Advances in Engine Tribology

Customers demands and stringent emission norms have compelled automotive manufacturers to deliver energy-efficient, economically viable, and environmentally friendly engines. The expectations are getting steeper with time. Advanced combustion systems and modified engine dynamics have given rise to scope for interdisciplinary research, including engine tribology aspects. Tribology has a key role in developing newer materials (ceramics, steels, coatings, lubricants, additives) to be applied along with novel fuels, low viscosity, green lubricants, and low heat rejection engines. This book has four sections: Introduction to advances in Engine tribology, Emerging challenges with modern engines, Recent advances in engine tribology, and Novel materials for advanced engine design. The first section is about the advances in tribology of the modern automotive sector. The second section of this book focuses on the emerging challenges in engine tribology related to friction, wear, and lubrication. The third section of this book deals with the development of next-generation materials and lubricating agents. Several studies on the application of composite materials, nanomaterial technology, are studied in the fourth section of this book. Systems like transmission, axle, tribo-corrosion, etc., which indirectly influence engine operation, have been reviewed from tribological aspects. Overall, this book covers all the aspects of tribological studies related to modern engines.

There is a significant demand for biofuels as an alternative fuel for existing internal combustion (IC) engines. The long-term effect of these fuels on engine hardware needs to be studied. These studies include friction, wear, and lubrication (tribology) of different engine parts. Tribological studies of bio-fuelled IC engines play a crucial role in scrutinizing legislated particulate matter (PM) emission norms. Wear of the mating interfaces of fuel injection systems and lubricating oils are an originator of PM emissions from the engine exhaust. The application of biofuels in the short term is encouraging. In long-term applications, durability tests resulted in problems with engine failure because of higher carbon deposition and lubricating oil degradation. This review chapter includes a detailed analysis of friction, wear, and lubrication characteristics of bio-fuelled compression ignition and spark ignition engines. The lubricating oils, their properties, and various additives used were assessed for the alcohol-fuelled engines. However, this review does not have any new results, and it highlights the previous studies and projects the future potential of tribology for bio-fuelled IC engines.

Biodiesel has been investigated in combustion engines for a long time. Numerous studies have been reported on the properties, performance, combustion, and emission analyses of biodiesel and their blended fuels. Mostly, researchers suggested promising blends based on the performance parameters. However, sometimes biodiesel-blended fuel affects the life of engine parts in the long term and leads to the wear of vital moving engine components. There are some studies, which have been focused on this aspect. The present study reviews the effects of biodiesel-blended fuels in the long term. The impact of blended fuels on vital engine parts like piston, piston rings, fuel injector, cylinder liner, and cylinder head in terms of carbon deposition and wear is discussed. The effects of modifications in engine parameters like compression ratio, injection timing, and injection pressure on carbon deposits and wear of the vital parts of the engine are also discussed.

It is very common to witness wear during the operation of SI components. Due to the thin oil film thickness present between the contacting mediums, it encounters serious wear problems in sliding components. Engine performance has greatly improved due to the development of ultralow viscous lubricating oils, however, engine wear has also increased. Wear is always challenging and its measurement is also difficult. In some studies, concern is expressed regarding the quantitative measurement of wear parts of machine equipment. It is, however, difficult to collect the data related to quantitative wear measurement. In recent years, attempts have been made to extend the life of such components by altering the mechanical strength of the materials used for those purposes. The purpose of this paper is to review on ways to improve the wear parts in SI engine.

A rail wheel and axle is an integrated and essential part of a wheel-set that provides a better and safe operation of rail vehicles. It supports the overall weight of the wagon. It cannot be designed as a safe structure from failure as it has forces acting in many directions. Hence, it requires high reliability in terms of power/torque and different types of strength. Necessary attention on the wear resistance, thermal crack resistance, noise/vibration, and the characteristics and performance of the wagon are required. Maintenance plays a vital role in increasing the life of the wheel and axles. Hence, more suitable wheels and axle production strategies should be started at the earliest to resolve wear issues. Indian railway is working on the Atma Nirbhar Bharat scheme, where the production of these wheels and axles will be implemented in the coming years. This research is about the efforts made by the Indian Railways to indigenize wheels and axle production with minimum wear.

Nanolubricants immersed in a liquid medium can be vital for interacting surfaces to compensate driving forces for low friction and wear properties. These two properties are essential for transportation vehicles because their components continuously interact with another part of the vehicle, which causes material wear. Hence, a lubricant film is required to protect these surfaces. If the lubricant film thickness drops or becomes too small to provide full fluid separation of the two interacting surfaces, rough surface asperities start to contact one another. Asperities are initially coated with a film of oxide, such as iron oxide on iron or steel, aluminum oxide on aluminum. As surface asperities rub against each other, there develops a tendency of adhesion. As rubbing continues, the oxide film is removed from the surface, which in turn causes high friction and severe wear. Boundary lubrication occurs when the lubricating film thickness equalizes with a thickness of surface roughness, leading to pure asperities contact between the surfaces. The work delivers recent developments in lubrication concepts and those essential for nanolubrication properties. It intends to support surface properties at nano/micro scales for various nanometric scale thick lubrication film design. Different nanoparticle friction behavior is studied in water/oil medium as nanosuspensions and as an additive with grease matrix with a pin-on-disc (POD) tribometer. The particle suspension and its dispersion were used to control by the surfactants/dispersants. The friction data of suspensions indicated that the particle size is an essential parameter in controlling the friction and wear.

This work presents detail about lubrication, different types of lubrication, tribological properties such as friction and wear, the composition of lubricants, and the impact of lubricants on the environment. Further, it covers types of the lubrication system, choice of lubricants, properties, and applications of nano particles-based lubrication in oil mediums. It also explains the properties of grease and its suitable applications, particle-based lubrication such as graphene, molybdenum disulfide, boron nitride, boric acid, tungsten disulfide. Nanocomposite-based lubrication properties of epoxy-graphene-molybdenum disulfide (MoS₂) under dry sliding contact are discussed in detail. Oil properties and their use, different oils, their viscosity, influencing parameters affecting the oil viscosity, viscosity and temperature relationship, methods to measure viscosity, and basics of absolute and kinematic viscosity are discussed. Significant rail components such as Elastic Rail Clips (ERC), Sealing linear, Switch Expansion Joint (SEJ) for effective lubrication methods are presented.

This paper presents in-depth review on the influence of friction, noise, vibration and acoustical behavior and their relationship with different approaches in past. The interdependencies and effect of friction induced noise, vibration and acoustical behavior are analyzed on the rough surface at different asperitical level. The origination of frictional (noise, vibration, acoustical behavior), its dependencies on rough surface under different wear conditions are critically reviewed. The review concludes that an analytical and computational modelling approach is necessary to study the effect of friction induced noise, vibration and acoustical behavior on the rough surface.

Composites form a modern class of structural materials that are increasingly replacing the conventional materials in various engineering domains due to the reduced density along with simultaneous enhancement in mechanical and tribological performance. Specific to the combustion engine application, usage of lighter materials becomes imperative as it yields greater fuel efficiency, bringing down the pollution related problems and leading to cleaner energy. Metal-based composite materials are found to be a potential solution to such problem owing to its higher strength to weight ratio achieved by tailoring the reinforcement-matrix composition and distribution. This chapter attempts to highlight the fundamental aspects of these composite materials and their performance against the conventional metallic class of materials along with the recent development in advanced composite materials. To rightly align with the central theme of this book, this chapter mainly focus on the role of composite materials on the improvement in tribological performance of automobile and aerospace engines. Special attention is given to the advanced composite materials that are of current research focus for improved tribological and high temperature performance in aerospace engine applications. A complete survey on the available work in this direction is being presented along with the challenges and future prospect.

In the 21stcentury, researchers have turned their attention towards composite materials (CMs) concerning lightweight applications in the automobile sector. Researchers have found a way to achieve better fuel efficiency by substituting conventional materials with novel variants. The history and state-of-the-art applications of composite materials in the automotive sector are presented. Material characteristics required for the substitution of composite materials over traditional automobile components are also discussed. The application of novel composite variants for automobiles offers significant advancements in material properties in terms of lightweight, cost, sustainability, and crashworthiness. Weight reduction in an automobile component exhibited by composite materials increased the fuel efficiency with reduced automobile emission. In addition, composite materials offered safety and comfort with improved vehicle performance due to the superior mechanical properties over conventional materials. Bio-composites comprised of natural material in metals and polymers have revealed a positive impact on environmental friendliness retaining its exceptional material properties for desired automotive application.

This control strategy can be quite handful in practical situations where constant rpm is the primary need, especially in case of heavy drilling machines/automobiles being employed in drilling large stone quarry in mines. In such a situation, the drilling needs to be performed at a predetermined speed only and major fluctuations in the speed can lead to undesirable results. To realize the same control strategy in real terms, the physical model of a closed loop HST (Hydrostatic Transmission system) system consisting of a variable displacement pump and a fixed displacement motor has been developed. Conventionally, the rpm of the motor decrease upon loading the pump as load pressure increases. This can severely affect the performance of the overall system as it is assumed that the system works excellently or is designed for certain range of rpm which should be more or less constant. Hence in view of the situation, a feedback control mechanism is applied via means of PID (Proportional, Integral and Derivative) controller which keeps track of the decline in rpm of the motor and through certain control strategy sends a command signal to the pump. Based on the received feedback signal, the inclination of the swash plate of the pump is varied resulting in the increase of the flow rate from the pump which consequently increments the rpm of the motor to match the demand requirements resulting in the constant rpm. Furthermore, an advanced PID controller constructed on the basis of neural network following has the capability of approximating nonlinearities. The devised controller has been found to be quite effective during simulations and has edge in regulating the parameters, better robustness and minimizing nonlinearities, fluctuations and errors. Performance indicators such as correlation coefficient (R), variance and root mean square error (RMSE) are computed for the model under multiple regression analysis.

Tribocorrosion is a combined action of chemical and mechanical which causes material degradation during sliding, fretting, rolling, impingement etc. in a corrosive medium. It is very important to study the tribocorrosion behaviour and its testing conditions for the materials. These materials may be either ceramics or polymers or alloys. Further, it is found that tribochemical reactivity of metal is more as compare to ceramic and polymer. Moreover, polymer coatings are helpful to reduce the chemical reactivity of the metal in the presence of a corrosive medium. Therefore, tribocorrosion is an important factor among other factors to decide the application of materials in different environments. Hence, the present chapter has deliberated the tribocorrosion on different materials such as alloy, ceramics, and polymers and remedies suggested by different researchers to avoid tribocorrosion.