Piston Rings Research Papers - Academia.edu (original) (raw)

2025, Sanjay

Internal combustion engines are intricate systems comprising numerous components that work together to generate power and maintain efficiency. Among these parts, the piston ring is a small yet critically important element often taken for... more

2025, Journal of KONES

The paper presents investigation of the influence of the friction force calculation method on the results of simulations run with the use of the model of gas flow from the combustion chamber to the crankcase and piston rings motion in the grooves. The first series of simulations was run using the gas flow and ring motion model in which the friction force was calculated from the empirical equation. The second series was run with the use of the gas flow and ring motion model fully integrated with the ring lubrication model. In that case the friction force was derived from the hydrodynamic model of ring lubrication. Comparison of the results obtained in the first and second series of simulations indicated that despite the fact that the friction forces calculated with these two methods differed considerably, the method of friction force calculation had insignificant effect. This refers to the quantities determined in the simulations which are most important from practical point of view ...

2025

The paper describes a method of experimental research of ringpack performance, which enables direct measurements of ring axial movements in the groove, pressures in inter-ring lands and temperatures of piston during actual engine operation. The research piston was equipped with a set of sensors and two electronic modules. The set of sensors consists of two piezoelectric pressure transducers, two proximity sensors based on Hall effect, two accelerometers and surface thermocouples. One of the electronic modules incorporates a microcontroller and signal conditioning circuits. The second module contains batteries and optical coupling for communication. Movable data acquisition system enables simultaneous measurement of data from eight channels with high resolution in domain of crankshaft angle. During measurements data is stored in external memory and afterwards can be retrieved and sent to personal computer. Result obtained with the use of developed wireless measurement and data acquisition system will be used in order to validate mathematical model of gas flow and piston rings dynamics.

2025

The article presents some aspects of developing, within INOE 2000-IHP, of an experimental research on the determination of frictional forces that occur in the mobile sealings of the pistons, between the piston sealings and the inner liner of hydraulic cylinders. In the first part of the paper, are presented some specific elements of the experimental device and of the testing stand which have been developed, while in the second part are presented some graphical results obtained in experimental research, as well as some comments on them. This developed experimental research marks the continuing of a major action on the tribological behavior of mobile hydraulic seals, which are frequently used in the construction of hydraulic cylinders. © 2014 Published by Faculty of Engineering Corresponding author: Corneliu Cristescu Hydraulics and Pneumatics Research Institute, Romania. E-mail: corneliu_cristescu@yahoo.com

2025, Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology

Power losses in high-speed gears come from the friction between the teeth (sliding and rolling), the lubrication process (dip or jet lubrication), the pumping of a gas-lubricant mixture during the meshing, and the losses associated with windage effects. The authors have developed different approaches to analyse the contribution of each power loss source, namely: (a) the windage losses based on simplified air flow models neglecting the influence of the lubricant, which compare well with the experimental evidence from a specific test bench; (b) an original model of gas trapping in the intertooth time-varying spaces, which has been validated using the experimental findings on a spur gear test rig in which pressure transducers have been placed at the bottom of the space between two teeth; (b) tooth friction, by introducing into a three-dimensional dynamic model of gears a new traction law based on measurements from a two-disc machine which accounts for lubricant properties and surface f...

2025, Lubricants

This paper presents an investigation of the frictional behaviour of three-piece piston oil control rings. A bespoke tribometer replicates the kinematics of the contact between a full oil control ring and the cylinder liner. The three-piece oil control ring is composed of two segments, separated by a waveform-type expander. The experimental results indicate the dominance of a mixed regime of lubrication throughout the stroke. This is particularly the case when the experiments are conducted at 80 • C, a typical engine sump temperature, when compared with those at 20 • C (a typical engine startup temperature in the UK in the summer). A mixed hydrodynamic analytical model of the oil control ring-cylinder liner tribological interface is employed to apportion frictional contributions with their physical underlying mechanisms. Therefore, combined numerical and experimental investigations are extended to lubricant contamination/dilution by ethanol-based fuels. This study shows that the transition from E10 to E85 would have an insignificant effect on the friction generated in the oil control ring conjunction. This holistic approach, using a detailed predictive l mixed regime of lubrication model and a representative bespoke tribometry, has not hitherto been reported in the open literature.

2025, Tribology International

Textured surfaces have been shown to provide enhanced tribological performance in a variety of contacts. Numerical analysis and optimisation methods are combined for application-oriented texture optimisation. However, an analytical approach is advantageous in providing more generic in-depth understanding of the nature of the relationships between texture parameters and objective functions, such as enhanced load carrying capacity and reduced friction. The paper outlines such an approach to obtain a set of global optimum design parameters for partially textured surfaces. The optimised results are expressed in dimensionless form, which enables their use for a variety of applications. The performance of optimised partially textured sliding surfaces is compared with the other conventional bearing geometries in their optimum state.

2025, Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science

The paper presents direct measurement of in-cylinder friction from a single cylinder motocross race engine under motored conditions and compares the same with a new analytical predictive method. These conditions are encountered in piston-cylinder system with the application of cylinder deactivation (CDA) technology, which is a growing trend. The analytical method takes into account the various regions within instantaneous contact of compression ring-cylinder liner, including lubricant film rupture, cavitation zone and the subsequent lubricant film reformation. The analysis also includes the effect of boundary friction and lubricant rheology. The predictions and direct measurements of cyclic friction show good agreement and indicate dominance of viscous friction under the investigated engine running conditions. In particular, it is shown that the compression ring contribution to in-cycle friction is most pronounced in the region of high cylinder pressures because of combined Poiseuille friction and some boundary solid interactions. The combined experimental-analytical approach has not hitherto been reported in literature.

2025

Abstract. Rolling bearings represent some of the most important uproar and vibration generators in mechanical structures. Accordingly, it is very important to know the impact of rolling bearing structure on the main parameters which determine the level of uproar and vibrations produced inside machines. This paper presents a mathematical model of the dynamic behavior of rigid rotor inside the rolling bearing and also a theoretical analysis of the rolling bearing structure with respect to the frequency of calibrated rigid rotor oscillation inside the rolling bearing.

2024, Journal of scientific and industrial research

This study presents performance behaviors of a commercial diesel engine fueled with diesel and Jatropha based biodiesel (B100) at various loads (up to 100%) using standard (conventional) and three new face profile designs (I, II & III) of piston rings. Face profiles of piston rings had considerable impact on engine's brake thermal efficiency (BTE), brake specific fuel consumption (BSFC), and mass flow rate, irrespective of fuels used. BTE of engine fueled with diesel increases 2-8% with new face profile design (III) of piston rings in comparison to standard (conventional) piston rings. BTE enhances 8-16% when engine is fueled with biodiesel using face profile design (III) on piston rings. Corresponding to increase in BTE, recorded reduction in BSFC (biodiesel) is 28-34%. Industrial application of the results of present study may be useful in saving of fuels.

2024, Silniki Spalinowe

The paper presents a mathematical model of ring pack of a diesel engine. A submodel of ring twists is described in details. Numerical algorithms applied and computer program worked out are characterised. A method of input data determination and results of simulations are also described. The results of initial simulations investigating the effect of engine operation condition on ring twists are pesented. The possible applications of the results of calculations in engine design is also discussed in the paper.

2024

For different operating conditions of an internal combustion engine, the piston-ring-liner compartment represents one of the largest sources of friction and power losses. The present paper is a contribution to evaluate the effect of the compression ring profile on the main tribological performance of the lubricant in a four-stroke diesel engine. A one-dimensional analysis was developed using GT-Suite software for the hydrodynamic lubrication between the compression piston ring and the cylinder wall. A numerical method was applied to analyze the influence of different ring geometrical designs during the working cycle on oil film thickness, frictional force, power losses. The Takigushi simulation model was used to validate and verify the developed numerical model. The results obtained showed a relatively good qualitative and quantitative compatibility between the two applied models. The developed numerical model allows the investigation of the influence of ring design parameters to im...

2024

For different operating conditions of an internal combustion engine, the piston-ring-liner compartment represents one of the largest sources of friction and power losses. The present paper is a contribution to evaluate the effect of the compression ring profile on the main tribological performance of the lubricant in a four-stroke diesel engine by using the GT-suite simulation software. A one-dimensional analysis is developed for the hydrodynamic lubrication between the compression piston ring and the cylinder wall. A numerical method is applied to analyse the influence of different ring geometrical designs during the working cycle on oil film thickness, frictional force, power losses. The Takiguchi simulation model /1/ is used to validate and verify the developed numerical model. The results obtained show a relatively good qualitative and quantitative compatibility between the two applied models. The developed numerical model allows the investigation of the influence of ring design...

2024, Proceedings of the World …

 Abstract. The piston top ring in an automotive ring-piston system plays a very crucial role during the engine start up and normal operating conditions. A hydrodynamic piston top ring lubrication model in the initial engine start up is... more

2024, Tribology International

Prediction of load capacity and friction depends on the assumed boundary conditions. The inlet comprises swirl and counter flows, admitting only a portion of the inward flow into the conjunctional gap. At the contact exit, the lubricant film ruptures with multi-phase flow through a cavitation region. Therefore, the boundary conditions affect the load carrying capacity and friction. A Navier-Stokes solution of multi-phase flow, including vapour transport is presented, with determined realistic boundary conditions. The evaluated boundaries agree with potential flow analysis satisfying compatibility conditions, not hitherto reported in literature. The investigation is extended to the determination of optimum compression ring contacting geometry.

2024

This paper investigates the structure analysis of cast iron for dry clutch disc of amphibious vehicle. The main focus that needs to be considered is the torque produced from the engine. Optimum parameters must be justified in order to confirm the clutch disc is high durability, high reliability, and minimum in weight. Finite element analysis is use to predict the maximum stress can be apply to the disc. The fabrication process is conduct using a conventional milling machine.

2024

In this work, a three-dimensional dynamic simulation model for cylindrical roller bearings is developed based on multi-body-simulation software SIMPACK and programming language FORTRAN. The aim of this work is to build a universal program to calculate the dynamic behavior of cylindrical roller bearings. This simulation model integrates major part of the functionalities according to the state of the art of existing programs which are: the slice model, the mutual influences of neighboring slices, the basic three-dimensional model, the calculation of lubricant film thickness and damping forces, the radial clearance, the roller-pocket clearance, the centrifugal forces and the hysteresis damping forces. The extended functionalities in this work can be summarized as follows: 1) Roller-pocket contact stiffness is taken into account and calculated with the help of finite element analysis. 2) The three types of cage guidance are modeled in details which are roller guidance, inner ring guidan...

2024

This paper describes the stress distribution and thermal stresses of three different aluminium alloys piston by using finite element method (FEM). The parameters used for the simulation are operating gas pressure, temperature and material properties of piston. The specifications used for the study of these pistons belong to four stroke single cylinder engine of Hero Spledor motorcycle. This paper illustrates the procedure for analytical design of pistons using specifications of four stroke single cylinder engine of Hero Spledor motorcycle. The results predict the maximum stress and critical region on the different aluminium alloy pistons using FEA. It is important to locate the critical area of concentrated stress for appropriate Modifications. Static and thermal stress analysis is performed by using HYPER WORKS 13.0. The best aluminium alloy Material is selected based on stress analysis results. The analysis results are used to optimize piston geometry of best aluminium alloy.

2024, Journal of Computational and Theoretical Nanoscience

The wide use of textured surfaces in lubrication to improve lubrication and tribological characteristics has been remarked recently. The understanding of the textured surface geometric parameters influences on these characteristics could help to improve their applications in industry. This paper presents analyzes the influences of the flow speed and the texture deepness on the lubrication hydrodynamic characteristics (shear stress and friction coefficient). Considering that the loads are only exerted by the fluid on the faces of texture (no external force applied), a theoretical relation has been established between the texture deepness and the shear stress. The numerical simulation, using the software "Solidworks flow simulation," has been also driven, on a Wenzel model of micro-asperity, with the conditions of no-slip at the upper surface and slip on the micro-asperities faces. The shear stress, friction coefficient and pressure have been plotted using different values of speed and texture deepness and then analyzed. A significant reduction of friction coefficient with the increase of speed and also with the increase of deepness has been observed.

2024

rior (CAPES) (grant PROEX-8434433/ D) for funding my research during my PhD and internship abroad (grant 88881.133497/2016-01). I also want to thank to all professors and faculty members from ICMS-USP who, directly or indirectly... more

2024

This research aims to examine the compound impact of adding rectangular textures to various zones on the surface of the bearing and nanoparticles in the lubricant on the properties of journal bearing. A lubrication models with various texture depths and eccentricity ratios of journal bearing are created and simulated using CFD-FSI method to get static properties like load capacity and frictional force. Aluminum oxide nanoparticles were added in weight ratios ranging from 0.1 to 0.5 %, and the change in viscosity due to these additives in the lubricant was considered. Cavitation and the dependence of viscosity on temperature effects are also considered. The validation results show that the acquired results from the current simulation method agree well with the experimental results in the reference. The outcomes indicated that the highest load capacity and the lowest frictional force are found in the high-pressure region. It was noted that the maximum rise in load capacity was 16.51% without nanoparticles at a texture depth of 0.5 mm and eccentricity ratio of 0.1, and with the adding of 0.5 wt. % of nanoparticles to the lubricant in the same region, the load carrying capacity increased to 40.87 % compared to a bearing without textures.

2024

In IC engine piston ring friction losses account for approximately 20% of total mechanical losses. A reduction in piston ring friction would ergo result in higher efficiency, lower fuel consumption and reduced emissions. To reduce these losses, sundry parametric approaches are made concretely at design stage and experimental level. The goal of this study was develop piston ring designs to amend engine efficiency, without adversely affecting oil consumption, blow by, wear and cost. Thus it provides characterization of a pressure balance in terms of efficacious area and distortion coefficient of the piston and cylinder. The variable parameters are piston velocity, engine haste, oil viscosity, gas pressure, crank angle film thickness and coefficient of friction. Non variable parameter are system constant, bore diameter, ring tension, ring width, compression ratio, reciprocating mass, piston ring area and piston ring profile. The major posits for developing models are either hydrodynami...

2024, Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology

The paper presents transient thermal-mixed-hydrodynamics of piston compression ring-cylinder liner conjunction for a 4-cylinder 4-stroke gasoline engine during a part of the New European Drive Cycle (NEDC). Analyses are carried out with and without cylinder de-activation technology in order to investigate its effect upon the generated tribological conditions. In particular, the effect of cylinder deactivation upon frictional power loss is studied. The predictions show that overall power losses in the piston-ring cylinder system worsen by as much as 10% because of the increased combustion pressures and liner temperatures in the active cylinders of an engine operating under cylinder deactivation. This finding shows the down-side of this progressively employed technology, which otherwise is effective in terms of combustion efficiency with additional benefits for operation of catalytic converters. The expounded approach has not hitherto been reported in literature.

2024, Surface topography

The paper presents a combined numerical and experimental study of generated sliding friction at low sliding speeds and high load intensity, typical of the top compression ring-cylinder liner conjunction at top dead centre in the compression stroke of high performance race engines. Frictional losses in the transition from compression to power stroke represent a significant portion of cyclic cylinder losses. The cylinder liner is cross-hatch honed with non-Gaussian topography, including larger groove features and a fairly smooth plateau roughness. Surface-specific flow factors are derived to closely represent the actual real rough conjunction. The predictions closely agree with the representative reported precision tribometric study of measured friction.

2024, Proceedings Of The Institution Of Mechanical Engineers, Part K: Journal Of Multi-body Dynamics

The piston compression ring's primary function is to seal the combustion chamber, thus mitigating gas leakage to the crankcase and avoiding loss of pressure loading. As a result, the ring is meant to conform closely to the cylinder surface which promotes increased friction. The compression ring is subjected to combustion pressure loading, ring tension, varying inertial force and friction. It is a slender ring of low mass, thus undergoes complex elastodynamic behaviour, when subjected to a multitude of forces. These motions occur in the ring's radial in-plane and axial out-of-plane dynamics, which comprise flutter, ring axial jump, compression-extension, ring twist and rotational drag. An implication of these motions can be loss of sealing, gas blow-by, loss of power and lubricant degradation/oil loss, to name but a few. Consequently, understanding and accurately predicting ring dynamic behaviour under transient conditions is an important step in any subsequent modelling for evaluation of cylinder system efficiency. There have been a plethora of investigations for ring dynamics, often decoupling the ring behaviour in its in-plane and out-of-plane motions. This approach disregards any transfer of dynamic energy from one degree of freedom to another which is only applicable to rectangular ring cross-sections. Alternatively, there are computationally intensive approaches such as finite element analysis which are not conducive for inclusion in any subsequent system level engine modelling where ring response alters in an instantaneous manner. This would require embedded finite element analysis within a transient analysis. This paper presents a finite difference numerical analysis for coupled in-plane and out-of-plane motions of compression rings with practical cross-sectional geometries, which are mostly not rectangular. The formulated method can be integrated into a system level transient cyclic analysis of ring-bore contact. The presented approach takes into account the energy transfer between different degrees of freedom. The predictions are validated against precise non-contact measurements of ring elastodynamic behaviour under amplitude-frequency sweeps. This approach has not hitherto been reported in literature and constitutes the main contribution of the paper.

2024, Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology

Reciprocating and low-speed sliding contacts can experience increased friction because of solid boundary interactions. Use of surface texturing has been shown to mitigate undue boundary friction and improve energy efficiency. A combined numerical and experimental investigation is presented to ascertain the beneficial effect of pressure perturbation caused by micro-hydrodynamics of entrapped reservoirs of lubricant in cavities of textured forms as well as improved microwedge flow. The results show good agreement between numerical predictions and experimental measurements using a precision sliding rig with a floating bed-plate. Results show that the texture pattern and distribution can be optimised for given conditions, dependent on the intended application under laboratory conditions. The translation of the same into practical in-field applications must be carried out in conjunction with the cost of fabrication and perceived economic gain. This means that near optimal conditions may suffice for most application areas and in practice lesser benefits may accrue than that obtained under ideal laboratory conditions.

2024

This paper investigates the influence of shaft surface topography upon seal leakage, when using different surface finishing and manufacturing techniques. A hydrodynamic model is used to determine the generated pressure distribution within the seal-shaft contact. Pertinent statistical parameters are selected to distinguish between the various shaft surface topographies, which can contribute to an effectively sealed conjunction. Results obtained from the hydrodynamic model shows the creation of multiple cavitated regions caused by the deep valleys. This leads to thinner film thickness on the surface plateau and therefore lower predicted leakage rates. The distribution of peaks and valleys is shown to be a factor in differentiating contact performance.

2024, PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON RECENT ADVANCES IN MANUFACTURING ENGINEERING RESEARCH 2021: ICRAMER 2021

Piston rings are one of the most important sub-components of the IC engine. Cast Iron and Steels are among the materials used to manufacture Piston Rings. The common wear factors of a Piston Ring are friction, corrosion and thermal loads. Many researchers have come up with various effective methods such as improved Lubrication methods and Coatings to significantly reduce the wear factors improving the life and efficiency of the Piston rings. Existing coating technologies include plasma spraying, gas nitriding, chromium plating, physical vapor deposition which provide improved wear resistance. The sustained improvement of engine performance has compelled the engineers to develop piston rings of significantly greater efficiency. This induces various stresses in the moving assemblies such as adverse mechanical and thermal load specifically on the engine piston assembly. This research deals with study of different aspects of stress under the real conditions of loading such as mechanical stresses and wear, which will improve engine efficiency and effectively control oil lubrication. Chromium plating is one of the earliest coatings which is cost effective but requires improvements to cater to increasing demands. This paper deals with the testing of different chrome coatings on piston rings. The materials are Normal Chrome Coating, Moly Ceramic Chrome (MCC) and MC coated piston rings. The wear resistance tests conducted on Linear Reciprocating wear test tribometer produced valuable outputs. The tribometer works on the principle of pressing the test specimen on a cylinder liner in a reciprocating fashion simulating the action of an IC engine. The test was conducted in lubricated conditions with constant load of 50N and frequency 5Hz at 100֯ C for a time period of 60 minutes. The post wear tests including weight loss and contour analysis on worn out rings was performed.

2024, Journal of KONES. Powertrain and Transport

Assumptions made while modelling the oil film between the ring and the cylinder liner in IC engines, especially concerning the boundaries of the wetted area of the ring face surface, were discussed and the assumptions adopted for the developed model were presented in this study. It was assumed that the model should take into account partially flooded lubrication, which meant that the boundaries of the ring wetted area had to be determined. Based on the adopted assumptions, a model for calculation of the oil film thickness between the cylinder and moving rings, and thickness of the oil film left on the cylinder by the ring pack was developed. A computer application operating in the Windows operation system was developed to carry out numerical calculations. The results of initial numerical calculations were also presented. The proposed model can be utilized to determine the effects of the ring pack geometry, especially the geometry of the ring surface, on parameters of lubrication. These parameters, including the oil film thickness, distribution of pressure in oil film or tangential force, are crucial for friction and wear of cooperating surfaces, oil consumption, and flow of gas from the combustion chamber to the crankcase, thus playing a role in the durability, fuel consumption and emission of an engine.

2024, Lubricants

This paper presents an investigation of the frictional behaviour of three-piece piston oil control rings. A bespoke tribometer replicates the kinematics of the contact between a full oil control ring and the cylinder liner. The three-piece oil control ring is composed of two segments, separated by a waveform-type expander. The experimental results indicate the dominance of a mixed regime of lubrication throughout the stroke. This is particularly the case when the experiments are conducted at 80 ◦C, a typical engine sump temperature, when compared with those at 20 ◦C (a typical engine startup temperature in the UK in the summer). A mixed hydrodynamic analytical model of the oil control ring–cylinder liner tribological interface is employed to apportion frictional contributions with
their physical underlying mechanisms. Therefore, combined numerical and experimental investigations are extended to lubricant contamination/dilution by ethanol-based fuels. This study shows that the transition from E10 to E85 would have an insignificant effect on the friction generated in the oil control ring conjunction. This holistic approach, using a detailed predictive l mixed regime of lubrication model and a representative bespoke tribometry, has not hitherto been reported in the open literature.

2024, Revista de Metalurgia

El comportamiento del revestimiento del anillo del pistón de combustión representa una de las mayores fuentes de fricción y de potencia para diferentes condiciones de funcionamiento de un motor de combustión interna. El presente trabajo evalúa el efecto del perfil del anillo de compresión sobre el principal comportamiento tribológico del lubricante en un motor diésel de cuatro tiempos. Se desarrolló un análisis unidimensional utilizando el software GT-Suite para la lubricación hidrodinámica entre el segmento del pistón de compresión y la pared del cilindro. Se aplicó un método numérico para analizar la influencia de los diferentes diseños geométricos de anillos durante el ciclo de trabajo sobre el espesor de la película de aceite, la fuerza de fricción y la pérdida de potencia. Se utilizó el modelo de simulación de Takigushi para validar y verificar el modelo numérico utilizado. Los resultados obtenidos mostraron una compatibilidad cualitativa y cuantitativa buena entre los dos mode...

2024

For different operating conditions of an internal combustion engine, the piston-ring-liner compartment represents one of the largest sources of friction and power losses. The present paper is a contribution to evaluate the effect of the compression ring profile on the main tribological performance of the lubricant in a four-stroke diesel engine by using the GT-suite simulation software. A one-dimensional analysis is developed for the hydrodynamic lubrication between the compression piston ring and the cylinder wall. A numerical method is applied to analyse the influence of different ring geometrical designs during the working cycle on oil film thickness, frictional force, power losses. The Takiguchi simulation model /1/ is used to validate and verify the developed numerical model. The results obtained show a relatively good qualitative and quantitative compatibility between the two applied models. The developed numerical model allows the investigation of the influence of ring design...

2024, Wear

Over the years, investigators have extensively studied various aspects of wear in cylinder liners but a survey of the literature has revealed little information on the subject of high wear rates found in the upper portion of the liners. In order to provide a better understanding of the subject, an attempt is made in this paper to assess the primary factors responsible for the high wear rates. It is observed that, although several factors can operate at the same time in influencing the wear process, in general wear is controlled by adhesion with contributions later on from corrosive and abrasive processes. The metallurgy of the liner also plays an important role in determining wear rates.

2024, Coatings

The objective of this paper is to highlight the need to combine lifecycle environmental assessment with durability evaluation (tribology and engine tests) to evaluate the potential of surface technologies to contribute to the green deal, in order to make Europe the first climate-neutral continent. Tribology is a scientific discipline that allows one to understand the system reaction to friction and wear. Tribological testing machines are prepared to measure friction at the laboratory level to minimize the wear and heat dissipation of two bodies in relative movement, thus improving the energy efficiency and minimizing CO2 emissions. In this paper, different surface technologies, such as high-velocity oxyfuel (HVOF), physical vapor deposition (PVD), and clean Cr electrolytic processes, are analyzed as promising surface technology solutions from both performance and environmental impact perspectives to replace harmful Cr(VI) coatings. The tribology simulates the working conditions of t...

2024, Lubricants

The objective of the present investigation is to analyze the tribological performance between the union of the cylinder liner and the compression ring under the influence of surface texturing and different lubrication boundary conditions. The analysis is carried out by developing a numerical model, which involves hydrodynamic pressure, lubrication film thickness, textured surface, dynamic forces, and lubrication boundary conditions (starved lubrication and fully flooded lubrication). MATLAB® software (The MathWorks Inc., Natick, MA, USA) is used to solve the equations developed. The results show that the application of a textured surface on the cylinder liner allows obtaining a reduction of 20% and 5% in the asperity contact force and in the total friction force. Additionally, the textured surface allows for a 4% increase in MOFT. In this way, it is possible to reduce the power loss. The implementation of a boundary condition of fully flooded lubrication produces an overestimation i...

2024, Lubricants

The contact between the piston rings and the cylinder liner is an interface with a strong influence on the tribological behavior and, therefore, directly affects the useful life of the engine components and fuel consumption. Due to this importance, the present investigation carried out an analysis of the effects of dimples and the honing groove in the cylinder liner on the tribological characteristics. A tribological model was developed to study the friction forces, minimum film thickness, and friction coefficient for the present investigation. Similarly, a computational fluid dynamics model was built to determine the dynamic movement of the piston. The validation of the numerical model showed a close similarity with the real behavior of the engine, obtaining an average relative error of 14%. The analysis of the results showed that a 3% increase in dimples’ density leads to a 3.79% increase in the minimum lubricant film and a 2.76% decrease in friction force. Additionally, it was sh...

2024

the 1 st compression ring adversely in the absence of a fully developed elastohydrodynamic lubricating (EHL) film. The adverse effects may allow a physical contact and wear of the ring and the liner surfaces. This study develops the numerical models of the hydrodynamic and EHL of the 1 st compression ring at a very low initial engine start up speed. Then the results are compared with those at the other two low speeds, considered separately. The secondary dynamics of the piston ring assembly and the barrel-face profile of the ring are incorporated in the models. The Reynolds equation is solved to generate the hydrodynamic pressures, developed over the circumferential length of the ring. The inverse solution technique is employed to study the rising EHL pressures and the EHL film profiles after incorporating the elastic surface displacements in the models. The simulation results show the hydrodynamic and EHL film thicknesses as the function of the 720 - degree crank rotation cycle. Th...

2024, arXiv (Cornell University)

Laser Texturing is one of the leading technologies applied to modify surface topography. To date, however, a standardized procedure to generate deterministic textures is virtually nonexistent. In nature, especially in squamata, there are many examples of deterministic structured textures that allow species to control friction and condition their tribological response for efficient function. In this work, we draw a comparison between industrial surfaces and reptilian surfaces. We chose the python regius species as a bio-analogue with a deterministic surface. We first study the structural make up of the ventral scales of the snake (both construction and metrology). We further compare the metrological features of the ventral scales to experimentally recommended performance indicators of industrial surfaces extracted from open literature. The results indicate the feasibility of engineering a Laser Textured Surface based on the reptilian ornamentation constructs. It is shown that the metrological features, key to efficient function of a rubbing deterministic surface, are already optimized in the reptile.

2024, Surface topography

2024, Advances in intelligent systems research

Contact force distribution analysis is the foundation of the load-carrying capacity analysis, the drawing of static load-carrying capacity curve, designing and selecting of slewing bearings. The static model of the single-row four point contact ball slewing bearing is established and the contact force distributions are solved under different types of load. The characteristics of contact force distribution of this bearing are analyzed and the influence of bearing parameters on contact force distribution is analyzed. Results show that the characteristics of contact force distributions on raceway are different under different types of load. With the increase in the contact angle and the decrease in the groove curvature radius coefficient, the loads on raceway decrease and the load-carrying capacity of bearing increases.

2024, Proceedings Of The Institution Of Mechanical Engineers, Part K: Journal Of Multi-body Dynamics

The amount of vibration induced by surface waviness in a touchdown bearing can be modelled with a multibody approach. This study develops a multibody model that accounts for surface waviness in races of touchdown bearings and employs the model to define the dissimilarities of the rotor and inner ring movements, and to perform inner ring velocity analysis in the frequency domain. Model results are compared with measured and simulated outcomes in the literature. Large movements are found in the orbits and velocities in the frequency domain due to surface waviness. Inner race eccentricity and ellipticity seem to be the cause of the most damaging surface waviness. In the frequency domain, all the significant peaks were noticed to be multiplications of rotor pendulum frequency, and the frequency of the inner ring was traceable in cases with waviness in the bearing. The model proposed in this study enables waviness to be taken into account in design of touchdown bearings.

2024, Journal of Mechanical Engineering and Sciences

Fundamental understanding of piston ring-pack lubrication is essential in reducing engine friction. This is because a substantial portion of engine frictional losses come from piston-ring assembly. Hence, this study investigates the tribological impact of different piston ring profiles towards engine in-cylinder friction. Mathematical models are derived from Reynolds equation by using Reynolds’ boundary conditions to generate the contact pressure distribution along the complete piston ring-pack/liner conjunction. The predicted minimum film thickness is then used to predict the friction generated between the piston ring-pack and the engine cylinder liner. The engine in-cylinder friction is predicted using Greenwood and Williamson’s rough surface contact model. The model considers both the boundary friction and the viscous friction components. These mathematical models are integrated to simulate the total engine in-cylinder friction originating from the studied piston ring-pack for a ...

2024, Tribology International

In this work we assess the applicability of the adjoint optimization technique for determining optimal surface topographies of two surfaces in relative motion in presence of a thin lubricant films that can cavitate. Among the existing numerical tools for topology optimization in engineering problems, the adjoint method represents a promising and versatile technique, which can also be applied to the field of full film tribology. In particular, the design of surfaces with complex textures can thoroughly benefit from this method, as it allows dealing with a large number of degrees of freedom at low computational cost. We show that this optimization method can be successfully applied to cavitating lubricant flows such as in pin-on-disc tribometers, giving the possibility to extend the results also to other typical applications such as journal and slider bearings. It is shown that the adjoint method can optimize the whole gap height distribution point by point in a more efficient way than traditional optimization approaches and parametric studies. In particular, thanks to the sensitivity analysis the adjoint method is able to find the placement and depth profile of each texture element.

2024

Although several methods have been already developed for solving thermo elasto-hydrodynamic (TEHD) problems, the solution of the highly nonlinear problem is still quite challenging. So the development of a P-version FEM model for calculating the film shape, the pressure and temperature distribution and its implementation to commercial software seems to be timely to study the slidingrolling materials during operation. Since the general 3D flow problem can be reduced to a quasi 2D case based on the hydrodynamic lubrication theory developed by Reynolds, special lubricant film element can be developed for finite-element modelling of such problems.

2024, International Journal of Mechanical Engineering and Robotics Research

The primary purpose of this work is to investigate the effect of the piston crown and piston boss thicknesses on the stresses generated on the piston. A 150-cc piston, made from A4032 Aluminum, of type "Bajaj," was considered in the present investigation. The piston head was subjected to a double-action of gas pressure and heat from the combustion process. Piston pin bore was considered to act as cylindrical support. ANSYS 15 was used to run the simulation process using the thermal structural couple technique. Different thicknesses of the piston crown and piston boss were selected and studied. The comparison and optimization processes depended on the Von-Mises stress, mass, and temperature distribution in the piston. Based on the stress values obtained for different piston sizes, the results clearly showed that the optimal piston design was 3 mm piston crown and 2 mm piston boss thicknesses. The optimal piston design reduced the total stress and mass, but it increased the temperature generated in the piston.

2024, IOP conference series

This paper presents an analysis of a nonlinear model of a rolling bearing with two degrees of freedom. The acceleration response provides information regarding the relationship between vibration and a different number of balls, values of internal clearance and rotary shaft speeds. The acceleration response is higher when the radial internal clearance and the shaft speed increase. When the number of balls increases, the acceleration decreases for the entire range of radial internal clearance. These results are useful for understanding the vibration response mechanism of ball bearings under variable parameters.

2024, Lubricants

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