bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Experimental Study of the Apparent Area of Contact under Nominally Hertzian Contact of Rough Surfaces
Authors: Refaie M. El , Halling J. 
Published: June 2010

For bodies in contact it is usual to assume that the real area of contact is proportional to the applied normal load. For Hertzian type contacts the apparent area of contact is also dependent on load. Thus, in contacts of the latter kind the divergence of the apparent contact area from the classical Hertzian predictions leads to further understanding of the actual nature of contact of rough surfaces. In the work reported in this paper, results are presented for experimentally determined values of the apparent contact size in Hertzian conditions over a wide range of applied load. It is demonstrated that the Hertzian values are generally valid at higher loads, provided bulk plastic yielding does not occur. At lower loads the size of the contact zone is greater than that predicted by Hertz, the discrepancy being greater for rough surfaces and the contact being almost independent of the normal load. This confirms the general theoretical prediction for the contact of rough surfaces. The results of such a study, therefore, demonstrate the regime in which the usual Hertzian analysis is valid for defining the apparent contact size. Nonetheless, even where agreement exists, the actual contacts occur only over a discrete population of the surface asperities. The effect of ball size is also shown to be of reducing significance in defining the contact size at small loads, again justifying the basic theoretical arguments. At higher loads it is found that the Hertz solution is substantially valid even where a marked geometric conformity exists between the ball and its track.
An Experimental Study of the Thermal Aspects of Sliding Contacts and Their Relation to the Unlubricated Wear of Steel
Authors: Quinn T. F. J. 
Published: June 2010

Experiments are described in which low-alloy, medium-carbon steel (AISI 4340) pins were slid against discs of the same material under various loads, at a speed of 625 cm/s. The bulk temperatures of the pins and discs were measured continuously, as also were the frictional forces and the volumes of wear. Similar experiments were also carried out, at a much lower speed (about 5 cm/s), in which the bulk temperatures of the specimens were due almost entirely to externally supplied heat. As far as possible, the bulk temperatures, and the corresponding loads, were maintained at the same values as for the initial, frictionally heated, experiments. The wear debris produced during both sets of experiments was examined by X-ray diffraction in order to identify the various components and to analyse their relative proportions. The variation of the proportions of α-iron, rhombohedral oxide, and spinel oxide with measured bulk pin temperature was used to give an estimate of the temperatures occurring in the regions of true contact. This estimate was approximately of the same magnitude as those temperatures measured in recent dynamic thermocouple experiments. The wear results are discussed in terms of oxidation of the real areas of contact at the temperatures indicated by the proportional analysis of the wear debris. It is shown that reasonable values of the activation energy can be obtained from a direct comparison between frictionally heated and externally heated experiments carried out under the same load and the same bulk temperatures. It is concluded that the contact temperature is the factor governing the wear behaviour of steels rather than the ambient temperature of the whole surface.
The Role of Oleophilic Surface in Lubrication
Authors: Groszek A. J. 
Published: June 2010

Surfaces of MoS2 and graphite are composed of ‘oleophilic’ regions, which have a strong affinity for long-chain normal hydrocarbons, and polar regions. The oleophilic regions adsorb hydrocarbons in preference to polar compounds, such as water and alcohols. Conversely, water and alcohols easily displace hydrocarbons adsorbed in the polar sites. A study of MoS2 and graphite having different proportions of oleophilic and polar sites shows that the lubricating effectiveness of these solids increases with the proportion of oleophilic sites on their surfaces. For MoS2 the sites consist of regularly disposed sulphur atoms in the basal planes of individual crystallites, and it is postulated that they can become chemically bonded to steel surfaces. When one basal plane side of a MoS2 crystallite is bonded to the steel surface, the other side presents an oleophilic surface to the surroundings, which has a low surface energy and high affinity for mineral oils. The oleophilic ‘sites’ produced in this way on the metal surface are believed to be instrumental in increasing the load-carrying capacity of the steel surfaces in sliding and rolling contact, especially in the presence of mineral oils.
Paper 6: Fuel Feed Pumps and Filters for Low-Pressure Fuel Supply
Authors: Clarke F. W. 
Published: June 2010

The main essentials of power units and their accessories have not changed significantly over the last 40 years, and fuel feed pumps come into this category. The basic requirements are well established, but there has been a continual striving for improved performance and strenuous efforts to reduce costs in order to meet the vehicle manufacturers' demands. The author has endeavoured to indicate the trends in developments of the various types of fuel pumps, mechanical and electrical, with particular reference to application and performance for petrol and diesel equipment. The importance of correct installation is related to performance and reliability; design materials are discussed, particularly in relation to the influence of fuels and temperature and the need to meet the demands of modern high-output engines. Mention is made of the relationship of fuel feed systems to safety and evaporative emission control and the special requirements of fuel injection installations. The need for efficient fuel filtration is discussed and the application and design details of filters are outlined.
Paper 15: Recent Research and Development in Truck Engine Cooling
Authors: Taylor S. R. G. 
Published: June 2010

To improve economically the cooling performance of trucks an analytical approach was used to assist development. The component tests undertaken included the complete net pressure and power characteristics of two engine water pumps and four engine fans, the heat transfer and pressure drop performances over appropriate flow ranges of some 14 radiators, the additional resistance to air flow offered by two noise shields, and studies of the effects of pump speed, coolant temperature, system pressure, thermostat resistance, and by-pass resistance on radiator water flow with three different engines. The apparatus and methods used for each type of test are outlined. Using the above and other existing data, cooling performance was predicted for some 80 different configurations and conditions, and fan power consumption was predicted for several of these. These results enabled component design and manufacturing problems to be identified and the selection of the most promising configurations for actual development testing. The agreement between the predicted and actual cooling performances is discussed. The use of computer programmes in component testing and analytical prediction is mentioned, and various possible developments in future cooling systems of still higher performance are discussed.
Paper 1: Component Failures in Generating Plant
Authors: Weeks R. J. , Hodges N. W. 
Published: June 2010

The availability of his plant is of prime interest to an operator; in general, this will be governed by the net effect of individual component reliabilities. As the number of components incorporated in a plant increases, there is a tendency for the availability to drop, and thus simplicity in design is frequently favoured. This paper will, however, be principally concerned with the complementary factor, namely the causes of failure or unreliability in individual components. Components normally fail through some deficiency in the design of the plant or component, in the manufacture and erection stages, or due to operation. These ‘time’ bands, to which the root cause of an individual failure may be attributed, also indicate the general nature of the actions to be taken to prevent a recurrence of the fault. The authors have drawn upon their experience as the operators of power plant and find that the ‘time’ bands can be further subdivided into various categories of failure cause. For example, design-stage faults may be due to environmental factors not taken into account, and perhaps unknown to the designer, or they may be due to the use of components unsuitable for the job specified. These various categories are considered and will be illustrated by examples taken from the authors' experiences. The implications of the various categories of failure on plant maintenance and operation will also be discussed.
Paper 2: Safety and Failure Analysis of Large Diesel Engine Pistons
Authors: White D. J. , Enderby L. R. 
Published: June 2010

This paper describes investigations that were undertaken to identify the reasons for fatigue failures in cast iron and aluminium pistons of large diesel engines. The work involved experimental and theoretical stress analyses, and fatigue tests were made on specimens cut from actual pistons. It was found that four pistons which suffered fatigue failures had safety factors of 0·60, 0·68, 0·94, and 0·96, while three modified designs which performed satisfactorily were assessed to have safety factors of 1·1, 1·24, and 1·57. Special attention is drawn to the method of fatigue testing in which features typical of the piston are retained. While it is considered prudent to design for safety factors substantially in excess of unity, the results presented should promote confidence that this approach to the design of components is valid not only in this case but more generally.
Paper 5: Non-Destructive Testing Techniques and Their Relationship to Design Problems
Authors: Birchon D. 
Published: June 2010

The range and sophistication of non-destructive testing techniques now available is capable, with a few exceptions, of finding defects far smaller than those which need to be eliminated from a structure if it is to perform its function satisfactorily. Nevertheless, some unacceptable defects do slip through the present nondestructive testing processes, and these errors must be prevented. One of the principal causes of unnecessary ambiguity and expense in non-destructive testing arises from the sophistication of some of the NDT techniques available today. As a result, the reaction of engineers to non-destructive testing techniques varies between the extremes of blissful confidence in their efficacy, and wary (or even ‘weary’) concern over their uncertainties, limitations, and cost. This unfortunate situation has arisen just at a time when our increasing precision in non-destructive testing techniques, and our better knowledge of material characteristics and sophistication of design procedures, should enable the gap between non-destructive testing and engineering design to be closed. This paper will therefore argue the case for a simple, formalized method of validating non-destructive testing in a way which, it is hoped, can help to rationalize and integrate some of the factors involved in the difficult compromise which lies at the heart of engineering design.
Paper 10: Basic Design—Design for Safety
Authors: Wilks P. M. , Shaw F. 
Published: June 2010

To consider the basis of incorporating safety and reliability into design, it is necessary to understand the design function. We must think in terms of a complete activity, not one concerned only with the safety of automobiles. This is the narrow, present-day popular aspect of safety. It is equally important that safety and reliability shall be of vital concern whether the article being designed is a can-opener or a battleship; both are for the use of people, who must have neither their lives nor their comforts jeopardized by a careless fundamental approach. Good basic design depends on a sound knowledge of the engineering principles, and a clear picture of all available data and facts about the case being considered. It is essential that design begins by giving engineers training in basic principles, and making quite certain that they are able to get at all the relevant facts and knowledge which gives a background to the correct approach. They must also be freely advised of any new methods which may influence the thinking process. The next important aspect of safety and reliability in design is prediction. Without the ability and knowledge to predict how a part will function in practice, even moderately good design is impossible.
Paper 22: Some Causes of Fatigue Failures in Service
Authors: Smedley G. P. 
Published: June 2010

The greater proportion of fractures of engineering components in service display evidence of fatigue crack propagation. Although the fractures are referred to as fatigue failures, it is shown by example that the true causes are: (1) neglect of cyclic service loading; (2) resonant vibrations; (3) increase in service cyclic loadings due to wear or maloperation; (4) material defect; (5) sharp notches; (6) welds and unsound surface deposits; and (7) corrosion or fretting fatigue. Many breakdowns caused by failures involving one or more of these causes could have been avoided at the design stage or during manufacture, operation, or repair of the affected parts.
Gravity Flow of Solids down Vertical Pipes
Authors: McDougall I. R. 
Published: June 2010

Only a small amount of literature has been published on the gravity flow of particulate solids down pipes. Earlier work showed that in such conditions considerable volumes of air could be entrained with the solids, often resulting in considerable air-pressure difference across the ends of the pipe. A model is developed which makes possible prediction of the pressure differences for known flow rates from system parameters. Considering the rather large number of basic assumptions required and the paucity of experimental data, the agreement between theory and practice is fairly good. The model, however, throws little light on the problem of predicting solids flow rates, emphasizing that further work, both theoretical and experimental, is needed.
Disturbance Waves in Annular Two-Phase Flow
Authors: Hewitt G. F. 
Published: June 2010

Many of the important features of annular two-phase flow are governed principally by the existence and behaviour of waves on the interface between the phases. In particular, the annular flow system is characterized by rapid wave growth leading to extremely large waves known as ‘disturbance waves’. By studying these waves, much can be learnt about annular flow. This paper summarizes previously published Harwell work in which a number of parameters of the waves have been established using a variety of experimental techniques, including (1) high-speed ciné studies using both normal and axial viewing; (2) tracking of the waves using flush-mounted conductance probes; (3) continuous film thickness measurements using a fluorescent technique; and (4) velocity measurement using an optical-mechanical stroboscopic device. Extensive data have been obtained on wave frequency, amplitude, velocity, and break-up. If a long enough channel is used, the wave frequency and velocity become constant. It is likely that wave growth continues but that break-up of the waves occurs giving rise to liquid droplet entrainment which is balanced by droplet redeposition, thus giving a quasi-stable situation. Although the frequency becomes constant, the waves are by no means periodic. The fluorescence measurements show that the waves have an amplitude about five times greater than the mean film thickness and that the wave has an axial size of about the same order as the tube diameter. The large amplitude of the waves is confirmed by the axial view photography which also demonstrates large and transient amplitude variations around the inner periphery of the wave.
Paper 1. Friction Clutches and Clutch Control Mechanisms
Authors: Davies D. A. 
Published: June 2010

Part 1 of this paper states the basic requirements of clutches and then discusses the various factors which must be considered in the initial stages of clutch design and specification for particular applications. The differing types of clutches used over a wide range of operating conditions are described and changes likely to be seen in future designs are mentioned. A small section is devoted to facing friction materials which are one of the most important components of the clutch. Finally the steps taken to ensure satisfactory performance in a specific vehicle model are explained. Part 2 first considers the basic requirement and characteristics and then the ergonomic factors involved. There are three common methods of control, two being mechanical, namely lever and rod system and cable system, and the third hydraulic, all of which are discussed in some detail. With each of these methods some form of power assistance may be necessary to ensure a satisfactory pedal load and the various methods by which this can be achieved are considered.
Experimental and Theoretical Studies of Burning Drops of Hydrocarbon Mixtures
Authors: Chen C. S. , El-Wakil M. M. 
Published: June 2010

This paper presents an experimental and theoretical study of the self-ignition and burning behaviour of drops of hydrocarbon mixtures. In the experimental work, the mass histories, as well as temperature, shape, and flame histories, of drops of heavy hydrocarbon mixtures, suspended on fine thermocouple beads and subjected to heated air streams, were obtained. Due to thermal decomposition and irregular burning, the masses could not be determined from temperature and size and were measured by a liquid-nitrogen quenching technique. Temperature, flame, and shape histories were obtained in the usual manner by thermocouple and photographic means. Drops of grade 6 fuel oil and grade 6 fuel oil minus its asphaltene constituent, of 1·2 and 1·7 mg initial mass, subjected to 1450 and 1600°F air-stream temperatures, were studied. The drop histories can be divided into four phases: (1) pre-ignition, (2) self-ignition and combustion, (3) thermal decomposition, and (4) carbon residue, or cenosphere, burning. The asphaltenes contributed a great deal to burning irregularities but not to burning rates or temperatures. The latter were higher the higher the air temperature, but were affected less by changes in air velocity. In the theoretical work, a generalized treatment predicting the histories of drops undergoing unsteady vaporization, burning, thermal decomposition, or combinations of these was formulated. Based on a spherically symmetric model, governing equations of state, continuity, chemical species conservation, and energy conservation were solved with the aid of simplifying assumptions. A computer program was developed covering a wide range of operating conditions. The theoretical model showed reasonable agreement with the experimental results. A universal plot estimating drop histories of heavy residual fuels was prepared. The distribution of the total heat input into sensible heat, latent heat of vaporization, and endothermic heat of decomposition was also plotted versus dimensionless time.
Paper 1: Critical Factors in the Application of Dual-Fuel Engines
Authors: Eke P. W. A. , Walker J. H. , Williams M. A. 
Published: June 2010

A dual-fuel engine may be defined as a compression-ignition engine using mainly gaseous fuel but with a small quantity of fuel oil injected as an ignition source; the engine can be changed over instantaneously and under load to operate on liquid fuel alone. The recent availability of natural gas in this country once again attracts the attention of engineers towards gas as a fuel for internal-combustion engines. This paper traces the development of dual-fuel engines, originally using sewage gas and more recently using natural gas, and considers their advantages, both technical and economic, compared with spark-ignited and diesel engines. The dual-fuel engines within the authors' experience are described. The critical factors in handling natural gas in its liquid form are considered, and the extended scope of dual-fuel engines and alternative fuel engines in mobile applications is briefly reviewed. Finally, the paper examines the future for dual-fuel engines and suggests directions in which further development is required.
Paper 9: Fuel-Injection System Requirements for Different Engine Applications
Authors: Howes P. 
Published: June 2010

Modern diesel engines are used in a wider variety of applications, installations, and environments than probably any other power unit. It is quite common for one engine type to be used for tractors, automotive, industrial, and marine purposes, with very little change to the basic engine. Considerable changes are necessary in the fuel-injection system, however, to meet the varying torque curve, speed range, and governing requirements. Operation over a wider range of temperatures and viscosities is often needed, and noise and smoke legislation have added further requirements. The paper outlines these problems and the compromises that must sometimes be made. Direct-injection and indirect-injection engine cases have been considered. The paper concludes with some comments on pre-setting fuel pumps for high-volume production.
Paper 10: Laboratory Simulation of Field Load Spectrum
Authors: Singh G. 
Published: June 2010

This paper presents details of a laboratory simulation of field load spectrum program developed and being implemented at the Advanced Project Engineering Division of Massey-Ferguson. The aspects of data acquisition, data reduction, and laboratory simulation are discussed. Data acquisition includes calibration of transducers and indexing or control pulse coding of the analog tape to assist subsequent processing of data on a digital computer system. Data reduction involves analog-to-digital conversion, binary conversion, calibration, collection of useful portions of raw digitized data, transformation of data to their proper engineering units and analyses of data in time and/or frequency domains. Laboratory simulation is accomplished in two basic forms: (1) Controlled dynamometer testing, utilizing weighted composite load–frequency histograms derived from the field data, is preferred for complex mechanical systems with high inertia undergoing variety of loads with severe extremes. (2) Shaker testing, utilizing electromagnetic and electrohydraulic shakers, is preferred for structural testing of entire mechanical systems or their components by providing a duplication of field vibrations through a closed-loop magnetic tape control. Power spectral density analyses of the random signals (involving input forcing functions to the mechanical systems) are performed to correct for the frequency response characteristics of the shaker systems and the mountings used for the testing. The pertinent load spectrums can also be synthesized from their corresponding power spectra by using a white noise generator as the input device in place of the closed-loop analog tape playback system.