Successful dispersion of nanoparticles within the aluminum matrix was achieved. The hardness of the coatings exhibited significant improvements compared to the pure aluminum coating. Specifically, the Al-BNNT coating showed a hardness increase of 14.1%, the Al-B4C-BNNT coating displayed a hardness increase of 20.8%, and the Al-B4C coating demonstrated the highest increase at 33.3% over the pure aluminum coating. Furthermore, the Al-B4C coating exhibited remarkable reductions in wear volume loss and wear track depth, amounting to eight and two orders of magnitude, respectively. Adhesion testing revealed that the Al-B4C-BNNT coating failed cohesively, while the pure aluminum coating failed adhesively at approximately the same force. The Al-B4C coating experienced a combination of the two failure modes at a 31.2% increase in force compared to the pure aluminum coating. Tensile testing stress vs. strain curves indicated that the load was partially supported by the cold spray coating until the coating ruptured.","PeriodicalId":17586,"journal":{"name":"Journal of Tribology-transactions of The Asme","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2023-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44386178","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 paper explores the performance of different commercial piston rings when matched with a boron-phosphorus (BP) alloy cast iron cylinder liner, specifically in high-power density diesel engines. The focus is on the friction, wear, and scuffing characteristics. An interrupted wear test was conducted under lean oil conditions to study the scuffing behavior of plated Cr-diamonds coating (GDC) and diamond-like carbon coating (DLC). The findings reveal that DLC coatings exhibit superior tribological properties, displaying low friction coefficients and wear loss at temperatures of 150 °C and 240 °C. In contrast, GDC coatings demonstrate relatively poor performance. Additionally, the DLC coating demonstrates excellent scuffing resistance, as no material transfer was observed for up to 77 minutes, even without lubrication. The interrupted scuffing test reveals that the scuffing process undergoes a stable wear stage, followed by a sudden drop and subsequent increase in friction force, ultimately resulting in scuffing when the BP cylinder is paired with GDC. On the other hand, although the frictional force of DLC initially increases after a brief decline, no significant adhesive wear is observed. This can be attributed to the formation of a tribo-chemical layer of carbides, which effectively prevents scuffing. In comparison to traditional methods of post-wear morphology and analysis, our proposed interrupted scuffing tests offer enhanced capabilities for evaluating the wear condition of friction pairs at various time intervals during the oil depletion process. This novel approach introduces a new paradigm for investigating wear patterns in different friction pairs.
{"title":"Tribological properties of several surface modified piston rings under extreme conditions","authors":"Yanrong Wang, Zongsheng Sun, Ruoxuan Huang, Zhiqiang Zhao, Weizheng Zhang","doi":"10.1115/1.4063187","DOIUrl":"https://doi.org/10.1115/1.4063187","url":null,"abstract":"\u0000 This paper explores the performance of different commercial piston rings when matched with a boron-phosphorus (BP) alloy cast iron cylinder liner, specifically in high-power density diesel engines. The focus is on the friction, wear, and scuffing characteristics. An interrupted wear test was conducted under lean oil conditions to study the scuffing behavior of plated Cr-diamonds coating (GDC) and diamond-like carbon coating (DLC). The findings reveal that DLC coatings exhibit superior tribological properties, displaying low friction coefficients and wear loss at temperatures of 150 °C and 240 °C. In contrast, GDC coatings demonstrate relatively poor performance. Additionally, the DLC coating demonstrates excellent scuffing resistance, as no material transfer was observed for up to 77 minutes, even without lubrication. The interrupted scuffing test reveals that the scuffing process undergoes a stable wear stage, followed by a sudden drop and subsequent increase in friction force, ultimately resulting in scuffing when the BP cylinder is paired with GDC. On the other hand, although the frictional force of DLC initially increases after a brief decline, no significant adhesive wear is observed. This can be attributed to the formation of a tribo-chemical layer of carbides, which effectively prevents scuffing. In comparison to traditional methods of post-wear morphology and analysis, our proposed interrupted scuffing tests offer enhanced capabilities for evaluating the wear condition of friction pairs at various time intervals during the oil depletion process. This novel approach introduces a new paradigm for investigating wear patterns in different friction pairs.","PeriodicalId":17586,"journal":{"name":"Journal of Tribology-transactions of The Asme","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2023-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49292675","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 past years, machining processes have been required when fabricating the complex Inconel 718 parts, and these processes cause undesired tensile residual stresses. Inconel 718 also exhibits extreme work hardening throughout the machining process. To avoid these issues, recently, Inconel 718 parts with high geometric complexity and dimensional accuracy, the laser powder bed fusion (LPBF) process, which belongs to additive manufacturing, has been extensively used. These Inconel 718 parts with LPBF processing are frequently utilized in various industries, including aerospace, automotive, pharmaceutical, and food processing, because of their high strength, biocompatibility, and corrosion resistance. Wear resistance is essential in addition to these properties for designing and crushing applications. In this paper, tribological tests were conducted on the LBPF-processed Inconel 718 parts and compared to casted Inconel 718 parts against the four types of counter bodies, namely boron carbide, silicon carbide, tungsten carbide, and titanium carbide. The studies were carried out for 30 min with a constant load of 5 N, frequency of 10 Hz, and stroke length of 1 mm. In comparison to casted samples, LBPF-processed samples showed low COF values. The highest COF was observed on the cast Inconel 718 against the tungsten carbide counter body. The wear mechanisms were studied using SEM.
{"title":"Experimental tribological study on additive manufactured Inconel 718 features against the hard carbide counter bodies","authors":"Mahaboob Basha M, M. R. Sankar","doi":"10.1115/1.4063192","DOIUrl":"https://doi.org/10.1115/1.4063192","url":null,"abstract":"\u0000 In past years, machining processes have been required when fabricating the complex Inconel 718 parts, and these processes cause undesired tensile residual stresses. Inconel 718 also exhibits extreme work hardening throughout the machining process. To avoid these issues, recently, Inconel 718 parts with high geometric complexity and dimensional accuracy, the laser powder bed fusion (LPBF) process, which belongs to additive manufacturing, has been extensively used. These Inconel 718 parts with LPBF processing are frequently utilized in various industries, including aerospace, automotive, pharmaceutical, and food processing, because of their high strength, biocompatibility, and corrosion resistance. Wear resistance is essential in addition to these properties for designing and crushing applications. In this paper, tribological tests were conducted on the LBPF-processed Inconel 718 parts and compared to casted Inconel 718 parts against the four types of counter bodies, namely boron carbide, silicon carbide, tungsten carbide, and titanium carbide. The studies were carried out for 30 min with a constant load of 5 N, frequency of 10 Hz, and stroke length of 1 mm. In comparison to casted samples, LBPF-processed samples showed low COF values. The highest COF was observed on the cast Inconel 718 against the tungsten carbide counter body. The wear mechanisms were studied using SEM.","PeriodicalId":17586,"journal":{"name":"Journal of Tribology-transactions of The Asme","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2023-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47650130","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 heat-treated nanoparticle MSHH was obtained based on the synthesis of lamellar nanoparticle MSH and analysis of thermal stability, and the morphology, phase composition, chemical groups of nanoparticles were subsequently characterized. The heat treatment process induces partial dehydroxylation of MSHH, while preserving the layered structure. Compared with MSH, the tribological performances of MSHH as lubricant additive have been greatly improved. The mechanical properties of MSH and MSHH are analyzed by calculation of elastic constants using density functional theory (DFT). The interactions among dispersant oleic acid (OA), nanoparticles (MSH and MSHH) and Fe tribopairs were investigated by simulations of classical molecular dynamics (CMD) from the views of adsorption energy and confined shear. The tribological mechanism of MSHH as lubricant additive is proposed based on the decreased shear strength and weakened agglomeration.
{"title":"Effect of dehydroxylation on tribological performances of synthetic magnesium silicate hydroxide as lubricant additive","authors":"Hao Zhang, Chenhui Zhang","doi":"10.1115/1.4063195","DOIUrl":"https://doi.org/10.1115/1.4063195","url":null,"abstract":"\u0000 The heat-treated nanoparticle MSHH was obtained based on the synthesis of lamellar nanoparticle MSH and analysis of thermal stability, and the morphology, phase composition, chemical groups of nanoparticles were subsequently characterized. The heat treatment process induces partial dehydroxylation of MSHH, while preserving the layered structure. Compared with MSH, the tribological performances of MSHH as lubricant additive have been greatly improved. The mechanical properties of MSH and MSHH are analyzed by calculation of elastic constants using density functional theory (DFT). The interactions among dispersant oleic acid (OA), nanoparticles (MSH and MSHH) and Fe tribopairs were investigated by simulations of classical molecular dynamics (CMD) from the views of adsorption energy and confined shear. The tribological mechanism of MSHH as lubricant additive is proposed based on the decreased shear strength and weakened agglomeration.","PeriodicalId":17586,"journal":{"name":"Journal of Tribology-transactions of The Asme","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2023-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47393201","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}
T. Guo, Hao-xian Shi, Ruguo Ji, Bo Li, Chenhang Wang
In practice, it is difficult to avoid the axis angle deviation when some regular surfaces are in micro-sliding, such as gears, machined surfaces, etc. In order to better investigate the micro-motion contact characteristics, a crossed paraboloidal contact model under frictional condition is proposed to simulate both tangential displacement-controlled fretting and the evolution of the energy dissipation in a load cycle. By deriving the theoretical of the normal and tangential contact course of the model, the load-displacement curves during initial loading, unloading and reloading stage are presented. On this basis, the hysteresis curve is then obtained by integrating the closed area surrounded by load-displacement during unloading and reloading, which also means that the empirical formulation for micro-slip in a load cycle is constructed. This study also reveals the plastic yield phenomenon under pure normal loading and plastic shakedown behavior caused by cyclic reciprocating displacement loads. In addition, the research on the junction growth, the evolution of tangential load and hysteresis curve with different COFs under multiple-cycle load is also carried out. The implications of involved parameters, such as friction coefficient, axis intersection angle, normal load and so on, are discussed with respect to hysteresis curve shape and energy dissipation. The difference about hysteresis and energy dissipation curves between the paraboloidal contact model and other classic contact models is then presented. It is discovered by comparison with other models that the paraboloidal contact model presents a relatively high energy dissipation in a load cycle.
{"title":"Analysis of Displacement-Controlled Fretting Between Crossed Parabolic Cylinders in Elasto-plastic Contacts","authors":"T. Guo, Hao-xian Shi, Ruguo Ji, Bo Li, Chenhang Wang","doi":"10.1115/1.4063198","DOIUrl":"https://doi.org/10.1115/1.4063198","url":null,"abstract":"\u0000 In practice, it is difficult to avoid the axis angle deviation when some regular surfaces are in micro-sliding, such as gears, machined surfaces, etc. In order to better investigate the micro-motion contact characteristics, a crossed paraboloidal contact model under frictional condition is proposed to simulate both tangential displacement-controlled fretting and the evolution of the energy dissipation in a load cycle. By deriving the theoretical of the normal and tangential contact course of the model, the load-displacement curves during initial loading, unloading and reloading stage are presented. On this basis, the hysteresis curve is then obtained by integrating the closed area surrounded by load-displacement during unloading and reloading, which also means that the empirical formulation for micro-slip in a load cycle is constructed. This study also reveals the plastic yield phenomenon under pure normal loading and plastic shakedown behavior caused by cyclic reciprocating displacement loads. In addition, the research on the junction growth, the evolution of tangential load and hysteresis curve with different COFs under multiple-cycle load is also carried out. The implications of involved parameters, such as friction coefficient, axis intersection angle, normal load and so on, are discussed with respect to hysteresis curve shape and energy dissipation. The difference about hysteresis and energy dissipation curves between the paraboloidal contact model and other classic contact models is then presented. It is discovered by comparison with other models that the paraboloidal contact model presents a relatively high energy dissipation in a load cycle.","PeriodicalId":17586,"journal":{"name":"Journal of Tribology-transactions of The Asme","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2023-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42809616","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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