Pub Date : 2023-10-29DOI: 10.3390/lubricants11110461
Ronit Shah, Naveen Venkatesh Sridharan, Tapan K. Mahanta, Amarnath Muniyappa, Sugumaran Vaithiyanathan, Sangharatna M. Ramteke, Max Marian
This technical note focuses on the application of deep learning techniques in the area of lubrication technology and tribology. This paper introduces a novel approach by employing deep learning methodologies to extract features from scanning electron microscopy (SEM) images, which depict wear particles obtained through the extraction and filtration of lubricating oil from a 4-stroke petrol internal combustion engine following varied travel distances. Specifically, this work postulates that the amalgamation of ensemble deep learning, involving the combination of multiple deep learning models, leads to greater accuracy compared to individually trained techniques. To substantiate this hypothesis, a fusion of deep learning methods is implemented, featuring deep convolutional neural network (CNN) architectures including Xception, Inception V3, and MobileNet V2. Through individualized training of each model, accuracies reached 85.93% for MobileNet V2 and 93.75% for Inception V3 and Xception. The major finding of this study is the hybrid ensemble deep learning model, which displayed a superior accuracy of 98.75%. This outcome not only surpasses the performance of the singularly trained models, but also substantiates the viability of the proposed hypothesis. This technical note highlights the effectiveness of utilizing ensemble deep learning methods for extracting wear particle features from SEM images. The demonstrated achievements of the hybrid model strongly support its adoption to improve predictive analytics and gain insights into intricate wear mechanisms across various engineering applications.
{"title":"Ensemble Deep Learning for Wear Particle Image Analysis","authors":"Ronit Shah, Naveen Venkatesh Sridharan, Tapan K. Mahanta, Amarnath Muniyappa, Sugumaran Vaithiyanathan, Sangharatna M. Ramteke, Max Marian","doi":"10.3390/lubricants11110461","DOIUrl":"https://doi.org/10.3390/lubricants11110461","url":null,"abstract":"This technical note focuses on the application of deep learning techniques in the area of lubrication technology and tribology. This paper introduces a novel approach by employing deep learning methodologies to extract features from scanning electron microscopy (SEM) images, which depict wear particles obtained through the extraction and filtration of lubricating oil from a 4-stroke petrol internal combustion engine following varied travel distances. Specifically, this work postulates that the amalgamation of ensemble deep learning, involving the combination of multiple deep learning models, leads to greater accuracy compared to individually trained techniques. To substantiate this hypothesis, a fusion of deep learning methods is implemented, featuring deep convolutional neural network (CNN) architectures including Xception, Inception V3, and MobileNet V2. Through individualized training of each model, accuracies reached 85.93% for MobileNet V2 and 93.75% for Inception V3 and Xception. The major finding of this study is the hybrid ensemble deep learning model, which displayed a superior accuracy of 98.75%. This outcome not only surpasses the performance of the singularly trained models, but also substantiates the viability of the proposed hypothesis. This technical note highlights the effectiveness of utilizing ensemble deep learning methods for extracting wear particle features from SEM images. The demonstrated achievements of the hybrid model strongly support its adoption to improve predictive analytics and gain insights into intricate wear mechanisms across various engineering applications.","PeriodicalId":18135,"journal":{"name":"Lubricants","volume":"10 5","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136158126","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}
Pub Date : 2023-10-28DOI: 10.3390/lubricants11110460
Tomasz Dubiel, Rafał Grzejda
The aim of this article is to investigate the effect of atmospheric conditions on the tightening behaviour of HV bolts in structural bolt sets. The article describes the results of experimental tests carried out for bolt sets of a selected type. The parts of the joined sets were stored according to the specified six different conditions for four weeks before assembly. Paper, cardboard boxes and anticorrosion foils were used as protection against atmospheric conditions. The behaviour of unassembled and assembled bolt sets was also taken into account. The variation in the friction coefficient depending on the clamping force and storage conditions of the bolt sets was demonstrated. This applies both to the contact between the joining elements on the threaded surfaces and to the area between the bolt head and the bearing surface of the nut and washer.
{"title":"Effect of Atmospheric Conditions on the Tightening Behaviour of HV Galvanised Bolts in Structural Bolt Sets","authors":"Tomasz Dubiel, Rafał Grzejda","doi":"10.3390/lubricants11110460","DOIUrl":"https://doi.org/10.3390/lubricants11110460","url":null,"abstract":"The aim of this article is to investigate the effect of atmospheric conditions on the tightening behaviour of HV bolts in structural bolt sets. The article describes the results of experimental tests carried out for bolt sets of a selected type. The parts of the joined sets were stored according to the specified six different conditions for four weeks before assembly. Paper, cardboard boxes and anticorrosion foils were used as protection against atmospheric conditions. The behaviour of unassembled and assembled bolt sets was also taken into account. The variation in the friction coefficient depending on the clamping force and storage conditions of the bolt sets was demonstrated. This applies both to the contact between the joining elements on the threaded surfaces and to the area between the bolt head and the bearing surface of the nut and washer.","PeriodicalId":18135,"journal":{"name":"Lubricants","volume":"194 2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136231724","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}
Pub Date : 2023-10-27DOI: 10.3390/lubricants11110459
Johannes Wirkner, Mirjam Baese, Astrid Lebel, Hermann Pflaum, Katharina Voelkel, Lukas Pointner-Gabriel, Charlotte Besser, Thomas Schneider, Karsten Stahl
The driving comfort and safety of the automotive powertrain are significantly related to the performance, lifetime, and functionality of the lubricant. The presented study focuses on investigating the performance loss of the lubricant due to water contamination resulting from environmental influences and iron particles originating from the wear of different machine elements. The main purpose is to determine critical factors that contribute to the degradation of the lubricant, and increase the tendency to NVH behavior, leading to adverse comfort losses to the respective user. Therefore, this performance loss is evaluated by test rig-based analysis of the friction behavior of wet clutches. Due to physical adsorption, a significant impact of water and iron contamination on the degradation of the lubricant is found, while the influence of the energy input is secondary.
{"title":"Influence of Water Contamination, Iron Particles, and Energy Input on the NVH Behavior of Wet Clutches","authors":"Johannes Wirkner, Mirjam Baese, Astrid Lebel, Hermann Pflaum, Katharina Voelkel, Lukas Pointner-Gabriel, Charlotte Besser, Thomas Schneider, Karsten Stahl","doi":"10.3390/lubricants11110459","DOIUrl":"https://doi.org/10.3390/lubricants11110459","url":null,"abstract":"The driving comfort and safety of the automotive powertrain are significantly related to the performance, lifetime, and functionality of the lubricant. The presented study focuses on investigating the performance loss of the lubricant due to water contamination resulting from environmental influences and iron particles originating from the wear of different machine elements. The main purpose is to determine critical factors that contribute to the degradation of the lubricant, and increase the tendency to NVH behavior, leading to adverse comfort losses to the respective user. Therefore, this performance loss is evaluated by test rig-based analysis of the friction behavior of wet clutches. Due to physical adsorption, a significant impact of water and iron contamination on the degradation of the lubricant is found, while the influence of the energy input is secondary.","PeriodicalId":18135,"journal":{"name":"Lubricants","volume":"162 12","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136234331","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}
Self-supporting run-flat tires (SSRFTs) achieve good zero-pressure driving ability by reinforcing the sidewalls, and the structural shape of sidewall insert rubber (SIR) is critical in influencing the mechanical characteristics of SSRFTs. In this paper, an SSRFT contour model is established by combining the radial tire contour theory and the design elements of SIR. The influence of two design parameters (maximum width L and maximum thickness H) of SIR on the tire stiffness characteristics and the contact characteristics is analyzed in depth, and the accuracy of the model is verified by the tire mechanics bench test. The results show that the radial stiffness of SSRFTs is positively correlated with two design parameters; an increase in L affects the stress concentration at the end of SIR, while a change in H has a more drastic effect on the stress distribution of SIR, leading to a large change in both the location of the deformation of SIR and the maximum equivalent stress; under rated pressure conditions, when L is less than 100 mm, the overlap between SIR and the tread decreases, which in turn makes the contact characteristics of SSRFTs closer to that of a normal tire, and obtains better comfort and abrasion resistance; under zero-pressure conditions, the maximum contact stress of the tread is the smallest when the H is 8 mm, but when H is less than 6 mm, the contact characteristics appear to deteriorate uniformly, and the maximum contact stress continues to rise. The results of the research provide a reference value for the selection of the design parameters for SIR and the optimization of the dynamic performance of SSRFTs.
{"title":"Study on the Effect of Different Design Parameters of Sidewall Insert Rubber on the Mechanical Characteristics of Self-Supporting Run-Flat Tires","authors":"Tian Lv, Liguo Zang, Cheng Xue, Yaowei Li, Yulin Mao, Xingyu Wang","doi":"10.3390/lubricants11110458","DOIUrl":"https://doi.org/10.3390/lubricants11110458","url":null,"abstract":"Self-supporting run-flat tires (SSRFTs) achieve good zero-pressure driving ability by reinforcing the sidewalls, and the structural shape of sidewall insert rubber (SIR) is critical in influencing the mechanical characteristics of SSRFTs. In this paper, an SSRFT contour model is established by combining the radial tire contour theory and the design elements of SIR. The influence of two design parameters (maximum width L and maximum thickness H) of SIR on the tire stiffness characteristics and the contact characteristics is analyzed in depth, and the accuracy of the model is verified by the tire mechanics bench test. The results show that the radial stiffness of SSRFTs is positively correlated with two design parameters; an increase in L affects the stress concentration at the end of SIR, while a change in H has a more drastic effect on the stress distribution of SIR, leading to a large change in both the location of the deformation of SIR and the maximum equivalent stress; under rated pressure conditions, when L is less than 100 mm, the overlap between SIR and the tread decreases, which in turn makes the contact characteristics of SSRFTs closer to that of a normal tire, and obtains better comfort and abrasion resistance; under zero-pressure conditions, the maximum contact stress of the tread is the smallest when the H is 8 mm, but when H is less than 6 mm, the contact characteristics appear to deteriorate uniformly, and the maximum contact stress continues to rise. The results of the research provide a reference value for the selection of the design parameters for SIR and the optimization of the dynamic performance of SSRFTs.","PeriodicalId":18135,"journal":{"name":"Lubricants","volume":"49 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136382223","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}
Pub Date : 2023-10-25DOI: 10.3390/lubricants11110457
Tareq M. A. Al-Quraan, Fadi Alfaqs, Jamil Haddad, Viktor Vojtov, Anton Voitov, Andrey Kravtsov, Oleksandr Miroshnyk, Andrii Kondratiev
Based on the analysis of standards for the testing of lubricants, both liquid and plastic, on a four-ball tribometer, and the analysis of the parameters by which lubricants are evaluated, this paper proposes a methodology and an integral parameter for the estimation of tribological properties. The methodological approach proposed in this paper allows for the integration of a variety of parameters provided in the standards for the testing of lubricants into one indicator. Herein, we show that the developed technique is based on the energy approach and takes into account the specific wear work of the test material (steel balls) in the lubricating medium to be investigated. The results of laboratory tests of a wide range of lubricants are presented: hydraulic fluids, motor and transmission oils of various purposes and classifications. It is shown that the magnitude of the integral parameter can be used to assess the effectiveness of anti-wear and anti-scuff additives in base lubricants, as well as the ranges of their applications. This allows for differentiation and quantitative evaluation of the effectiveness of such additives. The obtained results allow us to state that all tests according to the developed method are reproducible and homogeneous, which is confirmed using the Cochran criterion. The coefficient of variation during testing does not exceed 18%. We show that the presented methodology and the integral parameter can be used in the first stage of the laboratory selection tests of new lubricants and additives of various origins, reducing the costs of their development and implementation.
{"title":"A Methodological Approach to Assessing the Tribological Properties of Lubricants Using a Four-Ball Tribometer","authors":"Tareq M. A. Al-Quraan, Fadi Alfaqs, Jamil Haddad, Viktor Vojtov, Anton Voitov, Andrey Kravtsov, Oleksandr Miroshnyk, Andrii Kondratiev","doi":"10.3390/lubricants11110457","DOIUrl":"https://doi.org/10.3390/lubricants11110457","url":null,"abstract":"Based on the analysis of standards for the testing of lubricants, both liquid and plastic, on a four-ball tribometer, and the analysis of the parameters by which lubricants are evaluated, this paper proposes a methodology and an integral parameter for the estimation of tribological properties. The methodological approach proposed in this paper allows for the integration of a variety of parameters provided in the standards for the testing of lubricants into one indicator. Herein, we show that the developed technique is based on the energy approach and takes into account the specific wear work of the test material (steel balls) in the lubricating medium to be investigated. The results of laboratory tests of a wide range of lubricants are presented: hydraulic fluids, motor and transmission oils of various purposes and classifications. It is shown that the magnitude of the integral parameter can be used to assess the effectiveness of anti-wear and anti-scuff additives in base lubricants, as well as the ranges of their applications. This allows for differentiation and quantitative evaluation of the effectiveness of such additives. The obtained results allow us to state that all tests according to the developed method are reproducible and homogeneous, which is confirmed using the Cochran criterion. The coefficient of variation during testing does not exceed 18%. We show that the presented methodology and the integral parameter can be used in the first stage of the laboratory selection tests of new lubricants and additives of various origins, reducing the costs of their development and implementation.","PeriodicalId":18135,"journal":{"name":"Lubricants","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135216818","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}
Friction involved in metal-forming processes typically leads to the wear of tool and die surfaces, and in turn shortens the tool’s service life. A thriving need for reducing surface friction requires the tool surface to be modified. This paper presents the surface modification of SKH51 tool steel, on which the hexagonal array of micro-dimples is fabricated by a nanosecond pulse laser. Using the average laser power of 25 W can create decent dimples for trapping lubricant and enabling hydraulic pressure at the surfaces in contact. The effect of dimple density and sliding speed on the coefficient of friction was examined in this study through the pin-on-disc test, in which a stainless steel pin was applied against the tool steel disc with a constant load. The laser-textured tool steel surface with a dimple density of 35% had a friction coefficient of 0.087, which was lower than that of the untextured surface by 12.6% when using a sliding speed of 15 cm/s. In addition to friction reduction, there was no substantial wear found on the laser-textured surface compared to the untextured sample. The findings of this study can be a processing guideline and benefit the treatment of tool and die surfaces for friction and wear reduction in metal-forming and related processes.
{"title":"Laser-Fabricated Micro-Dimples for Improving Frictional Property of SKH51 Tool Steel Surfaces","authors":"Chansovannkumpheak Phun, Witthaya Daodon, Kamthon Septham, Peerapong Kumkhuntod, Hao Zhu, Viboon Saetang","doi":"10.3390/lubricants11110456","DOIUrl":"https://doi.org/10.3390/lubricants11110456","url":null,"abstract":"Friction involved in metal-forming processes typically leads to the wear of tool and die surfaces, and in turn shortens the tool’s service life. A thriving need for reducing surface friction requires the tool surface to be modified. This paper presents the surface modification of SKH51 tool steel, on which the hexagonal array of micro-dimples is fabricated by a nanosecond pulse laser. Using the average laser power of 25 W can create decent dimples for trapping lubricant and enabling hydraulic pressure at the surfaces in contact. The effect of dimple density and sliding speed on the coefficient of friction was examined in this study through the pin-on-disc test, in which a stainless steel pin was applied against the tool steel disc with a constant load. The laser-textured tool steel surface with a dimple density of 35% had a friction coefficient of 0.087, which was lower than that of the untextured surface by 12.6% when using a sliding speed of 15 cm/s. In addition to friction reduction, there was no substantial wear found on the laser-textured surface compared to the untextured sample. The findings of this study can be a processing guideline and benefit the treatment of tool and die surfaces for friction and wear reduction in metal-forming and related processes.","PeriodicalId":18135,"journal":{"name":"Lubricants","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135274054","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}
Pub Date : 2023-10-23DOI: 10.3390/lubricants11100455
Omid Safdarzadeh, Resat Capan, Michel Werner, Andreas Binder, Oliver Koch
The effect of variable DC bearing current amplitude, bearing current polarity, mechanical force, rotation speed, bearing temperature, and number of the balls on the fluting in an axial ball bearing type 51208 is investigated under DC currents. The results are obtained from two different test setups with two different lubricants (mineral-oil-based grease and polyglycol oil). The speed varies between 100 rpm and 2000 rpm, the axial bearing force between 200 N and 2400 N, the DC current amplitude between 0.5 A and 20 A, the bearing temperature between 29 °C and 80 °C, the number of steel balls per bearing between 3 and 15, and the test duration between 6 h and 168 h. The results show that with a higher bearing current density and/or a higher bearing speed, a lower bearing force and/or a lower bearing temperature, a bigger number of roller elements, but also at a negative polarity of a DC electric bearing current, the occurring of fluting is more probable and occurs at an earlier stage of operation.
{"title":"Influencing Factors on the Fluting in an Axial Ball Bearing at DC Bearing Currents","authors":"Omid Safdarzadeh, Resat Capan, Michel Werner, Andreas Binder, Oliver Koch","doi":"10.3390/lubricants11100455","DOIUrl":"https://doi.org/10.3390/lubricants11100455","url":null,"abstract":"The effect of variable DC bearing current amplitude, bearing current polarity, mechanical force, rotation speed, bearing temperature, and number of the balls on the fluting in an axial ball bearing type 51208 is investigated under DC currents. The results are obtained from two different test setups with two different lubricants (mineral-oil-based grease and polyglycol oil). The speed varies between 100 rpm and 2000 rpm, the axial bearing force between 200 N and 2400 N, the DC current amplitude between 0.5 A and 20 A, the bearing temperature between 29 °C and 80 °C, the number of steel balls per bearing between 3 and 15, and the test duration between 6 h and 168 h. The results show that with a higher bearing current density and/or a higher bearing speed, a lower bearing force and/or a lower bearing temperature, a bigger number of roller elements, but also at a negative polarity of a DC electric bearing current, the occurring of fluting is more probable and occurs at an earlier stage of operation.","PeriodicalId":18135,"journal":{"name":"Lubricants","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135366310","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}
Pub Date : 2023-10-22DOI: 10.3390/lubricants11100454
Rifat Yakut
In this study, grey cast iron (GG25) was produced via reinforcement with carbon titanium nitride (TiNC) in different amounts (0%, 0.153%, 0.204% and 0.255%). Samples were made from this material according to the standards for hardness, compression and wear, and then experiments were conducted. The test conditions applied for the TiNC-reinforced samples were similarly applied to unreinforced samples. The TiNC-reinforced and unreinforced samples were compared regarding their compression, hardness, and wear properties. The results of the hardness tests showed the highest average hardness value of 215 HB for sample A (0% TiNC). For TiNC-reinforced specimens, the hardness values of the reinforced specimens increased with increasing reinforcement. Sample B (0.153% TiNC) had an average hardness value of 193 HB. For sample C (0.204% TiNC), an average hardness value of 200 HB was measured. For sample D (0.255% TiNC), an average hardness value of 204 HB was determined. Sample A’s highest compression strength value was 780 MPA (0% TiNC). Similar to the hardness test values, the compression strength of the reinforced samples increased with the increasing reinforcement rate. The compression test value was found to be 747 MPa for sample B (0.153% TiNC), 765 MPa for sample C (0.204% TiNC) and 778 MPa for sample D (0.255% TiNC). Wear tests were performed on all samples to examine changes in the wear volume loss, wear rate and friction coefficients. Scanning electron microscopy (SEM) was used to determine the wear mechanisms on the worn surfaces of the samples. When examining the wear condition of the samples with the same hardness value as a function of increasing load values, increases in the wear volume loss values were observed as the load value increased.
{"title":"Investigation of Mechanical Properties of Grey Cast Irons Reinforced with Carbon Titanium Nitride (TiNC)","authors":"Rifat Yakut","doi":"10.3390/lubricants11100454","DOIUrl":"https://doi.org/10.3390/lubricants11100454","url":null,"abstract":"In this study, grey cast iron (GG25) was produced via reinforcement with carbon titanium nitride (TiNC) in different amounts (0%, 0.153%, 0.204% and 0.255%). Samples were made from this material according to the standards for hardness, compression and wear, and then experiments were conducted. The test conditions applied for the TiNC-reinforced samples were similarly applied to unreinforced samples. The TiNC-reinforced and unreinforced samples were compared regarding their compression, hardness, and wear properties. The results of the hardness tests showed the highest average hardness value of 215 HB for sample A (0% TiNC). For TiNC-reinforced specimens, the hardness values of the reinforced specimens increased with increasing reinforcement. Sample B (0.153% TiNC) had an average hardness value of 193 HB. For sample C (0.204% TiNC), an average hardness value of 200 HB was measured. For sample D (0.255% TiNC), an average hardness value of 204 HB was determined. Sample A’s highest compression strength value was 780 MPA (0% TiNC). Similar to the hardness test values, the compression strength of the reinforced samples increased with the increasing reinforcement rate. The compression test value was found to be 747 MPa for sample B (0.153% TiNC), 765 MPa for sample C (0.204% TiNC) and 778 MPa for sample D (0.255% TiNC). Wear tests were performed on all samples to examine changes in the wear volume loss, wear rate and friction coefficients. Scanning electron microscopy (SEM) was used to determine the wear mechanisms on the worn surfaces of the samples. When examining the wear condition of the samples with the same hardness value as a function of increasing load values, increases in the wear volume loss values were observed as the load value increased.","PeriodicalId":18135,"journal":{"name":"Lubricants","volume":"25 3","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135461543","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}
Pub Date : 2023-10-20DOI: 10.3390/lubricants11100453
Bin Hu, Xiaodong Yang, Anping Hou, Rui Wang, Zhiyong Wu, Qifeng Ni, Zhong Li
This study focuses on thick top foil bearings (TTFBs), which can prevent top foil from sagging and significantly reduce the load capacity of gas foil bearings (GFBs). However, the limited research on the dynamic responses of TTFB-rotor systems has hindered their wide application of TTFBs with high load capacity. To address this, an integrated nonlinear dynamic model is developed to analyze the linear dynamic responses of a rigid rotor supported on TTFBs. The model incorporates time domain orbit simulation, considering unsteady Reynolds equations, foil deformation equations, thick top foil motion equations, and rotor motion equations. A symmetrical test rig is used to validate the model, and three types of TTFBs with different bump foil stiffness are tested, with experimental results aligning with the model predictions. This study also investigates the effects of nominal clearance, static load, and unbalance on TTFB-rotor systems. The results indicate that unbalance has minimal impact on subsynchronous vibrations. However, larger bump foil stiffness, increased normal clearance, and higher static load contribute to improved stability and higher maximum stable speed of the TTFB-rotor system. Moreover, other relevant parameters reducing the bearing attitude angle can further enhance the system’s stability.
{"title":"Nonlinear Dynamic Responses of Rigid Rotor Supported by Thick Top Foil Bearings","authors":"Bin Hu, Xiaodong Yang, Anping Hou, Rui Wang, Zhiyong Wu, Qifeng Ni, Zhong Li","doi":"10.3390/lubricants11100453","DOIUrl":"https://doi.org/10.3390/lubricants11100453","url":null,"abstract":"This study focuses on thick top foil bearings (TTFBs), which can prevent top foil from sagging and significantly reduce the load capacity of gas foil bearings (GFBs). However, the limited research on the dynamic responses of TTFB-rotor systems has hindered their wide application of TTFBs with high load capacity. To address this, an integrated nonlinear dynamic model is developed to analyze the linear dynamic responses of a rigid rotor supported on TTFBs. The model incorporates time domain orbit simulation, considering unsteady Reynolds equations, foil deformation equations, thick top foil motion equations, and rotor motion equations. A symmetrical test rig is used to validate the model, and three types of TTFBs with different bump foil stiffness are tested, with experimental results aligning with the model predictions. This study also investigates the effects of nominal clearance, static load, and unbalance on TTFB-rotor systems. The results indicate that unbalance has minimal impact on subsynchronous vibrations. However, larger bump foil stiffness, increased normal clearance, and higher static load contribute to improved stability and higher maximum stable speed of the TTFB-rotor system. Moreover, other relevant parameters reducing the bearing attitude angle can further enhance the system’s stability.","PeriodicalId":18135,"journal":{"name":"Lubricants","volume":"73 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135617073","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 growing awareness of reduced friction losses and new demands for electrical powertrains demand improved lubricants. Due to their unique properties, such as high thermal and electrical conductivity, graphene and its derivatives have been investigated for tribological applications, especially as lubricant additives. In this work, we investigated three commercially available graphene variants, one comprising a few layers and the other two comprising nanoplates, after functionalization as additives to lithium soap grease. The grease temperature dropping point increased by approximately 6 °C. Additionally, during the reciprocating friction test, friction increased with the test duration for the baseline grease, whereas it decreased for the ones containing graphene-based additives. On the test end, friction was reduced by 8% compared to the baseline grease. On a four-ball tribometer, the wear scar was reduced from 10 to 18% compared to the baseline grease. In general, no significant difference was seen between the three graphene-based variants. The promising results found with graphene nanoplates, a less expensive material than a few graphene layers, creates opportunities for a cost-competitive additive to commercial greases.
{"title":"Use of Functionalized Graphene-Based Materials on Grease","authors":"Eduardo Tomanik, Paulo Berto, Wania Christinelli, Gabriela Papoulias, Xavier Raby, Valdirene Peressinotto","doi":"10.3390/lubricants11100452","DOIUrl":"https://doi.org/10.3390/lubricants11100452","url":null,"abstract":"The growing awareness of reduced friction losses and new demands for electrical powertrains demand improved lubricants. Due to their unique properties, such as high thermal and electrical conductivity, graphene and its derivatives have been investigated for tribological applications, especially as lubricant additives. In this work, we investigated three commercially available graphene variants, one comprising a few layers and the other two comprising nanoplates, after functionalization as additives to lithium soap grease. The grease temperature dropping point increased by approximately 6 °C. Additionally, during the reciprocating friction test, friction increased with the test duration for the baseline grease, whereas it decreased for the ones containing graphene-based additives. On the test end, friction was reduced by 8% compared to the baseline grease. On a four-ball tribometer, the wear scar was reduced from 10 to 18% compared to the baseline grease. In general, no significant difference was seen between the three graphene-based variants. The promising results found with graphene nanoplates, a less expensive material than a few graphene layers, creates opportunities for a cost-competitive additive to commercial greases.","PeriodicalId":18135,"journal":{"name":"Lubricants","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135616913","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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