Friction Behavior Research Articles

Numerical simulation of the tribological behavior of cylinder liners containing hybrid textures (stochastic dimples and honing grooves)

Abstract This work aims to optimize the surface textures of two-stroke engine cylinder liners through numerical simulation. A mirror-like liner with stochastic texture patterns resulting from localized “peak outs” formed in the honing step of hard chrome coating was used as the reference surface. Honing grooves were digitally superimposed onto the reference surface, and the effects of the groove crossing angle (α), depth (d p), width (w), and density (d e) on the mixed lubrication and friction behavior of the piston/cylinder liner tribosystem were evaluated. The simulations used a deterministic modelling approach that couples a hydrodynamic model with an asperity contact model at the microscopic roughness scale. The optimal simulation results were obtained for grooves with α = 40°, d e = 0.15, w = 15 μm and d p = 1.5 μm. However, even the most favorable textured configuration showed inferior lubrication performance compared to the reference surface. These findings suggest that the stochastic texture resulting from mirror-like honing already provides advantageous lubrication conditions, making the addition of honing grooves unnecessary for the cylinder liners analyzed in this study.

The emulsion-filled gels with different fat contents exhibit various friction behavior and dynamic fat-related texture perception at different temperatures

The emulsion-filled gels with different fat contents exhibit various friction behavior and dynamic fat-related texture perception at different temperatures

Friction and wear behavior of atmospheric plasma sprayed Ni-50at% Bi coating at room temperature to 400 °C

Friction and wear behavior of atmospheric plasma sprayed Ni-50at% Bi coating at room temperature to 400 °C

High-temperature friction and wear behaviors of the laser in-situ synthesized VB2 reinforced NiCrBSi alloy-based composite coating

High-temperature friction and wear behaviors of the laser in-situ synthesized VB2 reinforced NiCrBSi alloy-based composite coating

Characterization of frictional behavior of fiber reinforced composites during forming: A review

Characterization of frictional behavior of fiber reinforced composites during forming: A review

Investigation of the local friction behavior in the secondary shear zone by coupling of chip formation and microscale contact simulation

Investigation of the local friction behavior in the secondary shear zone by coupling of chip formation and microscale contact simulation

Dynamic friction behaviors of slip surfaces in granite and implications for large rapid rockslides with long runouts on the southeastern Tibetan Plateau: Constraints from an experimental investigation

Dynamic friction behaviors of slip surfaces in granite and implications for large rapid rockslides with long runouts on the southeastern Tibetan Plateau: Constraints from an experimental investigation

Effect of temperature on the friction performance and mechanisms of Si3N4 and steel interfaces in oil-lubricated term rolling bearing

Purpose This study/paper aims to the tribological behavior and underlying mechanisms of various bearing material. With advancements in aerospace technology, conventional steel-bearing materials face challenges in meeting the demands of high loads, wide temperature ranges and other extreme operating conditions. Due to their exceptional physical and chemical properties, ceramic bearings have emerged as an ideal alternative. However, their service performance differs significantly from that of traditional steel bearings. Design/methodology/approach This study investigates the friction and wear characteristics of lubricants used in steel and ceramic bearings. The frictional behavior of aerospace lubricants is evaluated across four material pairings at temperatures ranging from ambient to 170°C. Findings The results demonstrate that aerospace lubricants exhibit superior tribological performance in Si3N4-based systems, characterized by lower coefficients of friction and reduced wear compared to steel/steel systems. This enhanced performance is primarily attributed to the high thermal stability of Si3N4. At 170°C, the coefficient of friction and wear rate in Si3N4 systems are markedly lower than those in steel/steel systems. Specifically, at 170°C, the disk wear rate of the Si3N4/M50 system was reduced by 75%, 74.5% and 65.7% relative to the GCr15/GCr15, M50/M50 and M50/M50NiL systems, respectively. Originality/value This paper elucidates the tribological behavior and underlying mechanisms of various bearing steel/steel and ceramic/steel material combinations. The findings aim to offer valuable theoretical guidance and experimental reference for the practical application of ceramic/steel bearings. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-03-2025-0130/

Unveiling the mechanical, friction, and wear responses of SiC+Gr reinforced copper hybrid composites developed by powder metallurgy (P/M) technique

Abstract The mechanical, friction, and wear properties are very crucial in applications such as bearing materials, carbon bushes, and electrical contacts. The present study involved the fabrication of copper-based self-lubricating hybrid composites, for which copper was chosen as matrix, graphite (Gr) and silicon carbide (SiC) were selected as reinforcements. These hybrid composites were synthesized using the powder metallurgy (P/M) a zero waste technique, where an equal quantity of graphite (Gr) and silicon carbide (SiC) were reinforced in the matrix. There were four samples prepared and designated as S1, S2, S3, and S4. Then the microstructural, mechanical, friction, and wear behaviours of the fabricated hybrid composites were studied. The XRD evaluation of composites indicates the absence of any intermediary reaction taking place between the copper and reinforcing particles. The micrographs of the composites displayed a consistent dispersion of reinforcement particles throughout the copper matrix. The pin-on-disk tribometer was utilised to perform dry sliding wear experiments under loads varying from 10 to 30 N, sliding velocities of 1-2 m/s, and constant sliding distances of 2000 m. The addition of 3 wt. % of both graphite and SiC reinforcement results in a hardness of 93.6 HV, which is 60.36% greater than the hardness of pure copper (56.5 HV). Studies indicate that the wear rate and coefficient of friction (COF) of composites decrease as the amount of reinforcement increases. Specifically, the composite containing 9 wt. % of both graphite and SiC demonstrates the lowest level of wear. The wear rate exhibited an upward trend with the applied load and sliding velocity for each material. The examination of the deteriorated surface also indicates that delamination is the main process of deterioration for pure copper specimens. SiC and graphite-reinforced composites have experienced different types of wear mechanism, such as adhesive, abrasive, oxidative, and delamination wear.

Modelling of turbulent shear stress in vertical bubbly flows at low void fractions and low flow velocities

Modelling wall shear stress in two-phase bubbly flow is crucial for a variety of engineering applications, including multiphase propulsion systems, heat exchangers, and advanced cooling systems. The interaction between the liquid and gas phases, particularly in bubbly flow regimes, significantly affects performance, efficiency, and safety. In such flows, the near-wall region is characterised by high void fractions and sharp gradients in turbulent shear stress, requiring a more detailed understanding of frictional behaviour to improve pressure drop predictions in turbulent gas–liquid flow systems. This study focuses on vertical two-phase bubbly flows at relatively low turbulence regimes, with flow velocities below 2 m/s in water. To address the challenges associated with these flow conditions, the turbulent viscosity in bubbly flow according to the model proposed by Sato is considered. The analysis in the near-wall zone has led to the development of a relatively simple formulation for turbulent shear stress in the bubbly boundary layer, expressed as a function of the turbulent shear stress in single-phase flow, The bubble size (db), The void fraction (α), dimensionless distances to the wall and the constants κSP and CSP for the logarithmic law in two-phase flow. This model is validated using experimental data from the literature on bubbly flows and shows improved accuracy by explicitly accounting for the dynamic interaction between bubbles and the wall. The results demonstrate excellent agreement between experimental data and numerical predictions of turbulent friction, highlighting the model's reliability. The enhanced accuracy of the proposed model has significant implications for optimising systems where precise control of two-phase flow behaviour is essential. These findings pave the way for more reliable design and optimisation of high-performance systems, enabling better prediction and management of wall shear stress in complex bubbly flow regimes.

Mechanical Damage Prediction for Artillery Steel Considering High-Temperature Friction and High-Speed Impact

High-temperature friction and high-speed impact are the primary sources of mechanical damage to artillery steel, severely restricting the interior ballistic properties and service life of barrel weapons. A hydrodynamic friction model is first proposed to express the high-temperature friction behavior between the rotating band and the barrel. Additionally, this article deduces a contact force model to describe the high-speed impact behavior between the center band and the barrel. The general expression of mechanical damage can be obtained by the hydrodynamic friction and contact force models. Meanwhile, this article calculates the frictional coefficient and contact force distribution during the artillery launching combined ABAQUS with polynomial chaos expansion. The experimental verification of the hydrodynamic friction and contact force models is organized, and the detailed assessments show that the frictional coefficient and contact force responses have good agreement with experimental data. Finally, this article gives the mechanical damage evolution based on the general mechanical damage model. The mechanical damage of the barrel chamber is mainly located at the muzzle and 1/6 barrel length position from the beginning of rifling.

Machine-Learning-Driven Analysis of Wear Loss and Frictional Behavior in Magnesium Hybrid Composites

The wear loss and frictional characteristics of magnesium-based hybrid composites reinforced with boron carbide (B4C) particles and graphite filler were the main subjects of the investigation. Key parameters, including reinforcement content (0–10 wt%), applied load (5–30 N), sliding speed (0.5–3 m/s), and sliding distance (500–3000 m), were varied. Data-driven machine learning (ML) algorithms were utilized to identify complex patterns and predict relationships between input variables and output responses. Five distinct machine learning algorithms, Artificial Neural Network (ANN), Random Forest (RF), K-Nearest Neighbor (KNN), Gradient Boosting Machine (GBM), and Support Vector Machine (SVM), were employed to analyze experimental tribological data for predicting wear loss and coefficients of friction (COFs). The performance evaluation showed that ML models effectively predicted friction behavior and wear behavior of magnesium-based hybrid composites using tribological test data. A comparison of model performances revealed that the Gradient Boosting Machine (GBM) provided superior accuracy compared to other machine learning models in predicting both wear loss and the coefficient of friction. Additionally, feature importance analysis indicated that the graphite weight percentage was the most significant influence in predicting the coefficient of friction and wear loss characteristics.

Discrete Element Modeling of Fracture Behavior and Stress Analyses in Thermal Barrier Coatings During Wear Tests

Abstract Thermal barrier coatings (TBCs) are extensively used in various industrial applications due to their high-temperature thermal insulation and environmental protection when applied to the surfaces of engine components. Wear and frictional behaviors are important when the TBCs are subject to foreign object contact. To characterize the wear performance of TBCs, this study presents an improved discrete element method (DEM)-based model to investigate the wear mechanisms induced by friction at the microscopic level. The studied TBCs consist of a ceramic top layer, a metallic bond coat, and a high-temperature nickel superalloy as the substrate, with the assumed thicknesses of 0.25 mm, 0.15 mm, and 0.8 mm, respectively. The simulation results indicate that the wear of the coating occurs in four stages: initial microcrack formation stage, particle detachment and small pit formation stage, extensive detachment and increased pit formation stage, and intensified extrusion and surface damage stage. The growth trend of crack and bonding failure energy resembles an “S” shape. The calculated coefficients of friction show a good agreement with experimental data in terms of normal force dependence. Using the Hertzian contact theory, the DEM shows that the maximum stress-induced crack formation was greatest at the contact edge. The maximum tensile stress, maximum compressive stress, and maximum shear stress increase with contact load. The shear stress distribution is entirely confined within the coating and did not significantly affect the coating substrate.

High-Temperature Friction Behavior of Graphene Oxide/Magnesium Oxide Composites Modified by Silane Coupling Agent

High-Temperature Friction Behavior of Graphene Oxide/Magnesium Oxide Composites Modified by Silane Coupling Agent

Frictional and Particle Emission Behavior of Different Brake Disk Concepts Correlated with Optical Pin Surface Characterization

Brake wear emissions can be reduced by altering the surface of brake disks. A parametric study using a gray cast iron and a laser-cladded brake disk was performed in a pin-on-disk experiment with integrated optical pin surface characterization and particle emission measurement. Significant differences in the friction, wear and emission behavior are present. The high wear-resistance of the laser-cladded disk led to a reduction of 70% of the particle number emission relative to the gray cast iron disk, but the coefficient of friction was unstable. The surface of the pin used with the gray cast iron showed an initial large debris extension and protruding patches that were removed at high braking energies, exposing white patches and creating holes. These observations correspond to known processes from the plateau theory. The surface of the pin used with the laser-cladded disk showed a topography dominated by holes with almost no protruding patches. The braking condition did not influence the pin surface, implying that the disk and not solely the pin surface might be governing the friction process, and therefore challenging the applicability of the plateau theory to laser-cladded disks. To further study this aspect, a segmentation method was developed for the pin surface images and topographical data to extract and quantify different features on the pin, such as debris, patches, holes and the tribolayer. The correlation of the surface coverage ratios of the feature classes with the braking conditions (speed and applied pressure), the coefficient of friction and the emissions confirmed the differences between the gray cast iron and laser-cladded brake disk.

StiffGIPC: Advancing GPU IPC for Stiff Affine-Deformable Simulation

Incremental Potential Contact (IPC) is a widely used, robust, and accurate method for simulating complex frictional contact behaviors. However, achieving high efficiency remains a major challenge, particularly as material stiffness increases, which leads to slower Preconditioned Conjugate Gradient (PCG) convergence, even with the state-of-the-art preconditioners. In this paper, we propose a fully GPU-optimized IPC simulation framework capable of handling materials across a wide range of stiffnesses, delivering consistent high performance and scalability with up to 10 × speedup over state-of-the-art GPU IPC methods. Our framework introduces three key innovations: 1) A novel connectivity-enhanced Multilevel Additive Schwarz (MAS) preconditioner on the GPU, designed to efficiently capture both stiff and soft elastodynamics and improve PCG convergence at a reduced preconditioning cost. 2) A C 2 -continuous cubic energy with an analytic eigensystem for inexact strain limiting, enabling more parallel-friendly simulations of stiff membranes, such as cloth, without membrane locking. 3) For extremely stiff behaviors where elastic waves are barely visible, we employ affine body dynamics (ABD) with a hash-based two-level reduction strategy for fast Hessian assembly and efficient affine-deformable coupling. We conduct extensive performance analyses and benchmark studies to compare our framework against state-of-the-art methods and alternative design choices. Our system consistently delivers the fastest performance across soft, stiff, and hybrid simulation scenarios, even in cases with high resolution, large deformations, and high-speed impacts.

An Experimental Investigation of the Impact of Additive Concentration on the Tribological Performance of Castor Oil Lubrication in Piston Ring–Cylinder Liner Contact

This experimental study investigates the critical role and impact of additive concentration in enhancing the tribological performance of castor oil as a biolubricant for agricultural tractor engines. Friction and wear are major contributors to reduced engine efficiency, highlighting the need for effective lubrication strategies. While biolubricants like castor oil offer environmental benefits, they often require additives to achieve optimal performance. However, the concentration of these additives is crucial, as an imbalance can negatively impact the lubrication system, leading to a higher coefficient of friction, increased wear, and reduced engine efficiency and lifespan. This study examines the effects of varying concentrations of a mixture of propyl gallate (PG) and ionic liquid (IL) additives on the tribological performance of castor oil. The tribological behaviour of lubricated top compression piston ring and cylinder liner samples was evaluated under simulated engine conditions using a Bruker UMT Tribolab test rig, in accordance with the ASTM G181 standard. The experimental results revealed an influence of additive concentration on the coefficient of friction and wear behaviour. This emphasises the importance of optimising additive formulations to minimise engine wear and friction. Notably, a 0.5% volume concentration of the additive mixture led to a remarkable 34.8% reduction in the average coefficient of friction (COF) and a lower wear rate.

Seismic Fault Weakening Due To Thermal Pressurization of Comminution‐Induced Hydrophilic Talc

AbstractTalc is generally considered to be frictionally stable, yet the mechanochemical effect of extensive comminution along the fault gouge remains poorly understood. Here, we report that intact hydrophobic crystalline talc was mechanochemically changed into hydrophilic talc, by comminution using high‐energy ball milling. The weight fraction of water on the intact talc was close to zero, which gradually increased to approximately 0.13 with comminution. Then, we performed thermo‐mechanical‐chemical numerical modeling of thermal pressurization (TP) under seismic slip with parameterization of the water content of hydrophilic talc. In the comminuted hydrophilic talc model, the effective shear stress of the talc‐bearing fault patch converges to near zero, accompanied by pore pressure buildup due to seismic frictional heating and TP. Our results highlight that a fault containing the comminuted talc has the potential to exhibit slip‐weakening frictional behavior and catastrophic fault rupture, beyond the previous thought that the talc is frictionally stable with slip‐strengthening.

Tribological Performance of Electrochemically Textured EN-GJS 400-15 Spheroidal Cast Iron

This paper presents an experimental study of uniform and variable texture patterns on a honed EN-GJS 400-15 spheroidal graphite cast iron surface. Textured samples were fabricated using a CNC electrochemical jet machining technique and tested against a 52100 G5 roller countersurface featuring a rectangular 1 mm × 13 mm contact area. Tribological tests were conducted in a fully flooded PAO4 lubricant bath at 30 °C on a TE-77 reciprocating sliding tribometer with a 25 mm stroke length. Frictional behaviour was assessed at test frequencies from 12 to 18 Hz under two loads, 11 N and 50 N, covering mixed and hydrodynamic lubrication regimes. Experimental results demonstrated that EJM textured surfaces were accurately fabricated within a ±2.50 µm standard error in depth, with chemical etching effects reducing the Rq roughness of initial grinding marks by 0.223 µm. Textured surfaces exhibited a more pronounced friction performance at 50 N than at 11 N, exhibiting a consistent friction reduction of up to 18.8% compared to the untextured surface. The variable textured surface outperformed the uniform textured surface under the mixed lubrication regime due to the enhanced secondary lubrication effect. Optical and SEM analyses revealed that textured surfaces reduced plastic deformation and two-body abrasion.

Tribological performance of electric transmission fluid enhanced with silicon dioxide and graphene nanoparticles: Impact of concentration on wear reduction and frictional behavior

Tribological performance of electric transmission fluid enhanced with silicon dioxide and graphene nanoparticles: Impact of concentration on wear reduction and frictional behavior