bluuebunny/crossref_metadata_2025 huggingface dataset:
Friction in Femoral Prosthesis and Photoelastic Model Cone Taper Joints
Authors: Fessler H , Fricker† D C
Published: February 2007

Static axial push-on and lift-off, and push-on and twist-off experiments were designed and performed to measure the effective, room-temperature coefficient of friction μ for different design femoral prosthesis cone taper joints comprising a universal head on a stem spigot. Alumina and metal heads were tested on metal spigots using either distilled water, Ringer's solution, blood or no lubricant. Complementary push-on and lift-off friction tests of Araldite model joints for subsequent frozen-stress, photoelastic stress analysis were performed at 130°C.

It was found that lubricant caused little decrease in the values of the coeficient of friction in prosthesis tapers. The values measured were typically μ =0.2 for an alumina head on a Co-Cr-Mo or Ti-6Al-4V spigot, μ = 0.15 for a Co-Cr-Mo head on a Co-Cr-Mo or Ti-6Al-4V spigot and μ =0.13 for a stainless steel head on a stainless steel spigot. For Araldite photoelastic models of an alumina head on a Vitallium spigot, as-cast taper surfaces lubricated with silicone grease gave consistent friction of typically μ = 0.14. The axial displacements of model heads on their spigots were compared with predicted values and previously measured values for prosthesis heads.
A Study of Stresses in Alumina Universal Heads of Femoral Prostheses
Authors: Fessler H , Fricker† D C
Published: February 2007

Three-dimensional, frozen-stress photoelasticity was used to study the best shape for a proposed alumina universal head loaded on to a Vitallium cone taper spigot with a 30° inclined force, as in vivo. Typical cone taper friction values were reproduced in the photoelastic models.

The location of the highest tensile stresses in the Mark I shape with a flat crown was found to be on the inner surface of the crown. Changing to a torispherical surface in the Mark II shape reduced this magnitude. However, the Mark III shape with a hemispherical inner crown surface gave even lower stress there, equal to the maximum value of the hoop stress at the taper, which was measured to be fairly uniform both around and along the taper except at the ends where contact pressure concentrations were found to occur and it became reduced.

Lamé axisymmetric cylinder stress predictions were found to be useful approximations to measured values and were generally overestimates of the tensile hoop stress at the head taper surface.
Electricity—Some Views on the Selection of Plant for the Next Generation of Power Stations
Authors: Masding H
Published: February 2007

This paper reviews some of the factors influencing the selection of thermal generating plant for installation in the next generation of power stations in England and Wales. The effect of the variations in the demand for electricity throughout the day and the seasons is considered in brief outline and it is concluded that the power system will be best served by the installation of large high-efficiency plant to cover the base load on the system supplemented by smaller, cheaper flexible plant for part load and two shift operation. After a brief introduction the paper is set out under the following headings:

Consumers' needs and the existing system Load growth and plant replacement General considerations Machine design and commercial strategy

Concluding remarks

The views expressed in this paper are the personal views of the author and are not influenced by any organization. Some of the current proposals are disputed and the object is to promote further discussion in order to lead to the unqualified establishment of the best policy for both the utility and the power plant industries for application at home and overseas.
Co-Generation Energy Centres in Diverse Production Facilities
Authors: Phillips A L , Pearson A
Published: February 2007

This paper gives a review of applications within the Unilever Group, including plants in operation and studies that did not result in implementation, discusses the development of Unilever's Mersey side site and gives a review of Unilever's recently completed remodelling of the Merseyside Power Station, Port Sunlight, including the financial case, how it is put into practice and operating experience.

The oil-fired high-pressure boilers/backpressure steam turbines station now incorporates a 105 tonne/h, 103 bar, 510°C, spreader stoker coal-fired boiler and a 9.5 MWe heavy fuel oil-burning medium-speed diesel engine. Both operate on ‘base load’. The station is flexibly integrated by means of feedwater and air heating systems.
The Differentiation of Loose and Secure Femoral Implants in Total Hip Replacement Using a Vibrational Technique: An Anatomical and Pilot Clinical Study
Authors: Rosenstein A D , McCoy G F , Bulstrode C J , McLardy-Smith P D , Cunningham J L , Turner-Smith A R
Published: February 2007

Anatomical study: The common pathway to failure in total hip replacements is loosening of the acetabular and femoral components. The reliable diagnosis of this loosening is difficult. A non-invasive technique has been developed which analyses a vibration signal transmitted through the femur. This can distinguish between a femoral component which is loose and one which is firmly fixed. Charnley femoral components were cemented securely into ten cadaver femurs and the transmitted vibration signal recorded. The prostheses were then loosened first at the cement-prosthesis and then at the cement-bone interface. The tests were then repeated. Consistent and distinct differences between output vibration signals were observed between the firmly implanted and the loose prostheses.

Pilot clinical study: Seven patients admitted for recision surgery because of clinical and radiological evidence of femoral implant loosening were tested using this technique. A further four patients with secure femoral components were tested approximately two weeks after total hip replacement. The differences in output signal, which had been observed between firmly implanted and loose prostheses during the anatomical study, were again demonstrated.
A Study of the Cracking Sounds from the Metacarpophalangeal Joint
Authors: Watson P , Kernohan W G , Möllan R A B
Published: February 2007

The familiar cracking sounds produced by distraction of the metacarpophalangeal joints were studied using accelerometers and a computerized signal analysis system. The joints were distracted in a controlled manner using a motorized device which simultaneously monitored the load on the joint and its extension. The load and extension parameters and those from the signal analysis were used to examine diurnal variation, the effects of multiple distractions, distraction speed, hand temperature and loading between distractions, and to show that in many cases, the energy contained in a crack signal, expressed as a ratio of the articular cartilage volume, exceeded a known level needed to produce articular cartilage damage.
Fan Blade Selection for Low Noise Part 1: Design Philosophy
Authors: Hay N , Mather J S B , Metcalfe R
Published: February 2007

It has been known for many years that the broadband noise of rotating machinery is dependent on the condition of the boundary layers on the lifting surfaces. Designs with high efficiencies and clean flow have mainly produced low noise levels. These units have generally used high technology blading, with low inlet velocities and minimal separated flow.

In the application of machines in industry, however, many are subject to inlet flow distortion and turbulence. These produce changes to the flow pattern around the blades which may have a relatively insignificant effect on the aerodynamics of the machine but almost completely destroy its acoustic performance.

The design method described by Hay, Metcalfe and Reizes (15) allows the designer to pitch the operating point well away from stall.

Thus low-response blading can be used for those installations whose flow conditions cannot be improved.

This method is further developed in this paper using some correlations from McKenzie's work (17).

The application of the method to the design of a low noise fan in the presence of a ±10 per cent perturbation on inlet velocity is given in way of illustration of the approach.

In Part 2 of this paper (to be published later) it is hoped to demonstrate the validity of the design philosophy presented here with test results from fans designed according to this philosophy.
The Fort Dunlop Combined Heat and Power Plant
Authors: Price M E , Chilton M D
Published: February 2007

The paper describes the combination of a large medium-speed diesel engine with a conventional chain grate boiler at the Fort Dunlop combined heat and power (CHP) station. The CHP station is situated in Birmingham, England, and is owned and operated by the Midlands Electricity Board (MEB).

A detailed description of the plant is given including the combination of both the water and gas systems.
Occupational Hot Exposures: Body Physiology and An Approach to Numerical Assessment
Authors: McLean R C , Galbraith G H , Stewart D
Published: February 2007

This paper summarizes the factors which influence the energy exchange processes between an individual and his surroundings and the mechanisms by which the body attempts to maintain itself in a heat balance situation. Thereafter, the important physiological reactions to hot working conditions are described and, on this basis, a numerical assessment procedure is proposed. Examples are given of the use of this method in investigating the possibility of heat stress and estimating the time for which an acclimatized worker can safely be exposed in such circumstances. An increase in the permissible exposure time through a manipulation of the environmental parameters is also considered.
Three-Dimensional Analysis of Closed-Die Forging Processes Part 2: Applications
Authors: Lugora C F , Bramley A N
Published: February 2007

A generalized procedure for the analysis of three-dimensional forging problems has been proposed using the upper bound elemental technique. This analysis allows the subdivision of a forging into elementary simple regions. In this second part of the series, the model is applied to predict forging load in a selected category of closed-die forging processes. Experiments are carried out and a reasonable agreement with theory is found.
Space Sled—a Device for the Investigation of the Physiological Effects of Weightlessness
Authors: Harry N A J , Benson A J
Published: February 2007

Space Sled is a device for providing controlled linear acceleration stimuli in the microgravity environment of orbital flight. The scientific objectives of the experiments which used Space Sled on the D-1 Spacelab mission were to study aspects of otolith organ (that is, that part of the inner ear which transduces linear accelerations) function and adaptation in weightlessness. Space Sled comprises electrical and mechanical sub-systems. The latter is made up of a carriage running on twin rails that are fixed to the floor of Spacelab. The assembly is 6 m long with a working section of 3.5 m. The seat accommodating the test subject can be mounted on the carriage in any of three orthogonal positions. The carriage is coupled by a flexible steel cable to a servo-controlled electric motor which is capable of producing a peak acceleration of 2 m/s2 and peak velocity of 2.4 m/s. In the event of failure of comprehensive safety circuits in the electrical sub-system, a mechanical snubber, of crushable honeycomb construction, limits the deceleration to 20 m/s2. Mechanical structures providing carriage guidance, Sled/Spacelab interfaces, carriage latching, motor mounting and cable tensioning are detailed in the paper.
Engineering for Competitive Advantage
Authors: Watson P , Pullen J
Published: February 2007

The focus of competition in manufacturing industry has shifted from cost to technology. But competitive advantage based on technology can only be maintained by a policy of continuous renewal and innovation. There are never enough new products and their development is never fast enough. To recoup the heavy investment of resources demanded by the increasing pace and complexity of new product developments they must be exploited in the broadest possible marketplace. The paper discusses the sourcing, selection and development of innovative product ideas from the standpoint of an international automotive component supplier.
Small Arms Manufacturing for the 1990s
Authors: Summerfield P H
Published: February 2007

When British Aerospace acquired Royal Ordnance in 1987 it was midway through the first phase of a fixed-price contract to supply rifles to the Ministry of Defence (MOD), its single biggest customer, and had a firm option on the second phase. However, there was a significant problem in that each new British Army rifle was incurring a 30 per cent loss and deliveries were 18 months behind programme. The new management team had two months to decide whether to accept the option or pull out. After that the MOD would go to competitive tender.

The decision was a fundamental one for Royal Ordnance. To pull out of the contract would mean in effect surrendering the rifle business to competitors, but if the contract was accepted it was clear that radical changes would be required to cut costs and reverse the losses. The management team chose to stay in the market and fight. The events that followed, which are described in this paper, illustrate the step function in change that successful companies are having to make to stay ahead of the competition.
The Challenge and Potential of Metal Matrix Composites
Authors: Ball M J
Published: February 2007

Metal matrix composites offer considerable potential for significant weight savings in aerospace structures. This paper reviews the types of metal matrix composite, particularly with respect to properties and potential applications.
Split Torque Helicopter Transmissions with Widely Separated Engines
Authors: White G
Published: February 2007

A three-stage helicopter transmission of split torque type is shown to offer advances in a configuration that allows the engine axes to be widely separated and parallel.

Three variants of the configuration are examined; one design with separated drive paths and four final-drive pinions is discussed in detail. This design offers 26 per cent less weight and 9 per cent lower losses than current production transmissions.

Comparison is made with epicyclic type transmissions of similar rating that have been developed in the past decade.
Slip Line Field Analysis of a Simple Plane Strain Closed-Die Forging
Authors: Srinivas M V , Alva P , Biswas S K
Published: February 2007

A slip line field is proposed for symmetrical single-cavity closed-die forging by rough dies. A compatible velocity field is shown to exist. Experiments were conducted using lead workpiece and rough dies. Experimentally observed flow and load were used to validate the proposed slip line field. The slip line field was used to simulate the process in the computer with the objective of studying the influence of flash geometry on cavity filling.
Discharge Coefficients for Miniature Fuel Injectors
Authors: Fox T A , Stark J
Published: February 2007

This technical note presents experimentally determined discharge coefficients for miniature, sharp-edged, short-tube orifice injectors operating under quasi-steady conditions in the pre and post-hydraulic flip stages.
The Role of Prototypes in Managing Product Innovation Risks
Authors: Bergwerk W
Published: February 2007

Current views on innovation management regard the prototype as just another stage in the engineering department's development work. It is more realistic, however, to view the prototype stage as a means by which all departments of a company can manage the risks associated with a new product. People judge risk in a very personal manner and different views can easily give rise to tensions which impede progress. The paper proposes methods for achieving concerted action by allowing for various risk perception problems. Particular attention is given to departments not directly responsible for the prototype to ensure that they too contribute constructively to the corporate risk assessment. An open and consistent approach to risk taking is particularly important in large companies if the spirit of innovation is not to succumb to the unavoidable bureaucracy of formal procedures.
An Approach to the Low-Cost Computer Aided Manufacture of Components Embodying Free-Form Surfaces
Authors: Gao X , Harrison D K , Davies B J
Published: February 2007

The numerical control (NC) machining of free-form surfaces is usually accomplished utilizing minicomputer or mainframe computer aided design and manufacturing (C ADC AM) systems. The resulting NC data are suitable for either three-axis or five-axis machining dependent upon machine tool type/capability and CAM package complexity. However, the cost of such packages and systems precludes the use of these in smaller companies with an occasional requirement for components embodying free-form surfaces. The increasing availability of powerful yet reasonably priced personal computers (PC) coupled with improving software provides such companies with a far cheaper alternative approach. However, a common feature of PC-based CADCAM systems is that they are limited to 2 1/2-axis machining for all but special applications such as three-axis canted Z-plane milling of four-axis wire electro discharge machining (EDM).

This paper presents a method for manufacturing true three-dimensional free-form surfaces using PC-based 2 1/2-axis CADCAM systems. All the main functions performed on mainframe systems can be performed on personal computers, such as toolpath generation for free-form surfaces, cusp height determination and change in shape and volume which may be used for the compensation of shrinkage or to suit market requirements. This is significant for manufacturers who make use of moulds, such as are found in the plastic processing industries.

The manufacture of a blown plastic bottle mould is presented as a typical example.

The inclusion into the PC environment of features to be found in mainframe systems is also discussed, such as machining the surface patch by patch in any direction or machining a number of patches at one time, shape and volume change in any direction, cusp height determination, etc.
Helicopter Transmissions—design for Safety and Reliability
Authors: Astridge D G
Published: February 2007

Recent improvements in design and component technologies are reviewed against a background of accident data analysis, resulting in grounds for confidence in higher safety levels in future rotorcraft transmission designs. Recommendations are made concerning the realization of significant safety and reliability benefits afforded by effective health and usage monitoring systems.

The results of this study are applicable to all new aerospace gearbox applications including helicopters, tilt-rotor aircraft, advanced propeller engines and accessory drive systems.
Experimental Evaluation of ‘Shape from Shading’ for Engineering Component Profile Measurement
Authors: Al-Kindi G A H , Baul R M , Gill K F
Published: February 2007

This paper examines the application of the ‘shape from shading technique’ for three-dimensional surface geometry measurements and object inspection. The results for diffuse, specular and combined models are presented for a range of components exhibiting flat to highly curved surfaces. A more representative relationship between surface radiance and image intensity has been developed which, when incorporated in the models, is shown to change the accuracy of profile measurement.
Force Analysis of Robot Manipulators
Authors: Megahed S M
Published: February 2007

The design of a robot manipulator to perform a certain task needs the knowledge of the forces and moments exerted on its joints due to static and dynamic loads. This paper presents a mathematical algorithm for computing the joint forces and moments of the robot arm using the Newton-Euler formulation due to a specified load at its end effector. The computation complexity of an n joint robot arm of a general structure is optimized to need 107n multiplications, 113n additions and 81n equations. A computer program has been developed to perform these computations. Two examples are presented to show the computation procedure: a simple arm of two links and the J PL robot arm of six links. This study is very important for the choice of robot dimensions, the material and shapes of links, and the actuators of joints. It provides the predesign stage of robot manipulators.
The Excitation and Consequences of Acoustic Resonances in Enclosed Fluid Flow Around Solid Bodies
Authors: Parker R , Stoneman S A T
Published: February 2007

A survey is made of enclosed flow systems in which acoustic and/or mechanical oscillations can be excited by vortex shedding from bodies immersed in the flow which becomes ‘locked’ to an acoustic resonance.
Transient Performance Testing of a Parabolic Trough Concentrating Solar-Energy Collector
Authors: Prapas D E , Norton B , Probert S D
Published: February 2007

Based on the response function, a method has been developed which enables a solar-energy collector's performance to be characterized even under intermittently sunny conditions. The accuracy of this transient-testing method, as well as the equipment required for its effective application, are described. The performance of a low-concentration-ratio tracking parabolic-trough solar-energy collector exposed to ambient environmental conditions has been deduced. Initially, a commercially manufactured collector was tested over a period of one month. A second series of measurements was carried out after improvements had been made to the collector. The effect of the variation of the ratio of the diffuse to the total insolation on the performance of the collector has been determined.
A Comparison of Ratings for Plastic Gears
Authors: Walton D , Shi Y W
Published: February 2007

The failure mechanisms of plastic gears are examined and methods for calculating tooth bending and surface contact stresses for non-metallic gears are reviewed. The applications and limitations of the Lewis equation and Hertzian contact theory are considered and comparisons made between steel and plastic conditions, gear standards and various commercial rating practices for plastic gears. Special emphasis is laid on the British Standard BS 6168: 1987, the Polypenco rating method and ESDU 68001 for the design of non-metallic gears. A comparison is made between gears of different materials and material combinations, and for gears running under dry and oil-lubricated conditions. The effects of gear speed on ratings are briefly examined. As a result some shortcomings in the various rating methods are mentioned.
Analysis of Displacements and Stresses in Oil Storage Tanks Caused by Differential Settlement
Authors: Kamyab H , Palmer S C
Published: February 2007

Differential vertical settlement around the circumference of the foundations of large open-topped oil storage tanks can produce deformation of the tank including radial deflection of the tank shell. Excessive radial deflections may result in jamming of the floating roof.

The results of an analysis by Malik et al. (1), based on the assumption that the behaviour of the shell is inextensional, are outlined.

Two further analyses of the tank shell and the primary wind girder are presented. Both of these are simple, but use less restrictive assumptions than in reference (1). In the first analysis the shell is considered to act as a membrane. The second analysis makes use of a simplified version of the modified Donnell equation. The results of these analyses are compared with those of the analysis based on the inextensional behaviour of the shell. The limits of validity of the three different analyses are identified.

It is proposed that the membrane solution is valid for all practical applications, and the results are presented in non-dimensional form in Fig. 6.
Analysis of Compressed Air Flow Through a Spool Valve
Authors: Mo J P T
Published: February 2007

A pneumatic servo-mechanism with a sophisticated control algorithm based on variable closed-loop gains has been developed recently on specially designed pneumatic drives. Unfortunately, due to the compressibility of air, models derived using traditional linearization methods could not describe the behaviour of the system over its full stroke and hence prevented the generalization of the control algorithm on a commercial platform. The problem is tackled by the component-oriented approach which segregates the pneumatic servo-mechanism into individual components for more precise analysis. This paper describes the analysis of one of the components—a five-port spool valve from the concept of a flow node in the valve land. The new valve model, which incorporates an extension to include an upstream flow head in the one-dimensional adiabatic flow equation, can predict the mass flowrates at all spool displacements satisfactorily. The flow node model can also be used to derive the theoretical pressure variations due to leakage which cannot be deduced in the conventional approach.
Advances in Hydrostatic and Hybrid Bearing Technology
Authors: Rowe W B
Published: February 2007

This review outlines the highpoints in the development of hydrostatic and hybrid bearing technology from early plane and cylindrical designs to the wide range of configurations now utilized. The last 20 years have seen increasing sophistication of software for bearing analysis accompanied by application of hybrid bearings to more demanding situations, involving high loads, high speeds and high accuracy. The emphasis in this review is on advances in the realization of the distinctive characteristics of this important group of bearings and on the selection of the design approach for different situations. Applications discussed range from measuring and machine tools to aerospace and heavy power generation equipment. Aspects covered include load coefficients, film stiffness, flow control, hydro-dynamic effects and dynamic behaviour.
Theoretical and Experimental Study of the Effect of Varying Load on the Dynamics of a P, MRC or P + PID/x Controlled Electrohydraulic Position Servo System
Authors: Pietola M T , Vilenius M J
Published: February 2007

The effect of varying load conditions on dynamic and static properties of a flexible electrohydraulic position control servo system is investigated theoretically and experimentally in this paper. Three different control methods were used. P control was taken into the research as a reference. P + PID/x; was used because it is a good method of damping the oscillations of flexible servos. Model reference control (MRC) was included as a new possible method of getting good dynamic results. In the mathematic analysis the aim was to develop system models that are not too complicated but still describe well this kind of heavily loaded flexible servo system. The non-linearities included were the dead band and saturation of the valve and the non-linearity of the load flow.
The Stirling Cycle as a Linear Wave Phenomenon
Authors: Organ A J , Jung P S
Published: February 2007

The exchanger system of the Stirling cycle machine is modelled as some hundreds of wave-reflection sites representing the flow area discontinuities of individual tube transitions and regenerator gauzes. The methods of linear, inviscid, one-dimensional wave theory permit pressure and velocity to be predicted over a complete cycle in function of time and location in a single computational sweep of the flow passage system. Results computed for a specific Stirling machine are compared with the experimental counterpart. The comparison provides a tentative explanation for the frequently reported discrepancy between pressure characteristics measured experimentally and those derived from computer simulations based on steady-flow correlations between Cf and NRe.
Probability of Scuffing in Lubricated Contacts
Authors: Stolarski T A
Published: February 2007

An analytical determination of the probability of scuffing is presented and used to modify and extend a computer program that was the subject of earlier work. The program identifies conditions that produce boundary or mixed lubrication with asperity overlaps for which the plasticity index is greater than 0.6. It then imposes, as a necessary prerequisite for scuffing, the condition that the surface bulk plus flash temperature is high enough to cause significant desorption of adsorbed lubricant film. For such conditions determination of the probabilities of asperity contact and of plastic asperity contact provide upper and lower bounds respectively to the probability of scuffing. It is shown that in this way critical ranges of conditions can be clearly distinguished from ranges for which scuffing is unlikely.
Estimation of Minimum Thickness for Line Contacts in the Transition Region between the Isoviscous—Elastic and the Piezoviscous-Elastic Lubrication Regimes
Authors: Jaffar M J
Published: February 2007

This paper represents a solution for lubricated cylinders in line contact operating in the transition region between isoviscous-elastic and piezoviscous-elastic conditions. The computer solutions are used to generate a formula for the minimum film thickness. The approximate formula is compared with the existing formulae at the boundaries of the lubrication regimes where good agreement is obtained. Also, the influence of the starvation on pressure and film thickness is investigated.
Central Film Thicknesses in Elliptical Contacts
Authors: Sutcliffe M P F
Published: February 2007

Published theoretical calculations for central film thicknesses in circular and elliptical contacts are compared in order to identify the physical processes determining film thicknesses in the piezoviscous regime as conditions change from elastic to rigid. It is suggested that the reduction in film thickness below an asymptotic calculation found by Hooke (1) for conditions well into the elastic piezoviscous regime can be accounted for by side leakage of oil in the inlet.
On the Deployment of Automotive Engineers
Authors: Bertodo R G
Published: February 2007

British automotive design philosophies, engineering traditions, organizational structures and managerial practices have been geared to the generally recognizable European product concept. This distinctiveness has been eroding due to the convergence of Japanese and North American trends towards European values. Regaining the competitive edge has become the challenge facing the industry. The present paper describes a determined attempt to do so.

Earlier investigations had shown that, in automotive engineering, the attainment of customer-perceived superb ‘quality’ was the only assurance of market acceptability and competitiveness. Traditional design methodologies were demonstrated as inadequate and incapable of ensuring the attainment of product attributes in line with end-user needs and expectations. The subsequent evaluation of an alternative design logic indicated the need for a reappraisal of the engineering culture.

The organizational, managerial and operational changes necessary to implement this new philosophy are described in detail. A preliminary quantification of the benefits reaped are presented. Scope for further improvement is shown to exist. Although the transition was broadly successful, different areas showed different rates of progress. This highlighted the need for a commonality of ethos, objectives, goals and understanding by all. Apprehension and discomfort was encountered at all levels, but was particularly evident among middle management. This underlined the importance of mutual trust, good communications and appropriate training.

The continuing evolution of the automotive industry and the pressing challenge of competition will force ongoing changes in engineering organizations to meet new market needs. The likely directions of such changes in the management of automotive engineering work are outlined.
Design for Assembly—A Key Element within Design for Manufacture
Authors: Miles B L
Published: February 2007

This paper will consider design for assembly (DFA) and its role within a design for manufacture (DFM) programme, placing particular emphasis on those elements with which it has strong synergy, namely simultaneous engineering, product teams and other DFM techniques.
The Effect of Vaneless Diffuser Geometry on the Surge Margin of Turbocharger Compressors
Authors: Whitfield A , Sutton A J
Published: February 2007

A study into the effect of two methods of changing the geometry of a vaneless diffuser on the performance of the compressor of a road haulage diesel engine turbocharger is described.

The development of compressor variable geometry will enable the full potential of variable geometry turbines to be realized. This will give a more flexible power unit which will provide, for example, better low-speed torque and hence a smaller gearbox, and shorter journey times or larger payloads than are currently the practice. The disadvantages are added complexity and cost in the relatively simple turbocharger, and the need for an engine management system. The latter is currently being implemented on many vehicles to meet tight emissions regulations in Europe and elsewhere, and is thus not a drawback limited to variable geometry turbocharging.

A compressor test facility, including appropriate instrumentation and a computer-based data-acquisition system, was constructed with the specific aim of investigating the unstable flow regime prior to and including surge. Alternative fixed vaneless diffuser geometries were designed to simulate a variable geometry diffuser which could be achieved through a flexing diffuser wall and a sliding throttle ring.

Both the converging wall and throttle ring arrangement moved the peak pressure ratio to lower flowrates, and at the near surge flowrates (where the device would be introduced, when operating in a variable geometry mode) improvements in both pressure ratio and efficiency are shown. While the converging wall concept exhibited slightly better aerodynamic performance than the throttle ring, it has implementation difficulties with respect to material integrity under continuous flexing when developed to a fully variable geometry device. The simplicity of the sliding throttle ring makes it a more viable proposition. Prototype variable geometry (VG) devices have been constructed with a view to further rig and engine testing.
Theoretical and Experimental Investigation of a Pressure-Relief Valve for Variable Compression Ratio Pistons
Authors: Ladommatos N , Barber J R , Brown I A C
Published: February 2007

This paper reports the development of a digital computer simulation model for a pressure-relief valve of the differential-angle type which is suitable for use in variable compression ratio pistons. The model was validated using experimental results and is intended as an aid to design. It can predict under unsteady flow the pressure distribution through the valve, the opening and closing pressures, volume flowrate, plunger velocity, and opening period. Predicted and experimental results are presented which show the effect of the valve geometry on its performance. The theoretical approach is also applicable to diesel engine fuel injectors of the differential-angle type.
Theoretical Analysis of Active Suspension Performance Using a Four-Wheel Vehicle Model
Authors: Hady M B A Abdel , Crolla D A
Published: February 2007

Techniques for obtaining control laws for an active suspension implemented at all four wheel stations of a vehicle are outlined. It is shown that the classical optimal control law based on full state feedback can be replaced by one that involves limited state feedback—omitting, in particular, the ground input information—and that may involve measurement errors. Performance of this system is almost as good as that of the full state feedback system and is much more attractive in terms of its practical implementation.

Previous work, much of which has been based on the quarter car model, is extended so that the performance indices may include body roll, body pitch, seat lateral acceleration and lateral and fore/aft dynamic load transfer.
Corrugation of Unmetalled Roads Part 2: Wheel-Soil Interaction
Authors: Misoi G K , Gichaga F J , Carson R M
Published: February 2007

The paper relates the dynamics study of Part 1 to the creation of corrugations. Experiments on soil movement using photography and tracer particles are reported. The local variation of soil strength and particle size within the corrugation profile have also been measured, and the liability of different road materials to corrugation has been related to the bulk properties of the soil. The effect of rainfall is discussed. Finally, the implications for practical methods of preventing corrugation are suggested.
A Practical Control Concept for Passenger Car Active Suspensions with Preview
Authors: Foag W
Published: February 2007

The message of this simulation and optimization-based design study is threefold: first, short-distance (below 2 m) road profile preview substantially improves all relevant performance criteria of an active suspension; second, controller design for such a preview suspension can be done in a pragmatic, yet systematic way; and third, the preview (feedforward) part of the control law can co-operate harmonically with the controller of an already conceived or existing feedback-only active suspension.
Design and Testing of a Servo Controller for Pneumatic Cylinders
Authors: Marchant J A , Street M J , Gurney P , Benson J A
Published: February 2007

A closed-loop method of controlling a pneumatic cylinder is proposed where the cylinder can respond to varying position demands from an external source.

The method uses a state space design technique involving the experimental identification of a dynamic model for the cylinder and valve combination. Data for the identification are obtained from an initial phase in which the valve and cylinder are excited by an operator. The controller constants are then derived using a pole placement design technique. The model and control constants are derived within the controller, resulting in automatic tuning.

Experimental data are presented in response to step and ramp inputs. With moderate closed-loop bandwidths the response is well damped but as the designed bandwidth increases, lightly damped oscillations occur in the response, probably caused by differences between the responses of the experimental system and its model. If greater closed-loop bandwidths are required further work needs to be done on the form and order of the model.
A Survey and Analysis of Process Plant Maintainability Problems
Authors: McKinney M , Thompson G
Published: February 2007

The objective of this paper is to determine whether or not maintainability problems exist which are common to different plants within the process industries. An extensive literature survey has been carried out encompassing academic and professional publications. This research has been supported by visits to fourteen production sites. It has been possible to identify items of equipment which commonly are seen to be maintainability problems. The reasons for poor maintainability are analysed with respect to the basic design of equipment and directions for further research are identified.
An Experimental Study of a Plasto-Hydrodynamic Strip Drawing Process
Authors: Memon A H , Symmons G R , Crampton R , Hashmi M S J
Published: February 2007

Experimental results are presented for a new dieless strip drawing process in which conventional wedge-shaped dies have been replaced by a reduction unit having a stepped rectangular cavity. The smallest cavity dimensions are larger than those of the incoming strip, thus eliminating the problem of die friction and consequential tool wear.

In this novel process, the strip is passed through a chamber filled with polymer melt and then pulled through the reduction unit. The strip material is deformed due to the combined effects of shear drag and the hydrodynamic pressure generated by the converging flow of the polymer melt.

Experiments were carried out in which the process parameters such as the unit geometry, speed and polymer melt temperature and hence viscosity were varied and the hydrodynamic pressure, reduction in strip size and drawing load were measured. Initial experiments were carried out by using copper strip and low-density polyethylene at two different melt temperatures. Results from experiments showed that a reduction in area of strip of more than 10 per cent could be achieved in a single pass.

The Newtonian analysis presented by the authors in reference (9) is modified to incorporate the critical shear stress limit of the polymer melt and the non-linear strain-hardening property of the strip material.
A Study of the Parametric Effects on Magnetic Coal Ceaning
Authors: Lua A C , Boucher R F
Published: February 2007

A coal-cleaning technique was evaluated to determine its effectiveness to remove sulphur and ash contents of dry pulverized coals before combustion in power stations. Dry high-gradient magnetic separation (HGMS) experiments were conducted on a British coal from Coalfield Farm North using ferromagnetic stainless steel wire meshes as the separator matrix which was located in the bore of a superconducting solenoid magnet. The parametric effects of magnetic field, air velocity and separator length on the process were investigated. Increasing magnetic fields and separator lengths and decreasing air velocities each individually increases the percentage reductions of pyritic sulphur, total sulphur and ash. Reduction efficiencies up to 91, 65 and 61 per cent for pyritic sulphur, total sulphur and ash respectively were obtained. These results have at least shown that dry HGMS could possibly provide a simple and economic alternative to flue gas desulphurization to reduce sulphur dioxide emissions to the atmosphere from coal-fired power stations, with the additional benefit of an ash removal capability.
An Alternative Bolted Joint for Pipework
Authors: Webjörn J
Published: February 2007

Use of the conventional gasketed pipe joint with raised-face flanges is questioned. In this note the author demonstrates the interaction of forces and displacements within the structure, explains why gaskets leak, points out the weaknesses of the bolting and also some inconsistencies in codes and standards. An alternative compact flange design is presented based on modern principles of bolted joint engineering.
The Railway Family
Authors: Lyall A M
Published: February 2007

The Railway Division Chairman reviews his career in Metropolitan Vickers, later GEC, in relation to the worldwide fraternity of railway engineers. He outlines his involvement with the ‘Blue Trains’ and the development of semiconductors and explains how particular problems have been overcome. He discusses the marketing of overseas contracts and describes some of the more recent locomotives that have been successful both in the United Kingdom and overseas. He concludes by mentioning the railway enthusiasts and their contribution to the ‘railway family’.
Behaviour in Track of Concrete Sleepers with Resilient Railpads
Authors: Grassie S L
Published: February 2007

Loading under traffic of concrete sleepers with a variety of resilient railpads is examined using data from several field experiments. In all cases dynamic loads on sleepers were significantly reduced using the pads. Quasi-static load reduces the ability of railpads to attenuate dynamic loads by a small but consistent amount. Dynamic loads are appreciably greater with poorly packed ballast. Short wavelength irregularities which most significantly affect dynamic loading of track are not detected by conventional track geometry cars.
From Vertical to Horizontal Diesel Engines For Railcars—A Development Story
Authors: Miles R A
Published: February 2007

British Rail's Class 15X series of diesel railcars weigh much the same as modern heavy goods vehicles and require a similar power-weight ratio. Therefore it is natural that horizontal railcar engines should derive from the highly developed truck power units. This paper describes the special features necessary to make the transition from the vertical to the horizontal engine in a form suitable for the British Rail railcars. As now developed, the engine has been installed in the prototype Class 154, and provides power suitable for a number of railcar specifications requiring 224–261 kW (300–350 hp).
Diagnostic Systems
Authors: Waterman A W
Published: February 2007

A seminar on ‘Diagnostic Systems’ was organized by the Railway Division of the Institution of Mechanical Engineers and jointly sponsored by the Institution of Electrical Engineers: it was held in London on 27 October 1988.
A Study on the Thermal and Residual Stress by Welding and Laser Surface Hardening Using a new Two-Dimensional Finite Element Model
Authors: Yang Y S , Na S J
Published: February 2007

The transient thermal stress and residual stress in bead-on-plate welding and laser surface hardening was analysed by employing a new two-dimensional finite element model. In the formulation, the sliced solution domain possessing one element in the welding or hardening direction was introduced to allow the change of longitudinal total strain along the width and depth of the specimen. The longitudinal total strain, which makes the resultant force in the longitudinal direction zero, was used as the boundary condition. To determine the longitudinal total strain, the equations of the compatibility, force equilibrium and moment equilibrium were considered. Calculation of the transient temperature distribution was based on the two-dimensional finite element model of the quasi-stationary condition.

By using the proposed model the thermal and residual stresses of the bead-on-plate welding and laser surface heat treatment were successively calculated. Especially in laser surface hardening, the thermal stress was induced mainly from the temperature gradient and martensitic phase transformation, which was found to have a greater influence on the residual stress than the former. The computed results were compared with those obtained by the conventional two-dimensional model of the plane strain condition. The simulation results revealed that the present model could more reasonably describe the thermal and residual stresses than the plane strain model.
Effect of Casing Treatment on Aerodynamic Performance of a Contrarotating Axial Compressor Stage
Authors: Pundhir D S , Sharma P B , Chaudhary K K
Published: February 2007

The paper reports the results of an experimental investigation on the effect of casing treatment on aerodynamic performance of a low-speed contrarotating axial compressor stage having a hub-tip ratio of 0.667. Three types of casing treatments, namely axial slots, axial skewed slots and circumferential grooves, have been examined. Flow structure downstream of the rotors is examined for treated casing and compared with solid casing. The results show a significant improvement in stall margin and efficiency during off-design operation of a contra stage.