Fatigue Of Heavy Vehicle Engine Materials

Due to increasing demands on sustainability exerted by end-costumers and policy makers, heavyvehicle manufacturers are urged to increase the engine efficiency in order to reduce the exhaust gas emission. However, increasing the efficiency is also associated with an elevated fatigue rate of the materials constituting the engine parts, which consequently reduces the engine service life. The aim of the present thesis is therefore to confront the expected increase by studying the fatigue behaviour and damage mechanisms of the materials typically employed in heavy-vehicle diesel engines. With this knowledge, this work seeks to guide the development of new heavy-vehicle engine materials, as well as to develop improved life estimation methods designated to assist the mechanical design of durable heavy-vehicle engines. In essence, a large set of thermo-mechanical fatigue (TMF) and combined thermomechanical and high-cycle fatigue (TMF-HCF) tests is conducted at engine load conditions on laboratory specimens of lamellar, compacted and spheroidal graphite iron. In this way, the fatigue performance and associated damage mechanisms are investigated. In particular, a new fatigue property is identified, the TMF-HCF threshold, which quantifies how resistant a material is to superimposed high-cycle fatigue. The damage mechanism at low temperatures (?500°C) is confirmed to consist of the initiation, propagation and coalescence of numerous microcracks. Based on this, a successful fatigue life estimation model is formulated, allowing accurate estimations of TMF and TMF-HCF tests on smooth specimens, and TMF tests on notched specimens. In the latter case, the microcrack growth behaviour in non-uniform cyclic stress fields and its implications for life estimation are clarified. At elevated temperatures (?500°C), surface oxidation is shown to govern the fatigue performance of cast iron grades intended for exhaust manifolds. It is observed that oxide intrusions are induced, from which surface fatigue cracks are initiated. Consequently, an optimal material at these conditions should have a low oxide growth rate and few casting defects at the surface, as these factors are found to stimulate the growth of intrusion.

Due to increasing demands on sustainability exerted by end-costumers and policy makers, heavy-vehicle manufacturers are urged to increase the engine efficiency in order to reduce the exhaust gas emission. However, increasing the efficiency is also associated with an elevated fatigue rate of the materials constituting the engine parts, which consequently reduces the engine service life. The aim of the present thesis is therefore to confront the expected increase by studying the fatigue behaviour and damage mechanisms of the materials typically employed in heavy-vehicle diesel engines. With this knowledge, this work seeks to guide the development of new heavy-vehicle engine materials, as well as to develop improved life estimation methods designated to assist the mechanical design of durable heavy-vehicle engines. In essence, a large set of thermo-mechanical fatigue (TMF) and combined thermo-mechanical and high-cycle fatigue (TMF-HCF) tests is conducted at engine load conditions on laboratory specimens of lamellar, compacted and spheroidal graphite iron. In this way, the fatigue performance and associated damage mechanisms are investigated. In particular, a new fatigue property is identified, the TMF-HCF threshold, which quantifies how resistant a material is to superimposed high-cycle fatigue. The damage mechanism at low temperatures (/ 500oC) is confirmed to consist of the initiation, propagation and coalescence of numerous microcracks. Based on this, a successful fatigue life estimation model is formulated, allowing accurate estimations of TMF and TMF-HCF tests on smooth specimens, and TMF tests on notched specimens. In the latter case, the microcrack growth behaviour in non-uniform cyclic stress fields and its implications for life estimation are clarified. At elevated temperatures (' 500oC), surface oxidation is shown to govern the fatigue performance of cast iron grades intended for exhaust manifolds. It is observed that oxide intrusions are induced, from which surface fatigue cracks are initiated. Consequently, an optimal material at these conditions should have a low oxide growth rate and few casting defects at the surface, as these factors are found to stimulate the growth of intrusion.

The critical parts of a heavy duty engine are theoretically designed for infinite life without mechanical fatigue failure. Yet the life of an engine is in reality determined by wear of the critical parts. Even if an engine is designed and built to have normal wear life, abnormal wear takes place either due to special working conditions or increased loading. Understanding abnormal and normal wear enables the engineer to control the external conditions leading to premature wear, or to design the critical parts that have longer wear life and hence lower costs. The literature on wear phenomenon related to engines is scattered in numerous periodicals and books. For the first time, Lakshminarayanan and Nayak bring the tribological aspects of different critical engine components together in one volume, covering key components like the liner, piston, rings, valve, valve train and bearings, with methods to identify and quantify wear. The first book to combine solutions to critical component wear in one volume Presents real world case studies with suitable mathematical models for earth movers, power generators, and sea going vessels Includes material from researchers at Schaeffer Manufacturing (USA), Tekniker (Spain), Fuchs (Germany), BAM (Germany), Kirloskar Oil Engines Ltd (India) and Tarabusi (Spain) Wear simulations and calculations included in the appendices Instructor presentations slides with book figures available from the companion site Critical Component Wear in Heavy Duty Engines is aimed at postgraduates in automotive engineering, engine design, tribology, combustion and practitioners involved in engine R&D for applications such as commercial vehicles, cars, stationary engines (for generators, pumps, etc.), boats and ships. This book is also a key reference for senior undergraduates looking to move onto advanced study in the above topics, consultants and product mangers in industry, as well as engineers involved in design of furnaces, gas turbines, and rocket combustion. Companion website for the book: www.wiley.com/go/lakshmi

There are approximately 4,000 fatalities in crashes involving trucks and buses in the United States each year. Though estimates are wide-ranging, possibly 10 to 20 percent of these crashes might have involved fatigued drivers. The stresses associated with their particular jobs (irregular schedules, etc.) and the lifestyle that many truck and bus drivers lead, puts them at substantial risk for insufficient sleep and for developing short- and long-term health problems. Commercial Motor Vehicle Driver Fatigue, Long-Term Health and Highway Safety assesses the state of knowledge about the relationship of such factors as hours of driving, hours on duty, and periods of rest to the fatigue experienced by truck and bus drivers while driving and the implications for the safe operation of their vehicles. This report evaluates the relationship of these factors to drivers' health over the longer term, and identifies improvements in data and research methods that can lead to better understanding in both areas.

This book reviews problems in the mechanical behaviour of cyclically loaded metallic materials, primarily with regard to the nature of the fatigue process. The first edition of the book appeared in 1980. The present second edition represents a revised form of the original book and also covers recent developments in the field. As the book focuses on physical-metallurgical aspects, it occupies a unique and important position in the technical literature, which has so far been devoted mainly to engineering metal fatigue problems and their technical solution in specific practical cases. The book provides a compact review of current knowledge on physical metallurgical processes that accompany and affect the fatigue of metallic materials, and also presents the background for applying the new results to practical designing and to the selection of materials in engineering practice. The authors present an updated review of results from countries both in the east and the west and cover a relatively large field in a concise manner. The work will be of value to research workers and students following advanced and post-graduate courses in the fields of materials science and mechanical engineering.

Fatigue and Durability of Structural Materials explains how mechanical material behavior relates to the design of structural machine components. The major emphasis is on fatigue and failure behavior using engineering models that have been developed to predict, in advance of service, acceptable fatigue and other durability-related lifetimes. The book covers broad classes of materials used for high-performance structural applications such as aerospace components, automobiles, and power generation systems. Coverage focuses on metallic materials but also addresses unique capabilities of important nonmetals. The concepts are applied to behavior at room or ambient temperatures; a planned second volume will address behavior at higher-temperatures. The volume is a repository of the most significant contributions by the authors to the art and science of material and structural durability over the past half century. During their careers, including 40 years of direct collaboration, they have developed a host of durability models that are based on sound physical and engineering principles. Yet, the models and interpretation of behavior have a unique simplicity that is appreciated by the practicing engineer as well as the beginning student. In addition to their own pioneering work, the authors also present the work of numerous others who have provided useful results that have moved progress in these fields. This book will be of immense value to practicing mechanical and materials engineers and designers charged with producing structural components with adequate durability. The coverage is appropriate for a range of technical levels from undergraduate engineering students through material behavior researchers and model developers. It will be of interest to personnel in the automotive and off-highway vehicle manufacturing industry, the aeronautical industry, space propulsion and the power generation/conversion industry, the electric power industry, the machine tool industry, and any industry associated with the design and manufacturing of mechanical equipment subject to cyclic loads.

This text is well established as one of the most autoritative textbooks in the truck and bus industry, having been read by many students and adopted by college lecturers at home & overseas.

Light and Heavy Vehicle Technology, Second Edition deals with the theory and practice of vehicle maintenance, procedure, and diagnosis of vehicle trouble, including technological advances such as four-wheel drive, four-wheel steering, and anti-lock brakes. The book reviews the reciprocating piston petrol engine, the diesel engine, the combustion chambers, and the different means of combustion processes. To counter friction, heat and wear, lubrication to the different moving parts is important. To counter excessive heat which can cause breakdown of lubricating oil films and materials such as gaskets, O-rings, the engine is designed with a cooling system that uses air, water, or engine coolants. Petrol engines use the carburation or injection type of fuel delivery; diesel engines use a high pressure system of fuel injection owing to the higher pressures existing in the diesel combustion chamber. The text explains the operation of the other parts of the vehicle including the ignition and starter system, emission controls, layshaft gearboxes, drive lines, and suspension systems. Heavy vehicles need highly efficient air brakes to stop them compared to the hydraulic brake systems used in smaller and lighter vehicles. The book is suitable for mechanical engineers, engine designers, students, and instructors in mechanical and automotive engineering.

This edition contains new material covering the latest development in electronics, alternative fuels, emissions and diesel systems.