Tribological Research Research Articles

Investigation of friction and wear characteristics between modular charge and aluminum alloy for feeding process in artillery systems

In modern artillery systems, frictional properties of modular charge significantly impact the operation of artillery feeding system. In this study, Tribology performance between modular charge and aluminum alloy were investigated under simulated environment of artillery. The result indicates that the COF initially increased and then decreases with the temperature dropped from 50 °C to −40 °C. Additionally, COF increased from 0.19 to 0.41 when relative velocity increased from 100 mm/s to 2000mm/s. SEM detection and chemical composition analysis demonstrated that the main wear forms are adhesive wear and abrasive wear. The tribofilm including aluminum titanium oxide and aluminum nitrides generated through tribochemical reaction, which are beneficial for boundary lubrication. This work provides theoretical reference for artillery tribology research.

Integrating Friction Noise for In-Situ Monitoring of Polymer Wear Performance: A Machine Learning Approach in Tribology

Abstract Friction and wear between mating surfaces significantly affect the efficiency and performance of mechanical systems. Traditional tribological research relies on post-observation methods, limiting the understanding of dynamic friction behavior. In contrast, in-situ monitoring provides real-time insights into evolving friction dynamics. This study employs machine learning to monitor polymer wear performance through friction noise. The predictive accuracy of various machine learning methods, including Extremely Randomized Trees, Gradient-Boosting Decision Trees, AdaBoost, LightGBM, Deep Forest, and Deep Neural Networks, is compared for wear type classification. Additionally, the LSBoost regression is selected as the optimal method for predicting polymer wear rates across various temperatures. The results underscore the potential of using friction noise and machine learning for real-time wear monitoring, offering valuable insights for tribological system maintenance and failure prediction.

Tribological Research of Resin Composites with the Fillers of Glass Powder and Micro-Bubbles.

This study investigates the tribological properties of resin composites reinforced with the fillers of glass powder and micro-bubbles. Resin composites were prepared with varying concentrations from 1% to 5% wt of fillers. Tribological tests were conducted using a block-on-ring scheme under dry friction conditions. The measurements of friction coefficient and wear values were performed under variable rotation speeds and loading conditions. The study showed that resin composites with 2-3% glass powder fillers and resin composites with 3-4% micro-bubbles exhibited optimal tribological properties. The resin glass powder modifications reduce the wear by 63% and resin micro-bubbles reduce wear by 32%. SEM analysis of the surfaces revealed surface imperfections and structural damage mechanisms, including abrasive and fatigue wear. The study concludes that specific filler concentrations improve the friction and wear resistance of resin composites, highlighting the importance of material preparation and surface quality in tribological performance. The increased wear resistance on both composites would hopefully expand the usage of additive manufactured composite, namely industrial moving components such as polymer gear, wheel, pulley, etc.

Mechanical and Tribological properties of the Lead-Free Composite-A review

In recent years, there has been a growing demand for materials that are both eco-friendly and cost-effective while maintaining high performance levels. Design engineers and researchers are increasingly turning to advanced materials as substitutes for traditional metals and alloys. Journal bearings, integral components of machinery and engines, play a crucial role in their operation, significantly impacting efficiency, operational costs, system longevity, and reliability. The pursuit of eco-friendly and high-performance materials has spurred notable progress in tribological research, particularly concerning journal bearings. This study offers a comprehensive examination of lead-free composite materials for journal bearings, delving into various types such as polymers, ceramics, and metallic alloys. It meticulously evaluates their mechanical and tribological properties, as well as their microstructural characteristics. The insights gleaned from this review are invaluable for engineers and researchers seeking to enhance the design and performance of journal bearings while aligning with environmental regulations and sustainability objectives.

Molecular Dynamics Simulation on Polymer Tribology: A Review

A profound comprehension of friction and wear mechanisms is essential for the design and development of high-performance polymeric materials for tribological application. However, it is difficult to deeply investigate the polymer friction process in situ at the micro/mesoscopic scale by traditional research methods. In recent years, molecular dynamics (MD) simulation, as an emerging research method, has attracted more and more attention in the field of polymer tribology due to its ability to show the physicochemical evolution between the contact interfaces at the atomic scale. Herein, we review the applications of MD in recent studies of polymer tribology and their research focuses (e.g., tribological properties, distribution and conformation of polymer chains, interfacial interaction, frictional heat, and tribochemical reactions) across three perspectives: all-atom MD, reactive MD, and coarse-grained MD. Additionally, we summarize the current challenges encountered by MD simulation in polymer tribology research and present recommendations accordingly, aiming to provide several insights for researchers in related fields.

Experimental and molecular dynamics simulation based investigation to understand tribological performance of graphene reinforced thermoplastic polyurethane (Gr/TPU) nanocomposites

Ongoing innovative research in tribology aims to develop high-performance polymer nanocomposite (PNC) materials that offer significant improvements in efficiency, reliability, and durability across various engineering systems. Selection of appropriate nanoreinforcements is crucial for maximizing the tribological behavior in PNCs. The primary objective is to investigate how various factors, such as graphene (Gr) loadings, processing techniques, normal loading, and sliding velocity influence the tribological behavior of thermoplastic polyurethane (TPU) and graphene reinforced thermoplastic polyurethane (Gr/TPU) nanocomposites using molecular dynamics (MD) simulation and experiments. Nanocomposite materials fabricated by ultrasonication methods, test specimens are prepared in appropriate dimensions as per ASTM (American Society for Testing and Materials) and DIN (Deutsches Institut für Normung) standard. MD simulations are conducted on the developed plate and rod models under different sliding velocity, pressing and stabbing depth conditions to understand fundamental insights into the friction and wear mechanisms of Gr/TPU nanocomposites at the atomic level. Morphological studies using scanning electron microscopy (SEM) micrographs indicate no case of Gr agglomeration up to 3 wt% Gr/TPU nanocomposite. Energy dispersive spectroscopy (EDS) analysis confirms presence of Carbon (c), Nitrogen (N) and Oxygen (O) in Gr/TPU nanocomposites. Finally the obtained results from MD simulation and experiments show a significant trend of similarity.

Investigation of contact behavior on a model of the dual-mobility artificial hip joint for Asians in different inner liner thicknesses.

The four components that make up the current dual-mobility artificial hip joint design are the femoral head, the inner liner, the outer liner as a metal cover to prevent wear, and the acetabular cup. The acetabular cup and the outer liner were constructed of 316L stainless steel. At the same time, the inner liner was made of ultra-high-molecular-weight polyethylene (UHMWPE). As this new dual-mobility artificial hip joint has not been researched extensively, more tribological research is needed to predict wear. The thickness of the inner liner is a significant component to consider when calculating the contact pressure. To make use of finite element analysis to gain a better understanding of the contact behavior in various inner liner thicknesses on a new model of a dual-mobility artificial hip joint, with the ultimate objective of determining the inner liner thickness that was most suitable for this particular type of dual-mobility artificial hip joint. In this study, the size of the femoral head was compared between two diameters (28 mm and 36 mm) and eight inner liner thicknesses ranging from 5 mm to 12 mm. Using the finite element method, the contact parameters, including the maximum contact pressure and contact area, have been evaluated in light of the Hertzian contact theory. The simulation was performed statically with dissipated energy and asymmetric behavior. The types of interaction were surface-to-surface contact and normal contact behavior. The maximum contact pressures in the inner liner (UHMWPE) at a head diameter of 28 mm and 36 mm are between 3.7-13.5 MPa and 2.7-10.4 MPa, respectively. The maximum von Mises of the inner liner, outer liner, and acetabular cup are 2.4-11.4 MPa, 15.7-44.3 MPa, and 3.7-12.6 MPa, respectively, for 28 mm head. Then the maximum von Mises stresses of the 36 mm head are 1.9-8.9 MPa for the inner liner, 9.9-32.8 MPa for the outer liner, and 2.6-9.9 MPa for the acetabular cup. A head with a diameter of 28 mm should have an inner liner with a thickness of 12 mm. Whereas the head diameter was 36 mm, an inner liner thickness of 8 mm was suitable. The contact pressures and von Mises stresses generated during this research can potentially be exploited in estimating the wear of dual-mobility artificial hip joints in general. Contact pressure and von Mises stress reduce with an increasing head diameter and inner liner's thickness. Present findings would become one of the references for orthopedic surgery for choosing suitable bearing geometric parameter of hip implant.

The influence of cooling medium and cooling channel on heat transfer of textured seal in presence of viscous dissipation

When operating at high speed, the mechanical seal produces a large amount of frictional heat on the seal face. If the heat is not dissipated in time, it could lead to the thermal failure of the seal face. In the field of tribology research, the technology of textured surface is a method to enhance the heat dissipation rate. Numerical analysis is carried out based on the SST k-ω turbulence model and the energy equation with viscous dissipation term, and the results are validated by the experimental data published in the reference. In a wide range of rotational speeds, cooling medium with varied Pr numbers is employed to confirm the performance of textured side-wall in heat transfer enhancement. The shape of the seal chamber is also changed to provide guidance for the design of the cooling channel. The results show that a larger Pr number increases the heat transfer enhancement of the textures; it is advisable to utilize a cooling channel that gradually decreases in size; and the flushing should not be perpendicular to the stator; additionally, it is important to ensure that the cooling channel is not too narrow. By means of appropriate design, the maximum temperature of seal face can be reduced by over 40 °C (22.2 %) at 20,000 rpm.

Experimental installation for wear tests of materials and coatings

On the basis of the analysis of existing tribological testing methodologies, which includes the selection of controlled wear parameters, the influence of the type of friction, contact geometry, surface roughness, the scheme of tribological research, the choice of a machine 2168UМТ for friction testing of materials is substantiated. The friction machine allows you to install three samples at the same time, change the pressure in the contact zone in a wide range, control the moment of friction, the rotation frequency of the counterbody, the number of revolutions (friction path), change the rotation frequency, respectively, the sliding speed, automatically limit the distance traveled and other functions. The method of wear is adopted according to the finger-ring scheme, linear wear is monitored using an indicator rack with a value of divisions of the measuring device of 0.001 mm. To fix the samples on the machine caliper, holders were designed and manufactured, which ensure the self-fixation of the sample on the counterbody - a spherical joint made of the rolling body of the bearing. due to the fact that the samples were pressed against the counterbody with a force corresponding to the nominal contact pressure, they were self-aligned. After the sample was self-assembled, the whole structure was fixed by tightening the nuts. The counterbody is made of a rolling bearing ring, the material is steel SHX15, the hardness of the base is HRC 61. Three devices are mounted on the caliper for permanent lubrication of the running track immediately before the approaching sample. Thus, at certain values of pressure and speed, the mode of marginal friction can be reached, which was marked by a low coefficient of friction.

AI for tribology: Present and future

AbstractWith remarkable learning capabilities and swift operational speeds, artificial intelligence (AI) can assist researchers in swiftly extracting valuable patterns, trends, and associations from subjective information. Tribological behaviors are characterized by dependence on systems, evolution with time, and multidisciplinary coupling. The friction process involves a variety of phenomena, including mechanics, thermology, electricity, optics, magnetics, and so on. Hence, tribological information possesses the distinct characteristics of being multidisciplinary, multilevel, and multiscale, so that the application of AI in tribology is highly extensive. To delineate the scope, classification, and recent trends of AI implementation in tribology, this review embarks on exploration of the tribology research domain. It comprehensively outlines the utilization of AI in basic theory of tribology, intelligent tribology, component tribology, extreme tribology, bio-tribology, green tribology, and other fields. Finally, considering the emergence of “tribo-informatics” as a novel interdisciplinary field, which combines tribology with informatics, this review elucidates the future directions and research framework of “AI for tribology”. In this paper, tribo-system information is divided into 5 categories: input information (I), system intrinsic information (S), output information (O), tribological state information (Ts), and derived state information (Ds). Then, a fusion method among 5 types of tribo-system information and different AI technologies (regression, classification, clustering, and dimension reduction) has been proposed, which enables tribo-informatics methods to solve common problems such as tribological behavior state monitoring, behavior prediction, and system optimization. The purpose of this review is to offer a systematic comprehension of tribo-informatics and to inspire new research ideas of tribo-informatics. Ultimately, it aspires to enhance the efficiency of problem-solving in tribology.

Solid lubrication performance of Ti2CTx coatings with reduced friction and extended durability

MXene research in tribology has predominantly focused on Ti3C2Tx, overlooking the untapped potential of other promising MXenes with equally intriguing properties. Thus, to enhance tribological reliability in industrial applications, Ti2CTx coatings were applied to 316 stainless steel as a solid lubricant. Using a linear ball-on-disk tribometer under 460 MPa pressure, we found that Ti2CTx coatings reduced friction by 82% and wear rate by 70% compared to uncoated steel. Advanced characterizations showed that this improved tribology is linked to nanostructured carbon-rich protective tribofilms resulting from the contact pressure-induced graphitization of Ti2CTx MXenes sheets. Our research comprehensively elucidates the tribological effectiveness of multi-layer Ti2CTx, which is pivotal to design advanced lubricants for contemporary mechanical applications.

The Tribological and Rheological Properties of Vegetable Lubricating Grease Modified of TiO2 Nanoparticles

The article presents the results of tribological and rheological research of lubricating composition modified of various content of titanium dioxide. The analysis of anti-wear properties during the test for the tested lubricating composition indicates a significant change in this parameters for lubricants modified of titanium dioxide. A change of the value of evaluated tribological parameters leads to change in the structure of the composition carried out tests and a change in the effectiveness of the tribological protection of the tribosystem. The content of the thickener, base of oil and additive in the lubricant structure affects the level of the anti-wear properties, as evidenced by the results obtained during the tribological tests presented in this article. Also, the tribological tests were carried out with the T-02 four-ball machine for the base grease, i.e. without a modifying additive, and compared with the results obtained for lubricating greases modified with various amounts of titanium dioxide. The results of welding load, limiting pressure of seizure, scuffing load, limiting load of scuffing and limiting load of wear were used to evaluate the tribological properties. Based on the results of tribological tests of vegetable lubricating compositions, it was found, that the addition of titanium dioxide changed the anti-wear and anti-seizure properties of the vegetable lubricating compositions under study. The introduction of various amount of titanium dioxide caused an increase of dynamic viscosity at lower shear rates and significant changes of viscosity in the low temperatures. The introduction of modifier led to the decrease of yield point value from content value of used additive of tested lubricating compositions.

Insights into modeling approaches for boundary- and mixed-lubricated conditions

PurposeTribological research is complex and multidisciplinary, with many parameters to consider. As traditional experimentation is time-consuming and expensive due to the complexity of tribological systems, researchers tend to use quantitative and qualitative analysis to monitor critical parameters and material characterization to explain observed dependencies. In this regard, numerical modeling and simulation offers a cost-effective alternative to physical experimentation but must be validated with limited testing. This paper aims to highlight advances in numerical modeling as they relate to the field of tribology.Design/methodology/approachThis study performed an in-depth literature review for the field of modeling and simulation as it relates to tribology. The authors initially looked at the application of foundational studies (e.g. Stribeck) to understand the gaps in the current knowledge set. The authors then evaluated a number of modern developments related to contact mechanics, surface roughness, tribofilm formation and fluid-film layers. In particular, it looked at key fields driving tribology models including nanoparticle research and prosthetics. The study then sought out to understand the future trends in this research field.FindingsThe field of tribology, numerical modeling has shown to be a powerful tool, which is both time- and cost-effective when compared to standard bench testing. The characterization of tribological systems of interest fundamentally stems from the lubrication regimes designated in the Stribeck curve. The prediction of tribofilm formation, film thickness variation, fluid properties, asperity contact and surface deformation as well as the continuously changing interactions between such parameters is an essential challenge for proper modeling.Originality/valueThis paper highlights the major numerical modeling achievements in various disciplines and discusses their efficacy, assumptions and limitations in tribology research.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-03-2023-0076/

Vastness of Tribology Research Fields and Their Contribution to Sustainable Development

Tribology is related to all studies on friction, wear, and lubrication. One of the main aims of these studies is a reduction in friction and wear. Tribology is extremely vast, being also multidisciplinary and interdisciplinary. Therefore, it is very difficult to organize the several tribology subjects in an unique way and different classifications have been proposed by different authors. In this work, several subjects treated by tribology are reviewed and organized in six branches: Fundamental Tribology, Tribology of Materials and Lubricants, Micro and Nanotribology, Industrial Tribology, Biotribology, and New Frontiers of Tribology. The main subjects treated by the six branches are briefly reviewed in this paper in order to highlight the vastness of tribology and its important contribution to sustainability. Particularly, friction and wear reductions are strictly related to greater efficiency and material saving, which means less energy losses and material wastes, less pollution and therefore a more sustainable life according to the sustainable development goals. The connections among the latter and the several different tribological subjects are discussed.

Recent Advances in Bio-Tribology From Joint Lubrication to Medical Implants: A Review

Bio-tribology, the study of lubrication, wear, and friction in biological systems, has made recent strides in the lubrication of medical implants and joints. This comprehensive review discusses the most recent developments in bio-tribology, with an emphasis on the transition from basic science to medical engineering applications. An overview of bio-tribology and its increasing significance in medicine commences the study. Following this, recent research on the composition of synovial fluid and its function in minimizing friction in natural joints is discussed. Medical implant tribology, including degradation issues in dental prostheses and joint replacements, is then addressed. This study investigates the manner in which surface modifications and coatings improve the tribological performance of medical implants. It emphasizes recent developments in material science and engineering. This article emphasizes the significance of minimizing implant material degradation in relation to the functionality and longevity of biomedical devices. Following this, digital models, simulations, and state-of-the-art imaging techniques that have propelled bio-tribology forward are highlighted. In addition to proposing potential research avenues to overcome the current obstacles, the article highlights the interdisciplinary nature of bio-tribology and urges collaboration among tribology, materials science, and biomechanics researchers.

Improvement of tribological parameters of carbon-carbon material by modification of the friction surface

The results of high-temperature tribological research of carboncarbon material at friction on heat-resistant stainless steel 40Х13 in the temperature range from +20 to +700 °С are presented. Friction surface modifiers change the structure of the friction surface of carbon-carbon material CCCM-2D, improve its antifriction properties, and reduce the friction coefficient. The structurally modified friction surface provided by modifiers PTFE, SnSe-PTFE, and InSb-Se-PTFE achieves friction coefficient values of 0.08 to 0.15 in the temperature range of +300 to +500 °C. These results are intended for use in the creation of sliding bearings for operation at high temperature, as they show that structurally modified friction surfaces of carbon-carbon material can withstand high temperatures without losing their friction-reducing abilities.

Tribological studies of materials for sliding bearings when lubricated with hydraulic fluid

Tribological research of materials BrOPh6.5-0.15, PH4M paired with 40X steel and lubricated with hydraulic fluid AMh-10 showed good antifriction properties. The results of the research on the influence of load, speed and temperature on the coefficient of friction of materials: BrOPh6.5-0.15 and PH4M when lubricated with AMh-10 hydraulic fluid. At a load of 0.5447 MPa, the coefficient of friction of BrOPh6.5-0.15 material at a temperature of 90°C is 1.58 times higher, and at a load of 2.003 MPa, the coefficient of friction of BrOPh6.5-0.15 material is 2.85 times higher than the coefficient of friction of BrOPh6.5-0.15 material at a temperature of 20°C. Materials BrOPh6.5-0.15 and PH4M are promising for application in plain bearings of pumps pumping hydraulic fluid AMh-10.

TRIBOLOGY OF DRILL BITS IN THE GEOTHERMAL INDUSTRY: A LITERATURE REVIEW

Energy from the earth’s heat is critical to the energy supply of countries with this resource. This literature review highlights the tribology applied to drill bits in the geothermal industry. Facing a diverse geological environment, drill bits are critical to energy efficiency, with significant friction, wear and lubrication challenges. This paper addresses the complexity of drill bit interaction with diverse geothermal formations, highlighting the importance of understanding tribological phenomena. Advances in materials and coatings, such as composites, heat-resistant alloys and ceramic coatings, are explored, along with innovative geometric design strategies. Attention on lubrication, cooling and continuous monitoring systems highlights the quest for efficiency and extended drill bit life. This review provides a comprehensive overview of advances in bit tribological research in the geothermal industry, identifying emerging trends and critical challenges for the sustainable development of this form of renewable energy.

MoS2 Nanomaterials as Lubricant Additives: A Review

Improving the lubricating properties of base oils through additives is a crucial objective of tribological research, as it helps to reduce friction and wear of materials. Molybdenum disulfide (MoS2) is a 2D nanomaterial with excellent tribological properties that is often used as a lubricant additive. Several studies have been conducted on the preparation and utilization of MoS2 and its nanocomposites as lubricant additives. This paper reviews the research progress on MoS2 nanomaterials as lubricant additives. It firstly introduces various synthesis methods of MoS2 nanomaterials while focusing on the preparation of nano-MoS2 as lubricant additives. It then summarizes the dispersion stability of nano-MoS2 in lubricating oils which has been paid extensive attention. Moreover, this paper reviews and discusses the tribological properties of nano-MoS2 and its various composites as lubricant additives. The possible anti-wear and friction reduction mechanisms of nano-MoS2 and its composites are also discussed. Finally, this paper presents the challenges faced by nano-MoS2 additives in the field of lubrication and the prospects for future research in view of previous studies.

A hybrid data-driven approach for the analysis of hydrodynamic lubrication

The application of data mining technology has intensively advanced tribology research. While recent lubrication studies have highlighted the importance of data mining, researchers have not fully bridged the gap between massive lubrication data and intrinsic lubrication mechanisms. Thus, by revisiting lubrication modelling from the data-driven and physics-informed perspectives, we aim to construct a hybrid approach for hydrodynamic lubrication classification and prediction, where data-driven methods are combined with physics-informed approaches to achieve a fast and accurate prediction of the hydrodynamic lubrication scenario. Our approach will spur the application of data mining methods in lubrication studies.