Tribological Analysis Research Articles

Tribological analysis of rotor system startup considering deformations of high elastic rubber bushings and grease lubricated plastic bearings

To achieve a compact design, reduced noise, and extended operational lifespan of the air conditioner indoor unit, a novel motor rotor system was implemented. This system utilizes three engineering plastic bearings, encased in high-elasticity rubber bushings and lubricated with grease. Yet, the absence of a simulation model that accurately represents the structural and material properties of this bearing-rotor assembly hampers the precise evaluation of how design parameters influence system performance. As such, in the present study, an innovative tribo-dynamics model was established using a coupling approach that integrates dynamics and tribology. This model encompasses a 4-degree-of-freedom rotor dynamics framework and a grease elastohydrodynamic model, which accounts for the deformation of both rubber bushings and plastic bearings. Utilizing this tribo-dynamics model, the effects of the elastic modulus of the bushing on the tribological properties of the system were explored. The results show that a small elastic modulus of the bushing effectively reduced the local high contact pressure between the journal and the bearing during startup. However, the elastic modulus cannot be excessively low, as it would adversely affect the range of journal motion and the film thickness under rated operating conditions.

Tribological analysis and machine learning modeling of nickel-coated graphite reinforced A206 metal matrix composites

Tribological analysis and machine learning modeling of nickel-coated graphite reinforced A206 metal matrix composites

Mechanical and Tribological analysis of C355 Aluminium Alloy/Graphene oxide (GO) /Bio-silica (BS) Hybrid Nanocomposite

Mechanical and Tribological analysis of C355 Aluminium Alloy/Graphene oxide (GO) /Bio-silica (BS) Hybrid Nanocomposite

Tribological Analysis of Surface Textures in Porcelain Tiles for Enhancing Pedestrian Walkway Safety

Due to their durability and aesthetic appeal, porcelain tiles have become a staple in modern construction and interior design. However, the persistent challenge of mitigating slip hazards, particularly in moist conditions, remains a critical concern for pedestrian safety. This study investigates the slip resistance performance of porcelain tiles, focusing on the influence of varying surface textures. The study clarifies the intricate relationship between surface texture and slip resistance through comprehensive dynamic friction tests involving four distinct porcelain tile samples and three different shoe samples conducted under arid, damp, and lathered conditions. While dry conditions showcase robust traction, moist environments underscore the significance of surface textures in enhancing grip. Moreover, the study introduces an operational scale of surface roughness, delineating optimal texture boundaries for maximal slip resistance. The implications of these findings extend beyond mere material characterisation, offering actionable insights for architects, designers, and safety professionals to enhance pedestrian safety in diverse settings. By bridging the gap between material science and real-world safety concerns, this research paves the way for innovative porcelain tile designs that prioritise safety without compromising aesthetic appeal.

Microstructure and high temperature tribological behavior of nickel-based superalloy with addition of revert

The recycling of revert plays a crucial role in cost-efficiency and green manufacturing of superalloy. In this study, optical microscopy, scanning electron microscopy coupled with energy dispersive spectroscopy, tensile test, and tribological analysis were employed to investigate the microstructure, mechanical properties, and tribological behaviors of vacuum induction melted superalloys of 100% original material (Sample 1) and 40% original material + 60% revert (Sample 2). Dry sliding tests were conducted at 300 and 730 °C. The addition of revert promotes microstructure refinement, hardness increase, and carbide formation, at the cost of 18.5% ductility loss. During the high-temperature dry sliding process, abrasive, adhesive, and oxidative wear mechanisms were observed on the contact surfaces. Sample 2 exhibited a lower wear rate and coefficient of friction at both 300 and 730 °C. Additionally, a more continuous and wear-resistant tribolayer was formed on the wear track of Sample 2, effectively mitigating matrix oxidation compared to Sample 1. At 730 °C, a thick tribolayer developed on the wear surface of Sample 2, characterized by a hard and wear-resistant glaze layer on the outermost surface. The continuous sliding induced matrix heating, which facilitates recrystallization in the subsurface of Sample 2, induced by increased inclusions and carbides from the revert. The analysis of wear debris further illustrated the variations of wear mechanism at different temperatures. These findings are meaningful for understanding the high-temperature behavior of superalloys and optimizing alloy recycling process.

Micromechanical and Tribological Performance of Laser-Cladded Equiatomic FeNiCr Coatings Reinforced with TiC and NbC Particles.

This paper discusses a comparative micromechanical and tribological analysis of laser-cladded equiatomic FeNiCr coatings reinforced with TiC and NbC particles. Two types of coatings, FeNiCr-TiC (3 wt.% TiC) and FeNiCr-NbC (3 wt.% NbC), were deposited onto an AISI 1040 steel substrate by means of short-pulsed laser cladding. The chemical composition, microstructure, and micromechanical and tribological characteristics of the coatings were systematically investigated via optical and scanning electron microscopy, Raman spectroscopy, and mechanical and tribological tests. The average thicknesses and compositional transition zones of the coatings were 600 ± 20 μm and 150 ± 20 μm, respectively. Raman spectroscopy revealed that both coatings are primarily composed of a single FCC γ-phase (γ-FeNiCr). The FeNiCr + 3 wt.% TiC coating exhibited an additional TiC phase dispersed within the γ-FeNiCr matrix. In contrast, the FeNiCr + 3 wt.% NbC coating displayed a more homogeneous distribution of finely dispersed NbC phase throughout the composite, leading to enhanced mechanical behavior. Micromechanical characterization showed that the FeNiCr + 3 wt.% NbC coating possessed higher average microhardness (3.8 GPa) and elastic modulus (180 GPa) compared to the FeNiCr + 3 wt.% TiC coating, which had values of ~3.2 GPa and ~156 GPa, respectively. Both coatings significantly exceeded the AISI 1040 steel substrate in tribological performance. The FeNiCr + 3 wt.% TiC and FeNiCr + 3 wt.% NbC coatings exhibited substantial reductions in both weight loss (37% and 41%, respectively) and wear rate (33% and 42%, respectively) compared to the substrate material. These findings indicate that more finely dispersed NbC particles are better suited for hardening laser-cladded equiatomic FeNiCr-NbC coatings, making them advanced candidates for industrial applications.

Environmentally Acceptable Lubricants for Stern Tube Application: Shear Stability and Friction Factor

Stern tube lubricants are essential in maritime operations, safeguarding ship propeller shafts from wear and corrosion while ensuring efficient propulsion. Their role in reducing friction and maintaining system integrity is critical. With growing environmental concerns, the adoption of environmentally acceptable lubricants (EALs) for stern tubes has gained importance, balancing operational performance with environmental protection. This study investigates the rheological and tribological properties of EALs formulated for ship propeller stern tube applications. The primary focus is on comparing these EALs with conventional mineral oils to assess their suitability in marine environments. EALs are increasingly favored due to their biodegradability and reduced environmental impact. Key parameters such as shear stability, friction factor, and temperature dependency were evaluated using a range of experimental methods including rotational viscometry and tribological analysis. The results indicate that the newly formulated EALs based on synthetic esters exhibit the highest viscosity index, a higher range of shear stability, and lower friction factors, compared to commercially available mineral oils, especially under varying operational conditions. These findings contribute to the ongoing efforts to promote eco-friendly lubricants in maritime industries, aligning with global environmental protection initiatives.

Tribofilm distribution and tribological analysis of piston ring-cylinder liner interfaces under realistic engine conditions

The study investigates tribofilm distribution and tribology performance on piston ring-cylinder liner surfaces under realistic internal combustion (IC) engine conditions. By examining the effects of load, temperature, and oil film thickness ratio, the research reveals that the tribofilm is significantly greater on the cylinder liner surface compared to the piston ring surface. The findings highlight that a specific excitation pressure is necessary for tribofilm formation. An oil film thickness ratio of 1.8041 is evaluated as an accurate boundary for tribofilm distribution on the cylinder liner surface. These insights provide valuable data for designing piston ring-cylinder liner interfaces and improving IC engine performance.

WSCF coatings tested under various environmental conditions: A multivariate tribological analysis

This study examines the influence of carbon (C) and fluorine (F) on the tribological and mechanical properties of WSCF coatings. WSCF-coated substrates were prepared with varying levels of C (10.4 to 18.7 at%) and F (5.3 to 9.3 at%) using DC reactive magnetron sputtering. Tribological performance was evaluated at 25 °C and 200 °C in dry and lubricated conditions. Alloying led to thicker, more amorphous, denser, and smoother coatings. An exceptional coefficient of friction (COF) as low as 0.008 was observed for WSCF2 (15.4 at% C and 9.3 at% F). Principal component analysis (PCA) revealed high F-doped coating in WSCF2 demonstrated improved tribological performance, resulting in a 38 % reduction in COF at 25 °C and dry conditions.

Effect of heat treatment on microstructure and wear properties on Binder Jetting Additive manufactured M2 High-Speed steel

In this study, the influence of heat treatments (annealing at 1175 °C, sub-zero at −80 °C, and triple tempering at 565 °C) of Binder Jet Additive Manufactured (BJAM) M2 grade HSS on the microstructure and tribological properties are investigated and were compared with that of conventionally manufactured samples. The residual austenite was transformed into martensite phase upon heat treatment. The tribological analysis was performed using a pin-on-disc experiment for 40 N, 50 N, and 60 N loads. It was observed that the heat-treated BJAM samples exhibited 11.5 %, 7.5 %, and 5.5 % higher specific wear resistance compared to the as-sintered samples. The enhancement in the wear resistance is primarily due to the presence of metal carbide precipitates in the heat-treated sample.

Tribological Analysis of Fused Filament Fabrication PETG Parts Coated with IGUS

Tribological Analysis of Fused Filament Fabrication PETG Parts Coated with IGUS

Thermal kinetic, mechanical and wear properties of glass fiber reinforced polyamide 6 thermoplastic composites

AbstractPolyamide 6 (PA6) thermoplastic‐based composites are often used in automobile, aerospace, marine, and biomedical applications. Here, PA6 and its composites with varied chopped glass fiber (GF) concentrations of 5, 10, and 20 mass% were fabricated by injection molding. The specimens were characterized by structural, thermal kinetic, mechanical, as well as tribological analyses. Tribological performance was evaluated in dry pin‐on‐disc test apparatus with three different levels of time, speed, and load factors. The PA6/GF composites showed high decomposition activation energy compared to pure PA6. Thermal activation, Ea increased to 46.16% with increasing of GF content up to 10 mass% in the composites compared to PA6. PA6/5GF exhibited best mechanical properties (e.g., strength = 44.46 MPa and Hardness = 45.2). Addition of GF in PA6 significantly improved tribological properties, coefficient of friction (COF) and specific wear rate (WR) besides thermal stability and mechanical properties of the composites. Especially, COF and WR of PA6/5GF composite decreased by 17%–65% and 68%–92%, respectively, compared to PA6. ANOVA statistical results determined the significant contribution of the tribological factors to the performance metrics of the composites for COF and WR. Therefore, the PA6/5GF composite would highly be useful for tie‐rod gears and bearings as a crucial structural component in automotive bodywork.

An Investigation of the Effect of Novel Mono/Bi-Layered PVD-Coated WC Tools on the Machinability of Ti-5Al-5V-5Mo-3Cr.

The Ti-5Al-5V-5Mo-3Cr (Ti-5553) alloy is a relatively novel difficult-to-cut material with limited machinability and tool life analysis available in the literature, and hence requires further investigation. This study focuses on the machining and tribological performance of Ti-5553 under high-speed finish turning (150 m/min, 175 m/min, and 200 m/min) via novel mono/bi-layered PVD-coated WC tools. A base AlTiN coating is used as the reference monolayer coating, with AlCrN, diamond-like ta-C, and TiAlSiN coatings each deposited on top of a base AlTiN coating, totaling four separate coated tools (one monolayer and three bi-layer). Tool life, cutting forces, workpiece surface quality, and tribological chip analysis are among the subjects of investigation in this study. Overall, the AlTiN/AlCrN coated tool outperformed all the other combinations: an improvement of ~19% in terms of tool life in reference to the base AlTiN coating when averaging across the three speeds; lowest surface roughness values: ~0.30, 0.33, and 0.64 µm; as well as the lowest chip back surface roughness values: ~0.80, 0.68, and 0.81 µm at 150, 175, and 200 m/min, respectively. These results indicate that the AlTiN/AlCrN coating is an excellent candidate for industrial applications involving high-speed machining of Ti-5553.

Tribological, mechanical, and thermal properties of nano tricalcium phosphate and silver particulates reinforced Bis-GMA/TEGDMA dental resin composites

The proposed study is based on fabricating a hybrid dental composite of nano tricalcium phosphate and silver nanoparticles with resin matrix. Silver nanoparticles (20 wt%) and tricalcium phosphate (0–4 wt%) were incorporated in Bis-GMA/TEGDMA resin matrix. Photo initiator and accelerator were also employed for the polymerization of dental composites. Wear or tribology analysis of dental composites was performed on pin on disc setup. Physical, thermal, and mechanical properties were investigated under ASTM parameters. Void, water solubility, and sorption increased with an increment of filler loading. Maximum polymerization shrinkage 3.85 ± 0.02 % and depth of cure 2.57 ± 0.12 mm indicated by control sample TAg0. Taguchi L25 orthogonal array was used as a design of experiment (DOE) for wear analysis. TGA revealed the thermal stability in the form of: TAg0 > TAg1 > TAg2 > TAg3 > TAg4 in the range of 22–100 ̊C. In conclusion, the direct restorative material composed by the hybrid showed good mechanical and physical properties and potential thermal results, widening the scope of Ag and tricalcium phosphate in the dental composites.

Correlation of rheology and oral tribology with sensory perception of commercial hazelnut and cocoa-based spreads.

This study examined the effects of spread formulation and the structural/lubricant properties of six different commercial hazelnut and cocoa spreads on sensory perception. Rheology, tribology, and quantitative descriptive analysis (QDA) was assessed by also evaluating the correlation coefficients between the quality descriptor and the rheological and textural parameters. The viscosity was evaluated at different temperatures to better simulate conditions before and after ingestion. Tribological analysis was executed at 37°C to mimic the human oral cavity. The effect of saliva presence and the number of runs on tribological behaviors was investigated. Moreover, textural, calorimetric, and particle size distribution measurements were performed to reinforce the correlation between structural/thermal parameters (e.g., firmness, stickiness, sugar melting point) and sensory aspects. "Visual viscosity," defined as a sensory attribute evaluated prior to consumption, negatively correlated with apparent viscosity measured at 20°C and 10 s-1, whereas "body," defined during oral processing and related to creaminess, positively correlated with apparent viscosity measured at 37°C and 50 s-1. These attributes were mainly influenced by particulate microstructure and solid volume fraction within the formulation. Textural stickiness positively correlated with sensory "adhesiveness" and was related to fat composition and milk powder addition, while "sweetness" was related to sucrose content and sugar melting enthalpy. Tribological data provided meaningful information related to particle-derived attributes, as well as after-coating perception (fattiness/oiliness), thus better predicting food evolution during oral consumption.

Combination of a Viscoelastic and a Tribological Analysis of a Low‐Density Polyethylene with a High Degree of Cross‐linking

Combination of a Viscoelastic and a Tribological Analysis of a Low‐Density Polyethylene with a High Degree of Cross‐linking

Mechanism and suppression of friction-induced vibration in catenary-pantograph system

An unexplained instability phenomenon in railways is known to be caused by sliding friction in a catenary-pantograph system at low speeds. This is an important engineering problem because this instability phenomenon contributes to increased wear of contact wires and requires a train driver to confirm safety, which leads to train delays. Tribological analyses have found an increase in the friction coefficient at low speeds. Pantograph models based on the finite element method, multibody dynamics, and pin-disk model have been proposed for kinematic analyses. However, the mechanism is still uncertain, and no experimental investigations have been conducted. In this study, experimental and numerical investigations are conducted on the instability phenomenon caused by sliding friction. A method for estimating the friction coefficient for an actual pantograph is proposed and applied to experimentally investigate the instability phenomenon. A dynamic model is constructed based on various experiments. The frequency and the stable-unstable boundary of the instability phenomenon obtained in the simulations agree with those obtained in the experiment. From the dynamic model, it is found that the instability is a flutter-type instability caused by the asymmetry of the stiffness matrix due to Coulomb friction. Countermeasures for preventing the instability phenomenon based on the determined mechanism are proposed, and their effectiveness is verified by simulations and experiments. The results could contribute to the design of new pantographs to improve stability and the development of countermeasures for existing pantographs that experience instability.

Comprehensive investigation of microwave sintered AlCoCrFeNi/Ti-6Al-4V composite: Microstructural insights, mechanical properties, and tribological performance

Ti-6Al-4 V is an extensively used and highly versatile titanium alloy. It is renowned for its lightweight-to-strength ratio, excellent biocompatibility, and corrosion resistance. The pursuit of advanced materials with enhanced mechanical strength, and wear resistance has led to the exploration of high entropy alloys (HEA) as particle reinforcements. This study combines Ti-6Al-4 V with AlCoCrFeNi HEA at different weight compositions (0 %, 2 %, 4 %, 6 %, 8 %) to create novel composites with tailored properties. The composites were subjected to density, microhardness, tensile, and pin-on-disc tests to evaluate mechanical and tribological properties. Microstructural analysis revealed that microwave sintering has enhanced densification and resulted in uniform dispersion of HEA particles within the Ti-6Al-4 V matrix. The XRD and EBSD analysis revealed the presence of BCC structure in the composite. 8 wt%-AlCoCrFeNi/Ti-6Al-4 V sample exhibited an impressive 81.66 % increase in microhardness and 21.23 % in yield strength, compared to the base sample. Furthermore, noteworthy reductions of 45 % in wear rate and 40 % in coefficient of friction (COF) when subjected to tribological analysis. The worn surface revealed the presence of oxide layer formation at elevated sliding velocity and distance which resulted in reduced wear rate.

Numerical Study of Coolant Flow Phenomena and Heat Transfer at the Cutting-Edge of Twist Drill

Cutting tool coolant channels play a pivotal role in machining processes, facilitating the efficient supply of cooling agents to high-stress areas and effective heat dissipation. Achieving optimal cooling at the tool’s cutting-edge is essential for enhancing production processes. Experimental investigations into tribological stress analysis can be limited in accessing complex tool–workpiece contact zones, prompting the use of numerical modelling to explore fluid dynamics and tribology. In this study, the coolant flow dynamics and heat dissipation in drilling operations were comprehensively investigated through computational fluid dynamics (CFD) modelling. Four twist drill models with varying coolant channel arrangements were studied: standard model drill, standard model drill with notch, profile model drill, and profile model drill with notch. Two distinct approaches are applied to the coolant inlet to assess the impact of operating conditions on fluid flow and heat dissipation at the cutting-edge. The findings emphasize that cutting-edge zones have insufficient coolant supply, particularly in modified drill models such as the standard model drill with notch and profile model drills with and without notch. Moreover, enhanced coolant supply at the cutting-edge is achieved under high-pressure inlet conditions. The standard model drill with a notch exhibited exceptional performance in reducing thermal load, facilitating efficient coolant escape to the flute for improved heat dissipation at the cutting-edge. Despite challenges like dead zones in profile models, the standard-with-notch model yielded the most promising results. Further analyses under constant pressure conditions at 40 and 60 bar exhibited enhanced fluid flow rates, particularly at the cutting-edge, leading to improved heat dissipation. The temperature distribution along the cutting-edge and outer corner demonstrated a decrease as the pressure increased. This study underscores the critical role of both coolant channel design and inlet pressure in optimizing coolant flow dynamics and heat transfer during drilling operations. The findings provide valuable insights for designing and enhancing coolant systems in machining processes, emphasizing the significance of not only coolant channel geometry but also inlet pressure for effective heat dissipation and enhanced tool performance.

Enhancing performance of Prosopis juliflora fiber reinforced epoxy composites with silane treatment and Syzygium cumini filler

The utilization of natural fibers and fillers in composite materials has gained significant attention for their potential to enhance mechanical, thermal, and tribological properties while promoting sustainability. In this study, Prosopis juliflora fiber (PJF) reinforced epoxy composites, treated with silane and incorporating Syzygium cumini filler (SCF), were investigated to assess their performance across various parameters. The composites were subjected to comprehensive mechanical, tribological, thermo-gravimetric, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), 3D profilometer, and morphology studies to elucidate the effects of silane treatment and SCF content on composite properties. The results of the mechanical characterization revealed significant improvements in tensile strength, impact strength, and microhardness in silane-treated composites with higher SCF content compared to untreated samples and those with lower SCF content. Specifically, the ST/SCF3 composite exhibited the highest values, with a tensile strength of 118.65 ± 4.63 MPa, impact strength of 27.83 ± 1.96 kJ/m2, and microhardness of 91.63 ± 2.84 HV. Tribological analysis indicated enhanced wear resistance and reduced coefficient of friction in silane-treated composites with higher SCF content, with the ST/SCF3 composite demonstrating the lowest wear loss (62 μm) and frictional force (5.2 N). Thermal characterization revealed improved thermal stability in silane-treated composites, particularly in the ST/SCF1 and ST/SCF3 formulations, suggesting increased resistance to temperature-induced degradation.