bluuebunny/crossref_metadata_2025 huggingface dataset:
The Role of the Discrete Fourier Transform in the Contribution to Gear Transmission Error Spectra from Tooth-Spacing Errors
Authors: Mark W D
Published: February 2007

An expression is derived for the Fourier series spectrum of the transmission error arising from tooth-spacing errors on a single spur gear meshing with a perfect involute mating gear for the case of a contact ratio of unity and no elastic deformations present. This expression is found to be in exact agreement with previously derived results. The expression illustrates the role of the discrete Fourier transform in transmission error analysis and interpretation.
A Parameter Sensitivity Analysis for the Dynamic Model of a Variable Displacement Axial Piston Pump
Authors: Kim S D , Cho H S , Lee C O
Published: February 2007

Sensitivity analysis is applied to an investigation of the influence of parameters on the dynamics of a variable displacement axial piston pump. Since an exact mathematical model of piston pump is complex and highly non-linear, the investigation of its dynamic characteristics for the variation of the system parameters by changing separate parameter values in sequence becomes very ineffective. In this paper a parameter sensitivity analysis was employed to analyse the effects of the system parameters systematically. The analysis was done on the exact non-linear dynamic model of the pump system which is represented by fourth-order dynamics. Based upon the simulation results, the degree of influence of each parameter and the justification of order reduction are discussed in some detail.
Using Programmable Controllers for Sequential Systems with Random Inputs
Authors: Pessen D W
Published: February 2007

A new method is presented for programming programmable controllers for random-input systems, in which the various input signals do not appear in any predefined order. The method is somewhat related to the well-known Huffman method for designing asynchronous sequential systems. However, while Huffman's method is limited to small problems, the method suggested here can be used with any number of input variables. Also, it is much easier to apply than Huffman's method, and does not involve filling in of Karnaugh maps. While the suggested method does not minimize the number of required relays, this does not represent a drawback where the solution is implemented with programmable controllers, since the number of relays available in even small programmable controllers is generally more than required.
Elastic Buckling of Internally Pressurized Cylinder—Bulkhead Combinations
Authors: Galletly G D , Blachut J
Published: February 2007

The shell structures considered in this note are unstiffened spherical caps attached to unstiffened cylindrical shells by means of circumferential stiffening rings. The loading is uniform internal pressure and the object of the analysis is to determine if elastic bifurcation buckling can occur and, if so, where the buckles will be located. The BOSOR 5 shell buckling program was used in the analysis and several stiffener geometries were investigated.

The present results show that elastic buckling can occur in the cylindrical portion of some cylinder—bulkhead combinations. If the structure is subjected to repeated loading, then the formation and disappearance of the elastic buckles could contribute to the initiation of fatigue cracks. Designers should, therefore, be aware of this possible elastic buckling mode. As some of the geometries investigated in the present note are not unlike some commercial aircraft configurations, the present results may be relevant to them also (even though those structures are stiffened).
Prediction of the Decay Process in Turbulent Swirl Flow
Authors: Algifri A H , Bhardwaj R K , Rao Y V N
Published: February 2007

Swirl flow in a pipe is studied experimentally and the data so obtained have been compared with theoretical predictions computed from a proposed calculation procedure which determines the swirl intensity, tangential and axial velocity distributions by defining only the flow parameters at the inlet of the test pipe.
Application of a Fast Self-Tuning Control Algorithm to a Hydraulic Test Rig
Authors: Daley S
Published: February 2007

The application of a fast self-tuning controller to a hydraulic test rig having a predominant natural frequency of the order of 20 Hz is described. The controller is shown to perform well despite the presence of non-linearities, measurement noise and load disturbances. Time-varying system parameters are rapidly compensated for and only minor transients are introduced by the tuning process. A method for assisting the selection of the parameters required for successful self-tuning controller implementation is also demonstrated.
Free Vibrations of Imperfect Cantilever Bars under Self-Weight Loading
Authors: Virgin L N
Published: February 2007

This brief study examines the relationship between the natural frequency of small oscillations and the length of vertical cantilever struts in a gravitational field. The analysis uses a Rayleigh approach and includes post-buckled equilibrium states and emphasizes the influence of initial imperfections.
Modal Balancing of Flexible Rotors during Operation: Design and Manual Operation of Balancing Head
Authors: Lee C-W , Kim Y-D
Published: February 2007

Modal balancing experiments are performed with a rotor bearing system by using a single wireless, manually controlled precision balancing head. The balancing head designed is proven to be accurately functioning, effective in modal balancing and reliable well over the first critical speed.
Buckling of Shallow Dished Ends under External Pressure—a Caveat
Authors: Galletly G D
Published: February 2007

The application of BS 5500 to the design of some shallow steel torispheres subjected to external pressure can result in safety factors which are lower than the expected 1.5. Some examples in which this occurs with elastic, perfectly plastic steels having yield points in the range 150 N/mm2 < σyp < 400 N/mm2 are given in the present note. Results are also given which show how the collapse pressures increase when linear strain hardening is included in the analysis.

For shallow aluminium torispheres, the Code rules seem safe but, since elastic buckling of the imperfect spherical cap may often be the controlling failure mode, the designs can be rather inefficient in the use of material.

Experiments on externally pressurized shallow torispheres having relatively low yield points are desirable in order to develop satisfactory buckling design rules for both the knuckle and the spherical cap regions of these dished ends.
Experiments on Laminar Flow about a Rotating Sphere in an Air Stream
Authors: El-Shaarawi M A I , Kemry M M , El-Bedeawi S A
Published: February 2007

Laminar flow about a rotating sphere which is subjected to a uniform stream of air in the direction of the axis of rotation is investigated experimentally. Measurements of the velocity components within the boundary layer and the separation angle were performed at a Reynolds number, Re, of 10 000 and Ta/Re 2 of 0, 1 and 5. These measurements are compared with the numerical solutions of the same problem where either theoretical potential or actual experimental boundary conditions are imposed on the governing equations.
Implementation of a Cavitation Algorithm into a Procedure for the Prediction of Non-Newtonian Flow in Hydrodynamic Journal Bearings
Authors: Williams P D , Symmons G R
Published: February 2007

A procedure for solving the Navier–Stokes equations for the steady, three-dimensional, cavitated flow of non-Newtonian liquids within finite-breadth journal bearings is described. The method uses a finite difference approach, together with a technique known as SIMPLE (Semi-Implicit Method for Pressure-Linked Equations) which has now become well established in the field of computational fluid dynamics. The concept of ‘effective viscosity’ to describe the non-linear dependence of shear stress on shear rate is used to predict the performance of bearings having a single axial inlet groove situated at the position of maximum clearance between the shaft and housing. The implementation of a cavitation algorithm into the equation set allows the loci of film rupture and reformation in the vicinity of the supply groove and elsewhere to be traced, these having a particularly important influence on the predicted lubricant flowrate.

Results are obtained for a range of non-linearity factors and lead to the conclusion that all the important indicators of bearing performance can be determined using the technique described.
London Underground Prototype Tube Trains
Authors: Aylward R W , Minter R H
Published: February 2007

As part of the overall programme for the renewal of the Central Line, London Underground is purchasing three prototype trains. These trains incorporate many new features and will form the basis for the next generation of tube rolling stock.

The trains are being bought on a main contractor basis and a complete specification was produced. The trains were ordered in May 1984 and are due for delivery this year. The major technical innovations of the trains are the use of large aluminium extrusions, solid state traction control, and materials with an improved fire performance.
Power Transmission Losses in V-Belt Drives Part 1: Mismatched Belt and Pulley Groove Wedge Angle Effects
Authors: Childs T H C , Cowbum D
Published: February 2007

AV 10 raw-edged V-belts cut to wedge angles from 32° to 42° have been run in 36° grooves on pulleys of 51 mm pitch circle radius. It has been shown experimentally that belts with wedge angles from 37° to 38.5° fitted the grooves best and were the most efficient. The excess speed and torque loss parts of the power loss of other belts was due to the larger radial compliance of these belts which did not fit their pulley groove. Current theoretical models of radial compliance of misfitting belts are shown to be wrong.

The results have been generalized and a theory of belt bending distortion developed to give detailed recommendations of the most efficient pulley groove angles in which to run belts cut to 40°, depending on pulley radius, belt construction and belt length.
British Rail Diesel Multiple Unit Replacement Programme
Authors: Shore A G L , Shore A G L
Published: February 2007

During the 1980s British Rail has been addressing itself to the problem of replacing its diesel multiple unit fleet. Initially two approaches of lightweight railbus and full weight diesel-electric multiple unit were tried and subsequently medium weight diesel-mechanical prototypes were evaluated.

The paper sets out the principal factors affecting the specification of each of the prototype units, the service experience gained with each type and the system studies and cost evaluations which were carried out.

All of this has taken place against a background of a constantly changing business requirement for the size of fleet, the duty and the sector of the market for which the units are intended.

The paper shows how these changed requirements have influenced, and are continuing to influence, the specification of the production fleet which is currently based on a mixture of medium and lightweight units.
Performance Evaluation of Motor Vehicle Active Suspension Systems
Authors: Hall B B , Gill K F
Published: February 2007

The essential features and potential of active suspensions are presented and selected systems are examined to relate the effects of closed-loop pole location to system performance. Results are compared with those for well-designed passive systems.
From sidecars to Silicon—a History of Innovation at Jaguar Cars
Authors: Randle J N
Published: February 2007

Reviews the history of the Jaguar Cars company from 1931 to 1986 with particular emphasis on the innovations in automotive engineering which have led to its successes. The decline of the company during the 1970s is outlined and the development work on the XJ40 undertaken in the 1980s, to ensure the survival of the company, is described.
Design Considerations of an Airborne Free Piston Compressor
Authors: Sher E
Published: February 2007

The effect of the atmospheric conditions on the performance of a spark ignition free piston engine has been investigated. A detailed computer code has been developed to simulate the unit cycle and was used to evaluate the effect of its geometrical proportions and the ambient conditions on the cycle performances. The model includes a semi-empirical model for the scavenging process, calculations of the flows into and out of the cylinders, empirical expressions for the combustion process and a practical approach for the heat transfer. The model has been calibrated by using experimental results of a conventional two-stroke engine having identical cylinder and port assemblies. It was concluded that the thermodynamic efficiency of the unit is strongly dependent on the receiver to the atmospheric pressure ratio, the compression ratio of the compressor, the compressor aspect ratio and the ambient pressure. It was shown that the thermodynamic efficiency varies insignificantly with the ambient temperature.
Compressible and Leaky Trains in Tunnels
Authors: Vardy A E , Fox J A
Published: February 2007

It is hypothesized that phase differences commonly observed between computed and measured pressure histories in railway tunnels may be caused in part by reduced acoustic wave speeds in the annular regions of flow alongside trains. Such reductions in wave speed are shown to be a possible consequence of the compressibility of trains and/or the leakage of air into and out of trains. These effects are shown to be capable in principle of reducing the effective wave speed by a factor of (1-β)1/2 where β denotes the train-tunnel area blockage ratio.

The potential influence of reduced wave speeds due to these causes is shown to be much greater in short tunnels than in long tunnels. An alternative explanation for the discrepancies observed in long tunnels has yet to be found.
Fire Protection on Trains
Authors: Dee A W
Published: February 2007

The hazards from fire in a moving vehicle are similar to the hazards from fire in a building and so similar steps must be taken to detect the presence of fire, to prevent it spreading and to extinguish it in this special circumstance.

This paper describes the diferent methods that can be used to provide an effective fire protection system from trains. The various system requirements are set out and a selection is made of the type of system required and the equipment needed to perform each task. Each element of the system, consisting of detection, control and monitoring and extinguishment, is dealt with separately and its advantages and disadvantages are given.

Finally, an assessment is made of the applications of the system, and reliability, testing, maintenance and safety features are discussed.
A Simplified Turbocharged Diesel Engine Model
Authors: Ford M P
Published: February 2007

A simplified model of a turbocharged marine diesel is developed which is suitable for stability studies of diesel electric generator systems.

By comparison with the manufacturer's detailed thermodynamic model, the simplified model was shown to have high steady state and transient accuracy over a wide load range.
A Study of Some Factors Affecting the Performance of a Contra-Rotating Axial Compressor Stage
Authors: Sharma P B , Jain Y P , Pundhir D S
Published: February 2007

An experimental investigation of the performance of a contra-rotating stage is reported. The influence of factors such as speed ratio of the two rotors, rotor stagger, pitch-chord ratio and axial spacing between the rotors is examined from tests on a 0.66 hub-tip ratio compressor. The study reveals that the performance of a contra-rotating stage is affected by all these factors. Axial spacing between the rotors and the speed ratio of the rotors both exhibit a strong influence on the stalling behaviour of the stage. It has been found that in a stage with close axial gap, rotating stall on the first rotor is suppressed if the second rotor is contra-rotated at a speed 50 per cent faster than the first rotor. This unique advantage of contra-rotation is not obtained if the axial gap is large. Measurements of sound pressure level are also reported to highlight the high noise problems associated with a contra-rotating stage.
Internal and Atmospheric Leakage Assessment and Intergate Overpressurization of Isolation Valves
Authors: Airey D R , Lung F K K , Metcalf M J , Salter S
Published: February 2007

Some problem areas which would lead to internal and atmospheric leakage in valves, specifically for pressurized water reactors, are identified. Frequent thermal transients can induce thermal stresses and promote the propagation of surface faults into the valve body and cause eventual cracking of the seat. Trapping of hard debris around the seat causes seat and disc damage as well as providing leak paths. Cavitation can also produce seat and disc damage, particularly in high-speed flows.

Atmospheric leakage is caused mainly by the deficiencies in gland packings and by overpressurization problems in valves. In the case of bellows and diaphragm sealed valves, metal fatigue, stress corrosion cracking and punctures are the usual cause. The overpressurization problem in valves can increase the rate of gland deterioration. The problem is discussed in some detail in this paper. Analysis of theoretical gland packing results suggest that stem friction reduction and discarding lantern rings in stuffing boxes can improve the sealing performance of the packings. Ideally the sealing material should have a low coefficient of friction and a high Poisson ratio.
Stability Analysis of a Load-Sensing Hydraulic System
Authors: Kim S D , Cho H S , Lee C O
Published: February 2007

The load-sensing hydraulic system is an energy saving hydraulic system which improves the efficiency of transmitting power from the pump to the load. However, its stability characteristics deteriorate critically due to the addition of the load-sensing mechanism, compared with those of the conventional system. In this paper, a non-linear mathematical model of the load-sensing hydraulic system is formulated, taking into consideration the dynamics of the load-sensing pump. Based upon linearization of this model for various operating conditions, the stability analysis has been made using the Routh-Hurwitz stability criterion. The results of the theoretical stability analysis were assured through experiments. Both results show that stability is critical to the choice of system parameters such as the setting pressure of the pump compensator and the load inertia.
Momentum Analysis for a Cascade of Flat Plates in Supercavitating Flow
Authors: Fry S A
Published: February 2007

The forces exerted upon a cascade of hydrofoils in supercavitating flow are analysed by considering momentum changes in the flow between stations upstream and downstream of the cascade. Unlike potential flow models the momentum model takes account of turbulent mixing of the wake with the outer flow (as occurs in real flow) and it is possible to calculate the resulting energy losses. Unfortunately, however, this global approach does not permit cavity lengths to be estimated. A semi-empirical theory is developed which allows lift and drag force cavitation characteristics to be calculated for flat plate cascades. Experimental results are compared with theoretical predictions from the momentum theory and from both linear and non-linear potential flow theories.
Computational Method to Assess Concentration of Water in Crude Oil Downstream of a Mixing Section
Authors: Baker Roger C
Published: February 2007

This paper describes a method for predicting the concentration distribution of water in crude oil in a pipe section downstream of a region of mixing and droplet break-up.

The complexity of the problem and the necessary simplifications are described. The method with its approximations is justified on grounds of possible savings in financial outlay.

Details of governing equations, computational method and boundary conditions lead on to the link between forces on the droplet and the velocity of the droplet relative to the bulk liquid. The model incorporates turbulence enhancement and decay, and secondary velocities likely to approximate to those following a T-piece or bend or swirl-creating element.

The computer program was tested against data provided by BP and the results suggest that if the predictions indicate adequate mixing then they are likely to underestimate the uniformity of the mixture.

The predictions may be used to assess the suitability for sampling based on Case 1 of the draft ISO Standard (1) but must not be used to assess the suitability for sampling based on Case 2 of the draft standard unless fall-out has been allowed for in the program.

The paper reviews the assumptions and approximations involved in this model. Further work in these areas is needed to allow the model to be used with greater confidence.
The Pursuit and Achievement of Engineering Excellence
Authors: Grinsted Noel
Published: February 2007

Major achievements in industry have generally focused on a single major project. This paper attempts to show that the ‘pursuit of engineering excellence’ has been adopted more widely in recent years. It comments on the changes in the performance of British industry and suggests a variety of achievements in terms of changing attitudes, methodologies and management styles. The role of consultants in the current economic and industrial climate is discussed and the concepts of ‘performance audit’ and ‘plant enhancement’ are outlined. The paper concludes by describing two specific applications of these techniques in manufacturing industry.
The Influence of Diffuser Channel Length-Width Ratio on the Efficiency of a Centrifugal Compressor
Authors: Clements W W , Artt D W
Published: February 2007

A series of experiments was carried out on a turbocharger compressor aimed at determining the optimum diffuser channel length-width ratio. It was found that increasing the length-width ratio beyond 3.7 did not result in any performance improvements. It was also shown that a short channel coupled with a downstream vaneless diffuser could yield equal pressure recovery to a channel diffuser of equal outside diameter.
The Failure of Two Torispherical Shells under Internal Pressure
Authors: Blackler M J , Ansourian P
Published: February 2007

Two welded stainless steel tanks incorporating spherical end caps, torispherical knuckles and cylindrical body are tested to failure under internal pressure loading. One tank is of a traditional crown and segment construction and has a relatively high level of imperfection. The other tank has fewer circumferential welds at the knuckle and has a smaller level of imperfection. The pressure for first yield at the knuckle is well below predictions of first-order theory; better agreement exists when the measured geometry is input to the analysis and large displacement theory is used. Failure is by elastic-plastic buckling at the knuckle, and in each case, a reduced postbuckling pressure is easily maintained. Most but not all buckles occur at meridional weld lines. Good agreement is observed with a recent proposal for the prevention of premature buckling in torispherical vessels.
Pipework Refurbishment
Authors: Ford A M , Attard M A , Donaldson I R
Published: February 2007

The refurbishment of pipework can place unusual and varied demands on a contractor. This paper illustrates some of the engineering aspects associated with two such case histories. The recommendations that were made and implemented for the reinstatement of these piping systems are outlined. General recommendations of techniques that may be adopted when refurbishing damaged pipework are also presented.
The Efficiency of Roots Compressors and Compressors with Fixed Internal Compression
Authors: Stone C R
Published: February 2007

It is well known that compressors, such as the Roots compressor, with no internal compression have a low efficiency. Two approaches (1, 2) to the efficiency analysis are compared here, and the correct approach is identified. The results for the efficiency of ideal systems are placed in context by considering typical applications, along with methods for improving the efficiency. The significance of the internal leakage losses reported elsewhere is established and comparisons are made with the inherent thermodynamic losses. The analysis is extended to cover compressors with some internal compression, such as sliding vane and screw compressors, when they are operating away from their design point.
A Model for Combustion Losses in a Pulverized Fuel Fired Power Plant Boiler
Authors: Krishna V , Sharma P B
Published: February 2007

A model for the estimation of combustion losses in a pulverized fuel power plant boiler is presented. The model is based on the formulation of a probability density function which relates the probability of a fuel particle remaining unburnt to the combustion and resident times. An empirical model is also presented which relates the unburnt carbon loss to average particle size and excess air. The two models are shown to be in close agreement with each other. The models are validated from the experiments on a power plant boiler.

The dependence of boiler efficiency on particle size and excess air is also examined and an empirical correlation between optimum excess air and particle size is derived. The mechanism of two-way coupling between boiler and turbine side parameters is also illustrated. It has been shown that the optimum excess air levels for maxima in plant heat rate and boiler efficiency are not the same, since the two-way coupling influences both the turbine heat rate and boiler efficiency. The effect of two-way coupling has been found to be more predominant for particle sizes of the order of 200 μm.
Technology, Economic Growth and the Professional Engineer
Authors: Roith Oscar
Published: February 2007

The President describes the relationship between technology and the prosperity of our society, and outlines the essential role of the engineer in contributing to this prosperity. He reviews his career in industry and Government and the key contribution of engineering to the growth, development and commercial success of the oil and petrochemical industry. By means of some case studies he illustrates the role of the mechanical engineer in a process industry.
Knowledge Representation Database for the Development of a Fixture Design Expert System
Authors: Darvishi A R , Gill K F
Published: February 2007

To meet the demands of the flexible manufacturing system, an exploratory approach to the design of fixtures using an expert system is presented. A small part of the range of knowledge existing is utilized to create a database framework that can be used to develop a computerized approach to fixture design.

The method allows for an expansion to a relatively large database that, when established, would encompass all of the important practical aspects of fixture design.
Modelling of Electrohydraulic Systems with Transmission Lines using Modal Approximations
Authors: Watton J
Published: February 2007

The method of modal approximation to the distributed friction transmission line functions via frequency-domain analysis is briefly discussed. A specific form is then derived which allows time-domain analysis to be easily pursued using a digital simulation package approach. The method is applied to a highly non-linear servo-valve controlled motor system and a good comparison between experiment and theory is shown. A comparison is also made with previous work using the method of characteristics, and natural frequency predictions are also compared with some common lumped parameter approximations.
Mechanical Handling Engineers—A Case for Engineering Management with Style
Authors: Batley T W
Published: February 2007

This case study concerns a mechanical engineer who has strong views on business management. He purchased a small engineering company in Dunedin, New Zealand, and put into practice his managerial philosophies of worker participation in decision-making and profit-sharing. The paper reviews the progress of the company during its first three years and then discusses the options for its future development.
Supplier Quality Assurance Systems: A Study in the Nuclear Industry
Authors: Singer A J , Churchill G F , Dale B G
Published: February 2007

This paper reports the results of a study which investigated the impact of quality assurance on 13 suppliers to the nuclear industry. The purpose of the study was to determine the benefits and problems of applying quality assurance in the supply of high risk plant items and material for nuclear installations. The paper discusses the problems facing the industry including: multiple audits and inspections, the irritation with having to contend with two quality system standards (namely BS 5750 and BS 5882) and the cost effectiveness of the more stringent quality system and quality control surveillance requirements imposed by the nuclear industry. It is also pointed out that companies supplying non-nuclear industrial customers were dissatisfied with the qualifications, experience and professional competence of some auditors and many inspectors.
Leakage Flow Detection in a Fluid Power Speed Control System Using a Personal-Computer-Based Condition Monitoring Package
Authors: Watton J , Creber D J
Published: February 2007

A relatively low-cost personal-computer-based system is used to condition monitor a servo-valve-motor speed control system. Line pressures-flowrates together with motor torque-speed are monitored via 12 bit analogue to digital converters, and a set of performance characteristics are transformed into a mathematical model for the system in its run-in condition. Leakage flows are then introduced from each line, to simulate the onset of failure, and across the lines to simulate motor cross-port leakage deterioration. A graphics and software package is then developed and used to indicate which of the faults is occurring.
A Non-Contact Opto-Electronic Sensing Device for Precision Linear and Angular Positioning of Robotic Manipulators
Authors: Shams I , Rahnejat H , Greening D
Published: February 2007

A non-contacting optical sensor is devised to monitor the position and orientation of a robot end-effector or grasped object within fine limits of accuracy. This enables fine alignment of tools or parts with respect to assembly fixtures, thus rendering precision assembly tasks to be performed in a dexterous manner. The sensor is capable of detecting linear displacements of the order of 5 μm or better and angular misalignments down to 5 seconds of arc. The principle of differential detection is employed which reduces the undesired effects of noise and fluctuations in the source intensity.
Expressions for Secondary Streamwise Vorticity Which Allow for Streamwise Losses
Authors: James P W
Published: February 2007

In this paper it is shown how the analysis of Came and Marsh ( 1) can be extended to provide estimates of secondary streamwise vorticity at the exit of a blade-row when the primary flow includes streamwise losses and takes place on rotating axisymmetric streamsurfaces. The results are shown to be consistent with those of Smith ( 2) under suitable limiting conditions.
Aspects of Fatigue Crack Growth
Authors: Brown M W
Published: February 2007

The propagation of fatigue cracks under low levels of cyclic stress can be modelled by linear elastic fracture mechanics. Elastic-plastic parameters must be used for the higher stress amplitudes of conventional S–N curves in both the low and the high cycle fatigue regimes. The occurrence of different modes of crack growth is discussed and the use of a propagation law to predict component lifetime is demonstrated.
Three-Dimensional Thermoelastohydrodynamic Analysis of Pivoted Pad Thrust Bearings Part 2: Application of Theory and Comparison with Experiments
Authors: El-Saie Y M H Ali , Fenner R T
Published: February 2007

In Part 1, a computational method was described for predicting the performance of pivoted pad thrust bearings. In this second part, computed results are compared with experimental data. Three test cases are considered, which cover the range of bearing sizes normally encountered in practice, from a 150 mm diameter laboratory scale experiment through the main propulsion thrust bearings of a destroyer to a 3 m diameter bearing. Generally good agreement is obtained for both temperatures and film thicknesses.
Minimum Film Thicknesses in Lubricated Point Contacts Operating in the Elastic Piezoviscous Regime
Authors: Hooke C J
Published: February 2007

Previous attempts to derive equations for the minimum film thickness in the elastic piezoviscous regime have relied upon extrapolations from numerical results. This paper describes an alternative approach in which the characteristics of heavily loaded contacts are exploited to obtain general expressions, firstly, for the central region and secondly, for the side lobes that may form at the ends of the contact. It is shown that the clearances in these two regions behave differently. The elastic piezoviscous regime must, therefore, be divided into two sub-regimes. Expressions for minimum clearance are presentedfor each.
Theoretical Road Damage Due to Dynamic Tyre Forces of Heavy Vehicles Part 2: Simulated Damage Caused by a Tandem-Axle Vehicle
Authors: Cebon D
Published: February 2007

The literature relating to road surface failure and design is briefly reviewed and the conventional methods for assessing the road damaging effects of dynamic tyre forces are examined. A new time domain technique for analysing dynamic tyre forces and four associated road damage criteria are presented. The tyre force criteria are used to examine the road damaging characteristics of a simple tandem-axle vehicle model for a range of speed and road roughness conditions.

It is concluded that for the proposed criteria, the theoretical service life of road surfaces that are prone to fatigue failure may be reduced significantly by the dynamic component of wheel forces. The damage done to approximately five per cent of the road surface area during the passage of a theoretical model vehicle at typical highway speeds may be increased by as much as four times.
Travelling Wave Control of Rotating Discs and Analysis of its Spillover Effect
Authors: Kim C-S , Lee C-W
Published: February 2007

A modal control scheme for rotating disc systems is developed based upon the finite-dimensional sub-system model including a few lower backward travelling waves important to the disc response. For the single discrete sensor and actuator system, a polynomial equation, which determines the closed-loop system poles, is derived and the spillover effect is analysed, providing a sufficient condition for stability. Finally, simulation studies are performed to show the effectiveness of the travelling wave control scheme proposed.
The Effect of Pressure Gradient and Freestream Turbulence Intensity on the Length of Transitional Boundary Layers
Authors: Fraser C J , Milne J S , Gardiner ID
Published: February 2007

The paper presents the results of an experimental investigation aimed at an elucidation of the individual and collective influence of freestream turbulence intensity and pressure gradient on the length of the transitional boundary layer. A correlation for the transition length Reynolds number is developed and used, in an intermittency-based computational scheme, to predict the transitional boundary layer behaviour in a number of practical flows representative of the suction surface of gas turbine blading.
The Effect of Thermal Distortion on the Characteristics of Large Hydrodynamic Bearings
Authors: Morton P G , Johnson J H , Wale G D
Published: February 2007

An experimental investigation has been carried out on a 350 mm partial arc journal bearing to determine the steady state characteristics and the stiffness and damping coefficients. The bearing was found to distort due to thermal influences and the pressure distribution and dynamic coefficients consequently differed markedly from those obtained using standard theoretical techniques. Calculations of the speed at which resonant oil whirl develops in a rotor supported by bearings of this type show that the threshold speed is far higher using experimental coefficients than theoretical coefficients. It is concluded that thermal distortion has a significant stabilizing effect on large hydrodynamic bearings.
The Lubrication of Overclamped Slippers in Axial Piston Pumps—Centrally Loaded Behaviour
Authors: Hooke C J , Li K Y
Published: February 2007

In overclamped axial piston pump slippers only part of the clamping load is carried by the hydrostatic pressures. The remainder has to be supported hydrodynamically and small amounts of non-flatness of the slipper surface are essential for successful operation. It is shown that, under centrally loaded conditions, the operating clearance does not vary greatly with the magnitude or profile of the surface non-flatness, provided that the surface is generally convex. Thus the film thickness under the slipper can be predicted with reasonable accuracy. Measured clearances closely match those calculated theoretically.
The Response of Distributed—Lumped Parameter Systems
Authors: Whalley R
Published: February 2007

Physical systems are constructed from a variety of components, some of which have relatively concentrated, pointwise features while others have spatially distributed characteristics. In contrast, models rarely reflect this structure, thereby avoiding the mathematical difficulties arising from the manipulation of sets of mixed algebraic, ordinary and partial differential equations which may generate irrational functions on transformation. In this paper general results are produced, enabling the response to systems comprising a series of distributed-lumped elements to be calculated. A simple example is included to illustrate the procedures outlined.
The Design and Initial Testing of a Prototype Stirling Cycle Heat Pump
Authors: Rix D H
Published: February 2007

This paper covers the first step of an investigation into the potential of the Stirling cycle heat pump. The design and construction of a prototype is described. Particular reference is made to the use of a previously developed theoretical model in the design optimization of the heat exchangers and regenerator. The resultant machine has been tested over a wide range of heat delivery temperatures and temperature lifts, using a pair of hot oil circuits to exchange heat with.

Though these initial tests have revealed two design flaws, which have seriously reduced the values attained for the coefficient of performance, they have demonstrated the ability of the Stirling cycle heat pump to deliver heat at higher temperatures and over larger temperature lifts than established types of heat pump.
A Hybrid Internal Combustion Engine/Battery Electric Passenger Car for Petroleum Displacement
Authors: Foster I , Bumby J R
Published: February 2007

This paper examines the potential of the hybrid electric vehicle in substituting petroleum fuel by broad-based electrical energy. In particular a hybrid car is considered. The way in which the powertrain can be controlled and the effect component ratings have on achieving the petroleum substitution objective are described. It is shown that a hybrid vehicle can be designed that can achieve a petroleum substitution of between 20 and 70 per cent of the equivalent internal combustion engine vehicle, be capable of entering environmentally sensitive areas and yet be capable of a range at high and intermediate speeds that is limited only by the size of its fuel tank.
The Changing Research and Development Role in the Mobility Industry from a Supplier's Point of View
Authors: Coleman W S
Published: February 2007

Many changes are occurring in the transportation equipment industry and some changes are being made at an accelerating rate. Global competition has spawned mergers, acquisitions, joint ventures and ‘partnerships’ which are changing the traditional roles played by vehicle builders and their component and material suppliers.

In some cases the OEMs are moving toward more reliance on ‘full service’ suppliers who can provide ‘cradle to grave’ support. This implies that a longer-term relationship must be established (and earlier) in the new product development cycles with a clearer under standing of the business needs of both parties.

Product R and D and planning must be brought together with both suppliers and the OEMs participating in development programmes that will result in shorter response times, less ‘total’ programme and product costs, and much better downstream quality.
Optimizing Proportions of Railway Brake Discs by Temperature Transients Evaluation
Authors: Missori S , Sili A
Published: February 2007

When evaluating the performances of railway brake discs, the ability to accumulate and spread heat to the air plays a major role, since wear of synthetic lining and disc deterioration are strongly dependent on maximum temperatures attained on the surface in contact with the friction pad.

The energy developed during brake application gives rise to an increase of disc temperature, which can be correlated to braking power, braking sequences and durations and to disc features. Maximum temperatures are attained on the friction surface of the disc. Determination of the thermal cycle subsequent to brake application can be considered preliminary to the study of lining and disc wear.

The present work proposes a simple method using finite difference numerical analysis to evaluate the efficiency of the brake disc in dissipating the heat, both on a constant speed and an up-to-stop brake application. The effect of the various dimensional parameters, such as number of ribs, disc thickness and ribs width, is considered with the aim of achieving a first rough optimization of the required size of disc brake. The results related to a commercial size disc brake are given.
Impact and Movement of Pedestrians in Frontal Collisions with Vehicles
Authors: Wood D P
Published: February 2007

The movement of pedestrians after frontal impact with vehicles and the inter-relationship between pedestrian throw distance and the pre-impact velocity of the vehicle is of interest in accident reconstruction.

This paper derives a single-segment rigid-body model for the primary and secondary impacts between the pedestrian and the vehicle. Published data on staged collisions involving horizontal flight are used to derive pedestrian-ground friction coefficients and show that the friction coefficient decreases with increasing speed. The analysis shows that for horizontal flight the throw distances of adults and children are similar.

For impacts with cars the model for primary and secondary impact yields calculated throw distances that closely match published results for staged collisions between cars and dummies and cadavers.
Switch-On Delays in Multiplexed Automotive Brake Lamps
Authors: Greaves A , Hampshire M J
Published: February 2007

The purpose of this report is to outline some of the facts associated with automotive brake lamps so that a well-informed decision may be taken as to whether or not they are suitable for inclusion in a multiplex system.

For background data, driver reaction time is defined and quantified at around 700 ms, with individuals tested falling in the range 280 ms-2 s.

The rate at which a hard-wired brake lamp bulb increases its luminance is then examined; this is found to depend largely upon the impedance of the wiring that connects the bulb to the battery. A minimum level of intensity that the bulb must reach is decided upon (297 lm), and it is found that the hard-wired bulb takes between 105 ms (Rline=250 mΩ) and 135 ms (Rline=500 mΩ) to reach this level.

A similar experiment carried out using the bulb driven by a multiplex system found it now took between 108 and 120 ms to reach the same level.

The conclusion is that for the system tested there can be no justification for not multiplexing the brake lamp circuit on the grounds of system latency.
High-Cycle Fatigue of Shafts due to Starting Transients in Drive Systems
Authors: Velonias S G , Aspragathos N A
Published: February 2007

This paper investigates some of the effects that structural characteristics and main non-linearities of a drive system have on systems response and its shaft fatigue.

In the suggested approach a general drive system, including a motor, load and speed reducers, is modelled as a multi-degree-of-freedom torsional vibrations non-linear system. The differential equations of the system are formed automatically. The user of the developed program must input just the constants of the components. An algorithm to compute the loss of life of the shafts due to fatigue is also incorporated into the program.

As an example, a drive system, including a motor, a speed reducer and load is modelled and tested under starting conditions. The effects of changing spring constants of the shafts and the backlash of the speed reducer are investigated.
Engine Friction—A Change in Emphasis
Authors: Monaghan M L
Published: February 2007

This paper reviews the evaluation of experimental methods for determining friction in engines. The latest techniques permit the investigator to examine changes of tribological behaviour in the engine. The use of these newer methods to improve conventional engines by design changes and to facilitate the introduction of novel materials is discussed.
Technical Considerations for Catalysts for the European Market
Authors: Gandhi H S
Published: February 2007

The durability of automotive catalysts for European applications were investigated as a function of higher temperatures encountered in autobahn driving over extended periods of time, potentially higher lead levels anticipated in the beginning in European unleaded fuels and occasional misfuelling with leaded fuels. Increasing residual lead levels from 3 mg Pb/L to 10 mg Pb/L in laboratory experiments at 1000°C peak temperature substantially decreased three-way catalyst (TWC) performance. Higher temperature ageing conditions from 730 to 1000°C resulted in 50 per cent loss of BET area and increased stoichiometric light-off temperatures.

The paper also reviews briefly the role of noble metals, rare earth oxides and base metal oxides in the formulation of practical TWCs. The operation of a TWC and the effects of A/F modulation frequency and amplitude on its performance are also discussed.

Important thermal and chemical modes of TWC deactivation are discussed with specific examples. The importance of matching the active metal component to the support material to achieve the desired metal-support interactions and how this understanding has led to the development of practical TWC with proper utilization of noble metals is emphasized.

Finally, the lean-burn versus stoichiometric combustion approach as it relates to catalyst requirements is also discussed.
A Technique for the Accurate Measurement of Low Values of Rolling Resistance
Authors: Frank T G , Abel E W
Published: February 2007

This paper describes a method of measuring rolling resistance for vehicles with relatively high mass and low rolling resistance. The technique, in which the deceleration of a test vehicle is measured, overcomes some of the problems of other methods and allows a wide variety of surfaces to be used. Computerization is used for automatic timing and data processing. The implications of surface flatness and instrumental accuracy are discussed and the analysis of an experimental investigation shows that accuracies to within 3 per cent are possible.
Computer Modelling of Temperature Distribution in Brake Drums for Fade Assessment
Authors: Rao V T V S Ramachandra , Ramasubramanian H , Seetharamu K N
Published: February 2007

Simulation of the temperature distribution in a brake drum of a commercial truck is carried out using the finite element method. Verification of the predicted values is done using an inertia dynamometer with a data logging system. The effect of variable convective heat-transfer coefficient and the effect of contact area are also studied. From the investigation it is concluded that the present model can be used for the simulation of temperature distribution in rigid brake drums during a fade test.