bluuebunny/crossref_metadata_2025 huggingface dataset:
A Computer Aided Manufacturing Procedure for Experimental Two-Dimensional Aerofoils
Authors: Al-Kayiem H H , Day A J , Bruun H H
Published: February 2007

The manufacture of experimental aerofoil sections to a specific profile is generally an expensive and time consuming part of aeronautical research. This paper describes a computer aided manufacturing procedure that has been developed for the production, in a small research engineering workshop, of experimental wing models required for investigation of the separation of flow from an NACA 4412 aerofoil section. A 2 1/2 axis CNC vertical milling machine has been programmed with coordinates generated by computer from the NACA 4412 defined profile, to produce aerofoil sections which are then built up into a wing model.

The method is fast and accurate, enabling the time and cost of manufacture to be substantially reduced, at the same time improving the accuracy and quality of the model. The procedure has been developed as a computer program and is also used as a case study teaching aid in computer aided manufacture.
Model Spaces and their use in Mechanism Simulation
Authors: Leigh R D , Medland A J , Mullineux G , Potts I R B
Published: February 2007

Computer aided design systems tend to work simply in terms of geometric entities. Any intelligence that could be implanted in the system would, however, need to deal with the function of the design being described. This requires the system to handle the geometry at a higher level. One approach is to use model spaces that hold groups of geometric entities and preserve some of the associations between them. A software system is described that works in terms of such spaces and allows hierarchies of spaces to be built up. The hierarchy, however, is not sufficient for a complete description of every design. There is a need to add extra constraints. The software allows these to be entered and automatically tries to maintain them as being true. The use of this approach is illustrated by the simulation of the motion of a mechanism from a high-speed packaging machine.
The Production and Properties of Copper-Iron Particulate Composite Wire
Authors: Lawal G I , Barton D C , Bramley A N , Nutting J
Published: February 2007

A novel means of producing copper-based powder metallurgy wire containing sufficient iron in particulate form to impart useful magnetic properties has been investigated. The method, which involves encapsulating a powder mixture within a copper tube prior to rolling and die-drawing operations, has been successfully used to produce composite wire of diameter range 1.8-0.4 mm. Particular attention has been paid to the effect of composition, processing strain, heat treatment and iron particle size on the electrical, mechanical and magnetic properties of the wire. Microscopy studies have also been carried out to determine structural changes in the material during processing.

It was found that the good conductivity and ductility of solid copper wire was not greatly reduced provided (a) the iron content of the composite wire was kept fairly low (<6 per cent) and (b) the annealing temperature was not sufficiently high for significant alloying to take place (650°C maximum). Saturation magnetization values increased with increasing process strain, as did the magnetic hardness. The latter, however, could be minimized by fully annealing the iron after processing the wire. The magnetic properties were undoubtedly influenced by the size and shape of the iron particles, smaller particles being more easily elongated and tending to give greater magnetic hardness.
Carrington: Innovative Change Transforms a Traditional Manufacturing Site
Authors: Cowl B J , Graham G N , Thomas C Curtis , Thompson R K
Published: February 2007

This paper describes how a petrochemical plant at Carrington, near Manchester, has reversed spiralling losses and rescued both its economic viability and its self-esteem.

It charts the steps taken to transform a traditional, hierarchical structure into an open, multi-skilled approach to chemicals manufacture, and it seeks to demonstrate how fundamental changes in work practices and organization have impacted on the financial performance of a manufacturing site.
A Study on Heat and Mass flow in Stationary Gas Tungsten arc Welding using the Numerical Mapping Method
Authors: Kim S D , Na S J
Published: February 2007

The phase changing problem at the liquid-solid interface that occurs during stationary gas tungsten arc (GTA) welding has been studied by considering the four driving forces for weld pool convection, that is the electromagnetic force, the buoyancy force, the aerodynamic drag force and the surface tension force at the weld pool surface. In the numerical simulation, difficulties associated with the irregular shape of the moving interface have been successfully overcome by adopting a boundary-fitted coordinate system that eliminates the analytical complexity at the liquid-solid boundary. This method also has the capacity to handle the time-dependent changing solution domain of the moving boundary problem and could be applied effectively to this transient weld pool development problem with the moving boundary and phase change condition.
A Strategical Approach to Computer Integrated Manufacture
Authors: Franks I T , Gorman J
Published: February 2007

Many companies are now resolutely investigating the possibilities of making a substantial investment in computer integrated manufacture (CIM), with the purpose of improving business competitiveness through appropriate and effective manufacturing control. This paper proposes the importance of choosing a strategical approach to analysis and design which makes use of sound methodologies and tools. A case study of such an approach is described, up to the construction of the statement of requirements and invitation to tender. Emphasis is given to the IDEF0 methodology as being central to the success of the study.
Energy Absorption and Deformation Modes of Thin PVC Tubes Internally Grooved When Subjected to Axial Plastic Collapse
Authors: Mamalis A G , Manolakos D E , Viegelahn G L , Johnson W
Published: February 2007

Theoretical and experimental investigations into the quasi-static plastic collapse of thin-walled PVC tubes containing a number of geometrical discontinuities in the form of internal axial grooves of constant depth, with the aim of providing information about its behaviour as an energy-absorbing device, are reported. An inextensional collapse mechanism for folding the shell in a non-symmetrical diamond fold mode, taking into account stationary, circumferential, inclined and travelling plastic hinges, is considered. The failure modes and the mean postbuckling load necessary to perform the operation are discussed. Predicted results based on the collapse modes encountered, when compared with those obtained experimentally were found to be in good agreement.
Stress Tensor Measurements within the Vaneless Diffuser of a Centrifugal Compressor
Authors: Maksoud T M A , Johnson M W
Published: February 2007

Distributions of normal and shear (Reynolds) stresses inside the vaneless diffuser of a low-speed centrifugal compressor are presented. The measurements were made using a triple hot-wire system and a phase lock loop sampling technique. Results were obtained on cross-sectional planes at eight radial stations between the impeller outlet and the diffuser exit at three different flowrates. The turbulence was highly anisotropic and became more so as the flowrate was increased. The tangential component of turbulent intensity was found to be significantly smaller than either the radial or axial component. The blade wake observed at the diffuser inlet decays very rapidly due to the strong tangential Reynolds stresses generated by the opposed secondary flows on either side of the wake. The passage wake decays very much more slowly and is still identifiable at the diffuser discharge.
Gun Recoil System Performance Measurement and Prediction
Authors: Hajihosseinloo M A , Hooke C J , Walton D
Published: February 2007

The performance of high-energy gun recoil absorbers, usually referred to as gun buffers, for use in military fighting vehicles is investigated. A test facility built to simulate gun reaction loads imposed on recoil absorbers is described and a theoretical model to predict their performance is derived. This model, which predicts the recoil velocity and the pressure variation within a buffer, allows the effects of variation in orifice area, recoil mass and energy to be investigated, together with mechanical compliance, buffer oil density, compressibility and aeration. Theoretical predictions agree closely with data obtained from the test facility and from field trials.
An Analysis of Non-Linear Deformation of Bonded Rubber Mounts
Authors: Shariff M H B M
Published: February 2007

An approximate analysis is developed for non-linear (finite) plane and axisymmetric strain deformations of rubber blocks bonded to rigid end-plates. The analysis is partly based on the works of Klingbeil and Sheild(1) and Gent and Lindley(2). The solutions obtained are explicit and are comparable with published experimental results and expected behaviours. The solutions to the corresponding infinitesimal deformation are exactly the same as those obtained by Gent and Lindley(2) and Shariff(5) (when v = 0.5).
Elastohydrodynamic Lubrication of Heavily Loaded Circular Contacts
Authors: Kweh C C , Evans H P , Snidle R W
Published: February 2007

The paper is concerned with theoretical analysis and experimental measurement of lubricant film thickness in heavily loaded elastohydrodynamic contacts in which the area of elastic deformation is approximately circular. The inverse elastohydrodynamic technique for numerical analysis of contacts of this type described by Evans and Snidle(9) has been used to produce solutions covering a wide range of conditions representative of engineering practice. Detailed solutions for film thickness and pressure have been obtained for conditions giving rise to maximum contact pressures of up to 4.1 GPa with steel surfaces and a mineral oil lubricant. On the basis of these results charts for film thickness have been constructed using the non-dimensional groups proposed by Moes and Bosma(12). Experimental measurements of film thickness have been made using the optical interferometry technique. The conditions used in the experiments have been numerically analysed to provide a direct comparison between theory and experiment. The comparison shows excellent agreement between the theoretical predictions and corresponding experimental measurements.
Dehumidification of Turbulent Air Flow over a Thick Fin: An Experimental Study
Authors: Coney J E R , Kazeminejad H , Sheppard C G W
Published: February 2007

An experimental study has been carried out to investigate the performance of a vertical rectangular fin of finite thickness and moderate size when dehumidification occurs in turbulent flow. Tests were conducted for various free-stream velocities and relative humidities for a blunt leading edged fin under both dry and wet conditions. Further tests were also devised for an attached elliptical leading edge. Lower dry and wet fin surface temperatures were recorded for an elliptical leading edge due to the absence of flow separation and reattachment. During dehumidification tests, water droplets of various sizes formed on the surface of the fin. On the basis of visual observation, for a clean surface, no film condensation occurred. Using the theoretical model reported in reference (1) and the measured fin surface temperatures, heat-transfer correlations in terms of Nusselt and Reynolds numbers were developed. These correlations allowed the effect of simultaneous heat and mass transfer to be estimated. Dry and wet fin efficiencies were also determined for both blunt and elliptical leading edges using the measured fin surface temperatures.
Crack Propagation in Mixed-Mode Ductile Fracture with Continuum Damage Mechanics
Authors: Chow C L , Wang J
Published: February 2007

This paper presents a crack propagation model based on an anisotropic theory of continuum damage mechanics proposed earlier by the authors capable of characterizing sub-critical crack growth in mixed-mode ductile fracture. The embedded β angles of mixed-mode specimens include 75, 60, 45 and 30 degrees. The crack growth criteria chosen are essentially those developed for crack initiation and are postulated as:

1. A crack propagates in the direction of maximum effective damage equivalent stress αd. 2. The threshold condition of crack initiation is satisfied when the overall damage w in an element ahead of the crack tip at the prospective crack growth direction reaches its critical value, wc.

The crack growth behaviours of the mixed-mode specimens are analysed using a finite element formulation of the non-proportional loading based on the anisotropic model, and the predicted and measured results are found to be satisfactory. The proposed model is also adapted to predict the critical loads of unstable crack propagation and the results are compared favourably with those determined experimentally. Hence the application of the above two fracture criteria can be made to address the entire history of crack development from initiation to rapid growth.
Effect of Elevated Temperatures on Characterization of Rubber Fracture
Authors: Chow C L , Sze K Y
Published: February 2007

The recent emphasis on improving tyre structure integrity against premature failures has led to an increased effort to study fracture behaviour of different carbon black reinforced tyre compounds. Due to the general hysteretic nature of tyre materials, the overall working temperature of a tyre is elevated under service conditions.

Relative merits in the characterization of crack initiation in a typical tyre compound using the conventional quasi-static energy and J-integral approaches were first examined. The quasi-static energy method has been applied to evaluate the fracture toughness of materials exhibiting either linear or non-linear elastic behaviour within the confines of the linear elastic energetic approach. Based on the ease of analysis and ability to make multiple measurements on a single specimen, the quasi-static energy approach is chosen to measure the fracture toughness of the tyre material at temperatures of 23, 37, 52, 62 and 73°C.

The fracture toughness measured for the tyre material has been observed to be inversely proportional to the temperature elevation. The observation agrees with earlier investigations that the crack growth rate of rubbers under fatigue loading decreased with an increase in temperature in the test materials.
Inlet Pressure and Cavitation Boundary Effects on the Orbit Jump Phenomenon in Squeeze Film Damper Operation
Authors: Feng N S , Hahn E J
Published: February 2007

The theoretical analysis of squeeze film dampers requires a knowledge of the pressure distribution in the oil film, integrated to predict the fluid film forces. For film pressures below atmospheric, even though the more accurate 0-film model (wherein pressures below absolute zero are assumed to be at absolute zero) is utilized in preference to the more commonly used π-film model, the bi-stable or jump behaviour of circular orbit type dampers is incorrectly predicted. This investigation shows that the jump behaviour is not only dependent on the bearing parameter and unbalance but is also extremely sensitive to the inlet pressure to the damper and, indeed, to the exact determination of the cavitation boundary. Experimental results showed poor agreement with theoretical predictions, with jump obtained in theoretically jump-free regions. This discrepancy is probably due to uncertainties in the inlet pressure, the bearing parameter and particularly the precise location of the cavitation boundary. Qualitatively, however, it is confirmed experimentally that the higher the inlet pressure, the less likely that ‘jump’ will occur.
Using an Encoder as a Torsional Vibration Transducer
Authors: Smith J D , Echeverria-Villagomez J S
Published: February 2007

The use of a standard rotary encoder as a torsional vibration transducer is described. Its performance is compared with that of a standard seismic transducer and the relative advantages and disadvantages discussed.
Application of Multi-Grid Methods for Solving the Navier-Stokes Equations
Authors: Demuren A O
Published: February 2007

This paper presents the application of a class of multi-grid methods to the solution of the Navier-Stokes equations for two-dimensional laminar flow problems. The methods consist of combining the full approximation scheme-full multi-grid technique (FAS-FMG) with point-, line- or plane-relaxation routines for solving the Navier-Stokes equations in primitive variables. The performance of the multi-grid methods is compared to those of several single-grid methods. The results show that much faster convergence can be procured through the use of the multi-grid approach than through the various suggestions for improving single-grid methods. The importance of the choice of relaxation scheme for the multi-grid method is illustrated.
Discrete-Time Control of Fast Non-Linear Motion of Robot Manipulators with Ideal Actuators
Authors: Pan D , Sharp R S
Published: February 2007

Non-linear and coupled dynamic equations of motion automatically generated by computer in algebraic form are piecewise linearized and discretized to form a set of state difference equations by which a mathematical basis is provided for computer control, numerical integration and simulations. Two adaptive control strategies are proposed to drive robot manipulators to follow desired trajectories. The first strategy uses the idea of the combination of feedforward plus feedback control. A complete on-line control scheme is designed in the second strategy. All the calculations, both on-line and off-line, are performed by step-by-step optimization so that a quadratic function is minimized for each step. The control delay associated with time taken for on-line computation is eliminated by a state-and-control prediction strategy. Based on the proposed strategies a general FORTRAN program has been developed for simulations. An example is taken to investigate the tracking ability of robot manipulators in trajectories with different velocity amplitudes and various frequencies by simulations. The tracking ability is also examined by using a random trajectory generator.
Prevention of Input Saturation in Adaptive Positioning Control of an Electrohydraulic Servo System
Authors: Ukrainetz P R , Nikiforuk P N , Hori N
Published: February 2007

The paper deals with the adaptive positioning control of a single-input-single-output electrohydraulic servo system which employs an input filter. This filter spreads a large control input over a period of sampling instants to prevent input saturation. As well, its use enables the proof of stability to be achieved using the standard technique even for unstable plants. A controller structure, which does not require feedback from the output of the input filter, is determined by considering the input filter to be a part of the unknown plant. The design is described in discrete-time form using the Euler operator which has better characteristics than the z operator in many respects. The simulation results are presented to show the performance of the controller.
Numerical Calculations of the Flow in Annular Combustor Dump Diffuser Geometries
Authors: Koutmos P , McGuirk J J
Published: February 2007

A method for calculating the turbulent isothermal flow in axisymmetric annular dump diffuser geometries is described and appraised. The calculation method is based on the numerical solution of the time-averaged transport equations for momentum, continuity, turbulence kinetic energy and energy dissipation, using a finite difference formulation. A boundary-fitted curvilinear orthogonal grid obtained from a solution of the inverse Laplace equations is used to represent the curved combustor head accurately and reduce numerical diffusion errors due to better alignment of the flow streamlines with the grid lines. Comparison between predicted results and measurements indicates that variations in (a) the overall pressure recovery and (b) the loss coefficient performance of the dump diffuser system, with changes in diffuser design features (for example inner/outer annulus mass flow split or dump gap), can be predicted to within 7 per cent of the inlet dynamic head without adopting a more refined turbulence closure. The method is therefore demonstrated to be a useful design tool for dump diffuser geometries.
The use of Indentation Tests to Determine the Fracture Toughness of Brittle Materials
Authors: Hills D A , Li Y
Published: February 2007

The types of crack that may occur upon indenting highly brittle materials are first reviewed. This leads to a speculation on the source of driving stresses for these various types of crack, and then recent results for the stress intensity factors are presented. Some experimental work, permitting the fracture toughness of glass to be found, is described, which is compared with data obtained from four-point bend specimens.
The effect of Uniform Spanwise Vorticity on the Two-Dimensional Flow Through Cascades
Authors: Andrew D N
Published: February 2007

An inherent characteristic of the flow in regenerative turbomachines is the presence of a uniform vorticity in the blade-to-blade plane. Control volume arguments indicate that the effect of this spanwise component of vorticity is to modify the loading on the blades, and modified forms of the Zweifel aerodynamic loading coefficient and the Lieblein compressor diffusion factor are derived to account for this effect. A method for calculating two-dimensional flow through cascades with a uniform spanwise vorticity is described, and results are presented which illustrate the increase in loading and deviation due to the presence of the vorticity.
Numerical Derivation of FRF Matrices for Curved, Twisted and Rotating Beams
Authors: Imregun M , Tsoutrelis A.
Published: February 2007

With recent advances in digital computers, frequency response function (FRF) coupling has become a widely used analysis tool for a range of turbomachinery components, such as blades and discs, and this appproach has the distinct advantage of being based on a closed-form solution, thus not requiring a large number of elements to obtain reasonable accuracy. The problem, however, lies in the unavailability of tabulated expressions for geometries more complicated than straight beams or uniform discs, and hence the resulting model is rather too simplistic. This paper deals with the numerical evaluation of FRF matrices for twisted and rotating beams from knowledge of the governing differential equations in an attempt to refine the state-of-the-art stationary multi-stage uniform beam model of turbomachinery blading.
The Computation of Secondary Flow in a 90° Rectangular Cross-Section Bend
Authors: Johnson M W
Published: February 2007

An explicit time-marching scheme for incompressible inviscid three-dimensional flow is presented. The procedure uses an alternative method to the pseudo compressibility technique and uses the energy equation in place of the continuity equation. Calculations are performed for predicting the strong secondary flows produced when a shear flow enters a 90° bend with a rectangular cross-section. Good agreement is achieved with experimental results and rotation of the Bernoulli surfaces through almost 180° is obtained. Discrepancies in the predictions are largely due to the absence of the viscous terms in the computational model equations.
Deformation Characteristics of Crashworthy Thin-Walled Steel Tubes Subjected to Bending
Authors: Mamalis A G , Manolakos D E , Baldoukas A K , Viegelahn G L
Published: February 2007

The collapse behaviour and crashworthy characteristics of cantilever circular tubes subjected to bending are studied both theoretically and experimentally. Three different fixture devices were used and their effect on failure behaviour of the tube was investigated in detail. A theoretical method, proposed by Hodge, slightly modified, is used to analyse the elastic and elastoplastic phases of bending, while a rigid-perfectly plastic analysis is developed to describe the plastic bending phase. Agreement between experimental and theoretical results was found to be quite good.
Techniques in Design for Manufacture
Authors: Swift K G
Published: February 2007

The aim of this series of papers on design for manufacture is to identify the current position in the development and exploitation of techniques and help point to the areas where further work is needed. In this general overview to the issue, the problems of designing for manufacture are introduced and the issues of training, methodical design procedures and computer integration are also touched on.
Roads to Engineer
Authors: Nevitt P J
Published: February 2007

The 1989 Chairman of the Automobile Division gives a brief career history, an informative view of the world vehicle industry, and a personal view of the future education of engineers stressing the need for the profession to adopt a more global approach.
An Investigation of the Liquid Petrol Wall Film in the Manifold of a Carburetted Spark Ignition Engine: Effect of Carburettor and Manifold Geometry on Wall Film Quantities, Engine Performance and Emissions
Authors: Hasson D A , Flint W L
Published: February 2007

The rate of deposition on the manifold wall of liquid droplets from the multi-component, two-phase stream of fluid flowing in the inlet manifold of a carburetted petrol engine and the re-entrainment of droplets into the stream from the liquid film which flows on the walls have been investigated using a single cylinder crossflow engine. The effect of throttle opening, straight manifold length, a smooth bend and a mitre bend is reported: measurements of exhaust emissions and cycle-to-cycle pressure variation of cylinder pressure are related to wall film quantities.

It was found that throttle position was important in determining the initial wall film, that the average thickness of the film decreases with length along the straight manifold and that droplet re-entrainment from a sharp bend is greater than from a smooth bend. Removal of the wall film yields a significant reduction in the emission of unburned hydrocarbons and virtually eliminates cycle-to-cycle variations of pressure in the engine cylinder.
A Tribological Study of Synchronizing Devices Used in Car Gearboxes
Authors: Denizot D , Roques-Carmes C , Monteil G , Lonchampt J
Published: February 2007

Tests were carried out using a computerized test-bench that allowed typical vehicle synchronizers to be studied. Comparisons were then made possible between two different sychronizing devices (new-process, Borg-Warner). The various phases characterizing synchronization were put into the equation, taking account of the kinetic and geometric parameters of the synchronizer components. Studies by ESC A showed that the reactional mechanism under sliding was based on an additive adsorption process.
The Use of Viscous Couplings to Alleviate Transmission Wind-Up in Military Vehicles When Driven On-Road
Authors: Hall L C , Moss P J
Published: February 2007

Many of the high-mobility wheeled vehicles used by the British Army employ permanent all-wheel drive transmission systems with just one transverse differential. Since all the wheels on each side of the vehicle rotate at the same angular velocity severe transmission wind-up can be developed on roads.

The possibility of using viscous couplings to alleviate this problem has been investigated by computer simulation backed up by practical trials on a 4 × 4 armoured reconnaissance vehicle. The results suggest that with a suitable choice of coupling characteristic this solution can dramatically reduce the wind-up torque during low-speed manoeuvres with no significant effect on off-road mobility or handling on roads. It can reduce the wind-up caused by non-uniform tyre wear but not to the extent anticipated. To safeguard handling stability under heavy braking there may be a need to bias the brake effort distribution to the front.
Integrated CADCAM and Automotive Die and Mould Manufacture
Authors: Johnson A R
Published: February 2007

Many automotive components are produced in very large quantities using manufacturing processes such as casting, moulding and forging. These processes require tooling which usually has geometrical complexities such as doubly curved surfaces, fillet curves, split lines and draft angles. Traditionally the component design is conveyed to the toolmaker for manufacture of the tooling, using conventional engineering drawings. The paper shows how tooling and component problems can arise due to the inability of conventional two-dimensional engineering drawings to unambiguously define complex three-dimensional shapes. Modern fully integrated computer aided design and computer aided manufacturing (CADCAM) systems may be used to overcome these problems. This is achieved by producing numerically controlled machining information to manufacture the tooling directly from the computer generated component design, thus eliminating the ambiguities associated with conventional engineering drawings. The use of a fully integrated CADCAM system for the design and manufacture of automotive components and tooling is described, and the technical and economic advantages gained from its use are detailed.
W O Bentley—The Man and his Engineering
Authors: Bastow D
Published: February 2007

This paper covers career details, connecting themes and achievements of W. O. Bentley. Consideration is given to: aluminium pistons; World War I rotary aero engines; Bentley and Lagonda production cars between the wars and after World War II; the Armstrong Siddeley prototype.
Advanced Techniques for Engine Research and Design
Authors: French C C J
Published: February 2007

This paper discusses technical improvements that have been made to internal combustion engines in the recent past. It then goes on to show that, with the availability of the high-speed computer, great possibilities exist for many more advances to be made in design and performance.
A Study of the Correlation between In-Cylinder Air Motion and Combustion in Gasoline Engines
Authors: Kyriakides S C , Glover A R
Published: February 2007

This paper describes an investigation into the effects of in-cylinder air motion at the spark plugs on gasoline engine performance. Measurements of combustion angles have been made in a single-cylinder four-stroke disc combustion chamber engine at part load and MBT ignition timing. Seventeen in-cylinder air motion regimes have been produced using masked valves. The air motion in each build has been evaluated by making laser Doppler anemometry (LDA) measurements of mean velocity and turbulence intensity at the spark plug position under motored conditions.

It has been shown that there is a strong correlation between turbulence intensity and 10–90 per cent burn angle. It is demonstrated that for this combustion chamber geometry a tumbling air motion is a more effective means of generating turbulence at TDC than swirl.
Combustion Ignition Delay in Engines with Unconventional Piston Motions
Authors: Craven K K , Smith J E , Clark N N
Published: February 2007

Ignition delay is an important parameter in determining diesel engine performance and efficiency and has a profound effect on the ability of an engine to start in cold conditions. With declining fuel quality and increasing interest in unusual fuels, this topic must be addressed for future engine designs. A literature survey has revealed that models of the type proposed by Wolfer are preferred. This model has been used to show that the piston motion in an engine can have a significant effect on ignition delay and cold-start performance. In particular, it was readily demonstrated that a sinusoidal motion (as imported by a Stiller-Smith mechanism) and an inverted slider-crank motion both offered superior performance to a conventional slider-crank motion.
A Review of the Role of Vehicles in Agriculture
Authors: Dwyer M J
Published: February 2007

Agricultural tractors have been developed over the years to carry out almost every operation on the farm. However, they are not ideally suited to all these tasks and it may be more economical, in certain situations, to use more specialized vehicles. In the extreme, one could perhaps imagine four different types of agricultural vehicles, for heavy draught work, transport, low ground pressure applications and materials handling. Computer models are being developed to evaluate the potential economic benefits that might be achieved by the introduction of such specialized vehicles on particular farms. Models already exist for predicting tractive performance and average speed over different types of terrain. Further models are needed for manoeuvrability and some other aspects of performance.

Mechanization of farming throughout the world has been based on the agricultural tractor. Introduced originally as a replacement for draught animals, it has now been adapted to carry out almost every job on the farm. Nevertheless, it is still the requirement to pull ploughs and other cultivation implements that mainly determines its design specification. This has led to the development of a slow, heavy, unsprung vehicle with large diameter, low inflation pressure driving wheel tyres. This design, with two driving wheels at the rear for the lower power ranges and all four wheels driven for higher powers, is reasonably well suited to carrying out heavy draught operations in the field while maintaining sufficient mobility to be useful for other jobs. The range of other jobs for which the agricultural tractor has been adapted has increased steadily over the years so that it would not be difficult to list perhaps forty or fifty. As far as their effect on the vehicle design specification is concerned, however, they can be grouped into relatively few classifications. Apart from cultivations, they comprise operations where transport of large quantities of materials is an important component—operations such as harvesting, spraying and fertilizer distribution, where neither tractive effort nor transport of materials is a major part, and materials handling. Obviously these are not strictly defined categories and many tasks will contain some elements of two or more of these classifications. However, they are useful in considering the design specifications for agricultural vehicles.
Corrugation of Unmetalled Roads Part 1: Vehicle Dynamics
Authors: Misoi G K , Carson R M
Published: February 2007

The paper considers the dynamics of a vehicle running over a developing corrugation on an earth or gravel road. Theoretical models are used to show that the maximum contact force is imposed on or near the corrugation crest. Full-scale rolling rig experiments confirm this. Field observations show that the great majority of vehicles travel over corrugations at speeds that are above both the sprung and unsprung resonances. Hypotheses of road corrugation are discussed in the light of the results.
Stiller—Smith versus Conventional V-8 Bearing Load and Friction Comparisons
Authors: Smith J E , McKisic A D
Published: February 2007

The Scotch yoke in its various forms and inversions has received considerable attention as a possible alternative to the slider-crank for internal combustion engine use. As a recent entry, the Stiller-Smith mechanism has shown promise as being a viable and strong option. Kinetostatic models were formulated to determine loading within similar eight-cylinder, four-stroke, compression-ignition engines. Emphasis was placed on comparing the number and similarity of mechanism components, implications of component and linkage motions, and the severity of loading experienced by similar bearing surfaces within the engines. It was found that journal bearings in the slider-crank engine were more severely loaded than those in the Stiller-Smith engine. The linear reciprocating bearings in the Stiller-Smith engine were more heavily loaded than the slider-crank piston skirts. Implications of these and other results are discussed.
Concept Design of a Low-Noise Industrial Engine
Authors: Sawer J M , Ford-Dunn M D
Published: February 2007

A fundamental re-evaluation of industrial engine design concepts is made to take into account modern environmental demands. A range of diesel and gasoline powerplants, incorporating many low-noise features, is suggested.
Measurement and Modelling of Ignition System Energy and its Effect on Engine Performance
Authors: Stone C R , Steele A B
Published: February 2007

This study investigates the effect of ignition parameters on the cyclic dispersion and the specific fuel consumption of a carburetted single-cylinder engine. Ignition energy measurements were made on the low- and high-voltage sides of the ignition coil, and the performance was predicted satisfactorily by a simple model with passive elements. The spark energy was varied by changing the spark plug gap and the coil-on-time. The spark energy was measured in a special calorimeter: the aim was to find a correlation between engine performance and the spark energy measured by the calorimeter. The tests were conducted at part load and low speed with a weak mixture, as these conditions are known to give high levels of cyclic dispersion.

The spark calorimeter showed a higher spark plug conversion efficiency for spark plugs with large gaps. However, the spark plug gap was found to be a more significant determinant of engine performance than the spark energy measured by the calorimeter. The experimental results are preceded by a review of ignition phenomena and their influence on combustion.
Steel—a Metal and a Material
Authors: Morris C E H
Published: February 2007

This lecture, given by the President of the Institute of Metals, reviews some of the changes that have occurred in steelmaking during the past 50 years, and illustrates how steel has become an important part of the developing world of materials. It describes how selection of high-quality raw materials and changes in methods and scale of production have resulted in improved output, reduced energy consumption, and materials suitable for present-day applications such as offshore installations. It discusses the importance of materials for all engineers and related disciplines, and then outlines how the Institution of Mechanical Engineers and the Institute of Metals might together influence education, training and qualifications in complementary areas.
Analysis of Screw-Expander Performance
Authors: Ng K C , Lim T B , Bong T Y
Published: February 2007

The paper examines the thermodynamic processes of a helical screw-expander that operates with dry saturated steam at its inlet. The work output of the screw-expander is analysed using a simple ‘pseudo-polytropic’ index. Using the available experimental data from the literature, an empirical model for the prediction of work using the ‘pseudo-polytropic’ indices is formulated. The expansion indices are expressed in terms of built-in volumetric and pressure ratios; how they are formulated is usually given in an expander specification. Based on the empirical model, there is a good agreement between the experimental work and the predicted values.
Buckling of Externally Pressurized Composite Torispherical Domes
Authors: Galletly G D , Muc A
Published: February 2007

The results of external pressure buckling tests on 0.25 m diameter woven composite (mainly CFRP) domes are given in the paper and they are compared with the predictions of the shell buckling program BOSOR 4. The agreement between theory and experiment was satisfactory. The tests also show that the buckling strength of CFRP torispheres is good. They could replace steel torispheres and would be considerably lighter.

The buckling pressures of the woven composite domes are a function of the Young modulus E but the relation is not a simple linear one (the in-plane shear modulus G12 also needs to be taken into account). Results of some tests on CFRP and GFRP domes lend support to this statement.

The provisions of BS 4994, when applied to these domes, predict that buckling is the controlling failure mode. While this is correct, the buckling pressures predicted by BS 4994 seem rather low.

The effect of dome thickness on the buckling pressures was expected to vary as (t/R)2. This was confirmed herein, to a limited extent, by a few tests on shallow CFRP domes.
New Approach to Determine the Heat+transfer Coefficients for Cooling Tower Packing
Authors: Younis M A
Published: February 2007

The heat input response technique was developed to determine the heat-transfer coefficients for a forced draught cooling tower packing. The method was applied to a counter current type air-water contact system in a packed bed. A temperature change was alternately imposed on inlet air at the tower bottom and on inlet water at the tower top. Outlet temperatures of air and water were measured with time. From zeroth moments of these temperature changes, water-film and air-film heat-transfer coefficients have been estimated. Finally, the effect of the water/air loading ratio and the packing material, such as wood, aluminium wire netting and plastic PVC on the values of the heat-transfer coefficients was experimentally tested. An empirical relationship between the gas-side heat-transfer coefficient, liquid-side heat-transfer coefficient and water/gas ratio has been established within the range of the tested data.
Inter-ring Buckling of Welded Ring-Stiffened Cylindrical Shells Subjected to External Pressure
Authors: Galletly G D , James S
Published: February 2007

Test results are given in the paper for six 0.6 m diameter welded steel cylinders, stiffened by external T-rings, which were subjected to external pressure. The radius-thickness ratio of the cylinders varied from 185 to 300 and the ratio of the length of the central bay of the cylinders to the radius varied from 0.28 to 0.60. In the assessment of the test results, three design codes were employed, viz. BS 5500, DASt 013 and ASME Code Case N-284.

The main aims of the tests were (a) to determine if the external pressure section of BS 5500 was too conservative in the ‘elastic’ range and (b) to ascertain whether the other two codes always gave safe predictions of buckling pressures.

On the basis of the tests discussed herein, it is concluded that, for externally stiffened cylinders, the reduction factor, α, in BS 5500 could be increased from 0.5 to 0.6 in the ‘elastic’ buckling region. Doing this would have commercial benefits but, before it is done, more tests need to be carried out in order to establish the repeatability of the present results. With regard to the DASt 013 code and ASME Code Case N-284, both of them predicted buckling pressures that were too high in several cases. These codes should be amended, particularly for cylinders which have geometric ratios similar to those tested herein. In connection with this point, the authors have been informed recently that DASt 013 will be replaced by DIN 18800, Part 4, some time in 1989. The buckling predictions of this new code, when applied to the six ring-stiffened models discussed herein, appear to be satisfactory.

Some recent German tests on short unstiffened cylinders are also reviewed and discussed from the viewpoints of the BS 5500, DASt 013 and ASME N-284 codes.
Breakdown and Recovery Equipment Modernization and Improved Techniques from New Technology
Authors: Robinson P J
Published: February 2007

Like many areas of engineering, changes in technology and working conditions have had a significant impact on breakdown and recovery equipment and techniques. Although breakdown cranes have hardly changed in concept for 100 years and innovations like hydraulic jacking equipment, when first established, was heavy and cumbersome, developments in materials and technology spurred on by the Health and Safety at Work Act and pressures to reduce costs in the 1970s have resulted in the introduction of a much wider range of equipment, which is lighter and easier to manage. This has reached a point where, for instance, only 15 per cent of incidents are now dealt with by cranes. This paper traces these changes over the last 15 years and shows how the current range of equipment available to recovery teams has developed.
Resilient Railpads: Their Dynamic Behaviour in the Laboratory and on Track
Authors: Grassie S L
Published: February 2007

Resilient railpads in a variety of materials and with different surface profiling have been tested in the laboratory and in track. A laboratory impact test based on that initially developed at the Battelle Columbus Laboratories provides a reliable ranking of the extent to which railpads attenuate dynamic strain in concrete sleepers in track. The test is also a good indication of the average attenuation provided by a pad in track. If dynamic loads in track are particularly severe the fractional attenuation provided by a pad is greater than that indicated by the laboratory impact test.

Laboratory resonance apparatus, in which the pad is the principal resilient element in a simple dynamic system, has been made to find the railpad's effective dynamic stiffness. There is good correlation between the stiffness measured in track and that measured in this apparatus.

A pad's dynamic stiffness is consistently at least as great as its tangent stiffness found from the static load/deflection curve. The load/deflection behaviour of a pad in track can be found from measurements in an assembly of rail and sleeper in the laboratory.
Supply-Side Harmonics in d.c. Supplied Drives: An Approach to Their Specification and Control
Authors: Goodman C J , Taufiq J A
Published: February 2007

The use of power electronic switching controllers for all types of traction drives can lead to harmonic currents on the supply side. These currents, by conductive or mutual coupling, can cause interference in signalling and telecommunications circuits. After reviewing these basic considerations, this paper outlines the harmonic spectra of d.c.-supplied chopper and inverter drives. In the case of chopper controllers, choosing a frequency unrelated to any signalling frequency combined with the attenuation provided by the input filter is usually sufficient to avoid dangerous interference.

For inverter drives, the situation is more complex due to the intrinsic sweep frequency nature of the drive. However, special modulation strategies can be used for the inverter which eliminates, or at least reduces to a safe level, any particular frequency which may interfere with signalling equipment. A method for generating these optimized pulse-width modulation schemes using fast on-board microprocessors is briefly described.
Procurement of Rolling Stock on the Hong Kong Mass Transit Railway
Authors: Donald W R , Gretton J R , Turner T D
Published: February 2007

This paper gives an account of the procurement of the electric multiple unit trains which have been manufactured and brought into service on the Mass Transit Railway in Hong Kong.

The paper outlines the Corporation's project management and control systems used on rolling stock contracts that have been let within the three major projects constructed over the period 1975–86; the modified initial system, Tsuen Wan extension and the Island Line, and examines the development of rolling stock equipment and procurement methods within these projects and in further contracts which are still to be completed.

Brief details of the railway system and parameters for design of the rolling stock are given and the paper reviews the planning, programming, forms of contract documents, tender procedures, financing methods and contract management techniques used by he Corporation in the rolling stock contracts.
Maintaining the Image
Authors: Zobel F G R
Published: February 2007

Exterior appearance of rolling stock is one factor which affects the passengers' perception of a rail service. The paper will describe the technology behind maintaining a good image, taking into account protective coatings and their application, liveries, soiling of surfaces and cleaning. Coatings must provide corrosion protection throughout the working life of the vehicle in an aggressive environment. This requires adequate treatment of many areas not seen by the passengers or, in many cases, by engineers during normal maintenance.