bluuebunny/crossref_metadata_2025 huggingface dataset:
A Simulation of Reinforcement Deformation during the Production of Preforms for Liquid Moulding Processes
Authors: Long A C , Rudd C D
Published: February 2007

Composite materials offer an attractive alternative to metals in the automotive and aerospace industries. Of the many possible production methods, liquid moulding processes such as resin transfer moulding (RTM) and structural reaction injection moulding (SRIM) demonstrate potential for high-volume manufacture. It is common to use preformed reinforcements, although this can cause certain problems. Fibre movement during forming can cause adverse effects such as wrinkling and thinning. The high levels of waste generated by subsequent trimming operations are proving unacceptable for medium to high volumes. An accurate modelling capability would allow defects to be predicted at the design stage, and would also allow prediction of the net-shape reinforcement required to form the component with no waste. This paper presents models for both random and directional reinforcement deformation. Random reinforcements are simulated using a modified plasticity theory, while directional reinforcements are modelled using the pin-jointed deformation model.
Computer Aided Design of Feeders for Castings
Authors: Zhang H G , Webster P D , Dean T A
Published: February 2007

This paper describes a software module, contained within a design-for-casting package, which aids the user in designing efficient feeding systems for castings. The user can choose a shape suitable for a particular casting condition from a file containing a variety of feeder head types. The feeder heads are placed relative to the casting in positions appropriate to hot spots identified by a ‘heat centre’ module within the package. The number and size of heads are chosen with the aid of built-in rules that aid the user. The module provides a rationale for people, both skilled and unskilled, who have to design for casting. The validity of the design rules and guidelines within the module is demonstrated by casting three widely different shapes with and without feeders.
Functional Interaction Management: A Requirement for Software Interoperability
Authors: Singh V , Welz F , Weston R H
Published: February 2007

There is a much increased demand for a degree of interworking between software packages as it is no longer reasonable to expect a single application to be able to do its job without support or reference to data and events that are handled by other closely related application systems. In practice, it is essential to help ensure and maintain discipline and harmony to enable graceful co-operation among interoperating software components. Functional interaction management is identified as a vital service requirement necessary to help address this issue of software interoperability. Current manufacturing control systems (MCS) exhibit deficiencies and constraints that inhibit or complicate their interaction. This paper reports on ongoing research work where the main thrust is to derive a new generation of reconfigurable and modular forms of MCS, the components of which can ‘functionally interact’ and share common information through accessing distributed data repositories in an efficient, changeable and standardized manner. The emphasis is on:

(a) development of an effective framework to manage functional interaction between MCS components, which typically may comprise software packages that facilitate production planning, product design, finite capacity scheduling and cell control; (b) ‘soft’ integration of these MCS components over the CIM-BIOSYS integrating infrastructure.
Elastic Damage Analysis of Interlaminar Stress Distributions in Symmetrical Composite Laminates with Edge Delamination Cracks
Authors: Chow C L , Yang F
Published: February 2007

This paper is intended to present a study of elastic-damaged behaviour of symmetrical composite laminates with edge delamination cracks subjected to uniformly applied uniaxial tensile load. The response of composite laminates is investigated by a quasi-three-dimensional finite element analysis including the damage characterization of constituent plies. Of principal concern are the effects of edge delamination cracks as well as the influence of damage on stress distributions in graphite/epoxy [0/90°]s, [90/0°]s and [±45°], laminates. The computed results between the behaviours of laminates with stiffness damage consideration and those of geometrically similar laminates without stiffness damage are compared and the significance of damage in stress analysis of fibre-reinforced composite materials is elucidated.
Modelling of the Steel Pushing V-Belt Continuously Variable Transmission
Authors: Micklem J D , Longmore D K , Burrows C R
Published: February 2007

The steel pushing V-belt continuously variable transmission (CVT) is now commercially available in the automobiles of a number of manufacturers but to date it has not led to a significant reduction in fuel consumption. To develop its full potential it is necessary to have a good mathematical model of the system. A number of models have been described in recent years but all make use of a Coulomb friction model for the shear connection between the belt and the pulleys. This paper proposes a friction model based on elastohydrodynamic theory. It is shown that there is good agreement between measured and calculated slip values for the transmission which justifies use of the model.
End-Stage Boundary Layer Transition Models for Engineering Calculations
Authors: Fraser C J , Higazy M G , Milne J S
Published: February 2007

The paper presents some recent new data on the combined effects of pressure gradient and freestream turbulence level on the onset and length of the latter stages of the boundary layer transition process. Generalized correlations for the transition length Reynolds number are developed from considerations of the non-dimensional turbulent spot formation rate. The optimized correlation is built into a popular linear combination integral computer code to predict the growth of the transitional boundary layer in a number of practical engineering flows.
A Study on Determining Loops of Planar Kinematic Chains
Authors: Li W , Wang Z , Li H
Published: February 2007

This paper presents for the first time a method for the automatic generation of independent and peripheral loops of planar kinematic chains. In order to implement this method, three laws are considered and some new concepts, for instance same-position link, similar loop, loop-link vector and loop-joint vector, are defined. By using structural matrices of planar kinematic chains, independent loops are generated in the order from those with small length to those with large length. Next, one peripheral loop with the maximum length is generated. Finally a loop-link matrix and a loop-joint matrix are obtained to express all independent loops and the peripheral loop in a planar kinematic chain.
Load Sharing in Metallic and Non-Metallic Gears
Authors: Walton D , Tessema A A , Hooke C J , Shippen J M
Published: February 2007

A review of work on tooth deformation and load sharing in non-metallic gears is presented. A finite element analysis employing the flexibility method for contacting bodies is used to model tooth deflections and contact patterns between meshing gears For metallic gears the change in contact ratio between the theoretical and running values is shown to be small. However, for low modulus, non-metallic gears the change in contact ratio is large and can give cause for concern. The benefits and disadvantages of this increase in operating contact ratio is stated. Finally, the possibility of characterizing the change in operating contact ratio in a non-dimensional form is discussed.
On the Turbulent Flow Downstream of a Partly Opened Throttle Valve
Authors: Hu T-F , Hsu Y-Y
Published: February 2007

Experimental measurements were performed in a model inlet pipe on the turbulent flow downstream of the throttle valve of a commercial motorcycle carburettor. The inlet pipe was made of a section of straight plexiglass tube to facilitate the access of hot-wire and pressure probes. Continuous dry air was drawn into the model to establish the flow. The flow downstream of the partly opened throttle valve is found composed of a recirculation region, a three-dimensional jet stream and a wall boundary layer. Complex turbulent flow interactions among the recirculation region, the jet stream and the boundary layer are observed. This study clearly demonstrates that the jet stream, which includes a major portion of the flow going downstream, shows similarity of axial velocity profiles on planes normal to the angular direction.
Numerical Simulation and Experimental Investigation of Compression Processes of Two-Stage, very High Pressure Reciprocating Gas Compressors
Authors: Hsieh W H , Wu T T
Published: February 2007

To help the design of more reliable and efficient two-stage, very high pressure reciprocating gas compressors, a theoretical model and a numerical code for simulating compression processes in the compressors were developed and validated. The theoretical model considers time-dependent conservation equations of species, mass and energy, the equation of state, kinematic relationships and various convective heat-transfer correlations The theoretical model was solved numerically. Experimentally, a 207 MPa (30 000 lb/in2) very high pressure gas compressor was instrumented for measurements of various transient flow properties. The experimental data were analysed to achieve a better understanding of the compression processes of the compressor as well as for model validation. A parametric study was conducted with the theoretical model and numerical code to investigate the effect of various compressor parameters on the compressor performance. Among the parameters studied, it was found that the dead-end volume had the strongest effect on the performance of the compressor. A reduced dead-end volume would increase the volumetric efficiency and the maximum gas-phase temperature and pressure in the first-stage cylinder.
Experimental Approach to Electrostatic Liquid Filtration Using a Single Fibre Model: Part 2: Effects of Mechanical Factors
Authors: Yanada H , Takikawa Y
Published: February 2007

This paper is concerned with an experimental investigation of an electrostatic liquid filter in which a collector is modelled as a single fibre. The effects of mechanical factors such as flow velocity, electric field strength, relative arrangement of collector fibre to flow, etc., on the deposition quantity of particles are studied. The study has shown that a flow velocity exists which produces a maximum deposition quantity and the value of the velocity varies from one test oil to another. It has been found that the deposition quantity is strongly affected by the relative arrangement of the collector fibre to flow. The study has also shown that the deposition quantity differs considerably according to the relative direction of flow and electric field, especially when particles in the oil are distinctively charged positively or negatively.
A Systems Approach to the Torsional Vibration of Multi-Cylinder Reciprocating Engines and Pumps
Authors: Hesterman D C , Stone B J
Published: February 2007

The systems approach for the vibration analysis of complex systems requires that the receptances of the sub-systems are available. For the torsional vibration of rotating systems including reciprocating engines and/or pumps it has been the practice to represent the reciprocating mechanism by a constant rotary inertia. This paper describes the derivation of the receptance for such reciprocating mechanisms, which includes the effects of non-constant rotary inertia. It is then shown how the natural frequencies for torsional vibration vary with angular position and how this in turn affects the vibration in the time domain. The significance of the effects indicated by these simulation techniques is then demonstrated by comparing with results obtained from an experimental investigation.
Throttleless Premixed-Charge Engines: Concept and Experiment
Authors: Ronney P D , Shoda M , Waida S T , Durbin E J
Published: February 2007

A method of controlling the brake mean effective pressure (b.m.e.p.) of a premixed-charge engine is proposed which does not require the use of a throttle and does not exhibit significant throttling losses. In this method, a combination of adjustment of the mixture equivalence ratio and preheating of the mixture is used to control the b.m.e.p. The preheating serves two purposes: it reduces the density of the mixture and it broadens the lean misfire limit. Experiments on the performance of engines controlled with this strategy are compared with conventional throttled engines. As much as 16 per cent improvement in thermal efficiency was observed at the same b.m.e.p. The untreated NOx emissions are found to be much lower in the throttleless engine at the same b.m.e.p. while carbon monoxide (CO) and unburned hydrocarbon (UHC) emissions are comparable to but somewhat higher than throttled engines. Practical implementation of the concept is discussed.
Finite Element Modal Analysis of the Engine Front End Accessory Drive Systems
Authors: Zhu H
Published: February 2007

The objectives of the study were to create finite element (FE) models for the engine front end accessory drive (FEAD) systems, to carry out normal mode analyses on the systems and to make a comparison of the predicted frequencies with those of measurement.

The analytical results of three FEAD systems showed that more accurate frequencies were calculated using the complete accessory model than the concentrated mass model. Therefore the complete accessory model should be created for structural analysis of the FEAD systems. It was also pointed out that great care should be taken in the creation of FE models.
Automotive Materials Recycling for the Future
Authors: Shergold M
Published: February 2007

Environmental issues are occupying an increasingly high profile in all our lives. For many years, the motor industry has been conscious of the need to reduce the impact of our products on the environment, particularly in terms of tailpipe emissions. In recent years, the disposal of end-of-life vehicles has also gained a measure of public visibility.

This paper examines the current disposal situation for end-of-life vehicles and considers the impact of developments in vehicle design on the existing infrastructure from both a technical and a commercial perspective. An industry-proposed improvement strategy is briefly described and the technical and infrastructural issues arising are considered.
Neural Classifiers for Automated Visual Inspection
Authors: Pham D T , Bayro-Corrochano E J
Published: February 2007

This paper discusses the application of a back-propagation multi-layer perceptron and a learning vector quantization network to the classification of defects in valve stem seals for car engines.

Both networks were trained with vectors containing descriptive attributes of known flaws. These attribute vectors (‘signatures’) were extracted from images of the seals captured by an industrial vision system. The paper describes the hardware and techniques used and the results obtained.
Belt Torque Loss in a Steel V-Belt Continuously Variable Transmission
Authors: Micklem J D , Longmore D K , Burrows C R
Published: February 2007

To achieve the potential advantages to be gained by the use of a high ratio range, continuously variable transmission (CVT) in an automobile it is important that the system has a high efficiency and that any inherent loss mechanisms are fully understood.

This paper investigates the belt-related torque loss in a steel V-belt CVT. Measurements show that the loss is dependent on the secondary pulley clamping force and on the belt configuration and these results are presented in the paper. A semi-empirical model is proposed to explain the loss. The agreement between the measured results and the values calculated from the model is shown to be good.

It is also shown that when the system is in an overdrive ratio and a high efficiency is particularly important the torque loss is large and the efficiency is severely limited, probably to less than 90 per cent.
Effect of Throttle Configuration on Wall Flow Behaviour of Fuel in a Carburetted Induction System
Authors: Abbass H A , Raman N , Narasimhan M V
Published: February 2007

The wall mass flow of fuel in the manifold of a carburetted induction system, known to have a significant effect on fuel maldistribution and air-fuel ratio excursion, is studied experimentally with a conventional and variable-area convergent/divergent throttling device. The thickness and velocity of the wall film is calculated using the measured wall mass flow. The effect of the stream velocity, throttle position and air—fuel ratio on wall mass flow and on the thickness and velocity of the film is reported. The wall mass flow decreases as the stream velocity increases and shows a tendency to stabilize at a velocity of about 100 m/s. It also decreases with smaller throttle openings and leaner mixtures. However, with the conventional throttle it shows a tendency to increase for throttle openings less than a quarter. The film thickness is found to be in the range of 0.014–0.025 mm. The effect of the experimental parameters on film thickness is similar to that on wall mass flow. The film velocity is in the range of 20–54 mm/s and is influenced by the air—fuel ratio and throttle position. Film velocity increases as the stream velocity increases for a film thickness larger than 0.1 mm. For a film thickness less than 0.1 mm, stream velocity is observed to have no effect on film velocity. The effect of the new throttling device in reducing wall mass flow is very significant in the near closed to part throttle conditions.
Efficiency of the SI Engine Fuelled with Methanol—Gasoline Blends
Authors: Kowalewicz A
Published: February 2007

Investigations of the influence of methanol content in methanol—gasoline blends on engine efficiency have been carried out. It is shown that the higher the methanol content in the blend, the higher the engine efficiency. Among possible reasons for the increased efficiency is that combustion losses are lower for higher methanol content in the blend. Estimation of combustion losses are discussed herein.
Investigation of the Benefits of Controlling the Start of Combustion in a Direct Injection Diesel Engine Using an Optical Sensor
Authors: Ladommatos N , Balian R A , Horrocks R , Cooper L
Published: February 2007

Results are presented which show the effect of controlling the start of combustion on direct injection diesel engine exhaust emissions at various engine operating conditions. The ability of the sensor to detect reliably the start of combustion under various engine conditions is first assessed. The effects on exhaust emissions of controlling the start of combustion is then evaluated using a fuel of reduced ignition quality.
Flow and Combustion in a Transparent 1.9 Litre Direct Injection Diesel Engine
Authors: Arcoumanis C , Whitelaw J H , Hentschel W , Schindler K-P
Published: February 2007

Two identical 1.9 litre direct injection (DI) diesel engines having optical access for application of laser diagnostics were operated at Volkswagen and Imperial College as part of the European programme (IDEA) on diesel engines. A variety of complementary laser-based techniques were used to characterize the flow-generating capacity of the intake system under steady flow conditions, the in-cylinder flow during induction and compression as well as the spray development, auto-ignition and combustion under three typical engine operating conditions. The most important results of this programme are presented and discussed here in view of their implications for improved combustion and reduction of exhaust emissions in small direct injection diesel engines, through better matching of the spray characteristics with the in-cylinder flow as a function of engine speed and load. The results were obtained in sufficient detail to allow validation of the multi-dimensional computer code developed within the IDEA programme.
Tumble and Swirl: Are they a Mixed Blessing?
Authors: Belmont M R , Hacohen J , Carpenter P W
Published: February 2007

The results of a simple simulation model incorporating the cyclic fluctuations in flame velocity resulting from the corresponding variability in turbulence onset and generation imply that at low load conditions such fluctuations can induce changes of the order of many per cent in the indicated mean effective pressure (i.m.e.p.). The methods employed here are relatively unsophisticated; however, the scales of the effects are sufficient to sound at least a cautionary note to the introduction of processes such as tumble collapse into lean burn technologies without taking due notice of the possible disadvantages.
A Novel Active Suspension System for Automotive Application
Authors: Leighton N J , Pullen J
Published: February 2007

This paper describes a novel type of active suspension based on a buckling spring element installed in an actively controlled variable leverage system. The development of the suspension system through stages of computer simulation, implementation and test is outlined, together with the test results. The suspension system does not fall into any of the established categories of active system but may be seen as fitting into a recently identified category of variably leverage systems. The system is shown to be capable of controlling a vehicle body's motion while providing excellent road input isolation and requiring input power levels of below 150 watts per wheel.
Memory-Metal Actuators for Automotive Applications
Authors: Turner J D
Published: February 2007

Shape-memory alloys (SMAs) are a relatively recent addition to the range of materials that can be obtained by the automotive designer. Low-cost SMA springs are now available, which alter in length when their temperature is changed. SMA springs produce a larger force than bimetallic devices, and in addition the full length change occurs quite rapidly, as soon as the threshold temperature is reached, giving a useful ‘bistable’ effect. This technical note describes the application of SMA springs to the design of an actuator, intended for use as a radiator blind forming part of an automotive cooling system. The design process adopted is outlined, together with the subsequent testing of the prototype. It is shown that SMA devices can form the basis of a range of simple, flexible and reliable actuators.
Stresses in Storage Tanks Caused by Differential Settlement
Authors: Palmer S C
Published: February 2007

Differential settlement around the circumference of the foundation below the shell of a vertical cylindrical storage tank is a particularly severe form of settlement, and can cause distortion and stressing of the tank. The resulting deflections and stresses in the shell and primary wind girder of a tank with a floating roof can be analysed, assuming the shell to behave as a membrane. The analysis is reviewed and the results are applied to present a new design chart for predicting the maximum shell membrane stress caused by settlement.

For unanchored tanks, the stiffness of a tank may be such that the shell can ‘bridge’ across localized soft spots in the foundation. A simplified analysis of bridging is presented and a criterion for predicting the onset of bridging is proposed, supported by model test results. Expressions for the associated shell membrane stresses are derived. For unanchored floating-roof tanks, it is concluded that the occurrence of bridging will always limit the maximum shell membrane stress to an acceptable value. However, the bending stresses in the shell-to-base joint of a bridging tank require separate assessment in all cases.

The settlement criteria contained in the current British and American codes of practice for in-service inspection of tanks are reviewed in the light of these findings.
Some Recent Developments in Pressure Vessel Design by Analysis
Authors: Mackenzie D , Boyle J T , Spence J
Published: February 2007

Stress classification is a significant problem in pressure vessel design by analysis, especially if the design is based on solid finite element analysis. Stress categorization may be circumvented if the design is based on elastic-plastic or limit analysis but the degree of difficulty commonly associated with these types of analysis makes this approach unattractive to many designers. In this paper, a brief survey of a number of recent developments in pressure vessel design by analysis is discussed and assessed in light of Code design requirements.
The Twin-Saddle Support of Horizontal Multi-Layered GRP Vessels—Theoretical Analysis, Experimental Work and a Design Approach
Authors: Tooth A S , Banks W M , Seah C P , Tolson B A
Published: February 2007

The maximum stress in a storage vessel generally occurs in the region of the support. In the case of twin-saddle-supported horizontal vessels used for liquid storage under modest operational pressure, the strain on the inside surface of the vessel, at the top of the support, is tensile. This can create problems in glass-reinforced plastic (GRP) composite vessels since local cracking of the inner surface may allow liquid ingress to the glass through the matrix with consequent premature local failure. This paper extends the earlier work done at the University of Strathclyde, Glasgow, on metallic vessels (assumed isotropic) and outlines a thin-shell analysis, appropriate for the layered GRP vessel, to derive the strain levels in the support region. Over several years experimental work has been carried out on a range of GRP vessels of various sizes. Of particular note three full-size GRP vessels have been extensively strain gauged and hydraulically tested to provide experimental results to validate the theoretical analysis. Using this analysis, a parametric survey has been conducted and a design approach presented, to enable the maximum strain to be determined for the symmetric laminated horizontal vessel.
On the Stresses at Arrays of Oblique Holes in Thick Plates under Equi-Biaxial in-Plane Loading
Authors: Stanley P , Day B V
Published: February 2007

Previous work is reviewed, emphasis being given to the results of a photoelastic investigation of a series of hole arrays in thick plates subjected to uniaxial loading. The design of the tested arrays and their relationship to the principal features of a square array of penetrations in a part-spherical pressure vessel end are explained. Stress indices resulting from equi-biaxial loading in normal arrays (obliquity angle zero) and oblique arrays (obliquity angle of 45°) are obtained from the uniaxial data by superposition. Results for holes at the array boundaries and remote from the boundaries are presented and critically discussed.
Future Trends in Offshore Engineering
Authors: Patten Tom
Published: February 2007

The production of oil and gas offshore developed progressively as the onshore resources and reservoirs were pursued out beyond the low water mark. Particular characteristics of deeper water have resulted in specific and significant engineering features. There are other important issues such as legislation economics and environment that must be considered also. Future changes in offshore engineering including mechanical engineering aspects will probably reflect the recurring challenges of improved safety and cost reduction, as much as those of inadequacies in current performance and of gaps in present capabilities. Brief reference is made to some other exploited and potentially exploitable marine resources which may provide opportunities for technology transfer from the offshore hydrocarbon industry.
Optimal Safety System Design Using Fault Tree Analysis
Authors: Andrews J D
Published: February 2007

This paper describes a design optimization scheme for systems that require a high likelihood of functioning on demand. The final design specification is achieved by solving a sequence of optimization problems. Each of these problems is defined by assuming some form of the objective function and specifying a sub-region of the design space over which this function will be representative of the system unavailability. An example of a high-pressure protection system has been used to demonstrate the practicality of the technique. Design parameters for this system include redundancy levels, the number of elements required for a voting system to function, component selection options and maintenance inspection intervals. Both implicit and explicit constraint forms have been used in the example. The implicit constraints require a full system analysis to determine whether the current design is feasible or not. All system assessments have been carried out using fault tree analysis.
Project-Specific Software for Offshore Emergency Shutdown Systems
Authors: Borer J R , Reynolds A J
Published: February 2007

New legislation following the Piper Alpha disaster has highlighted the unsatisfactory state of programmable equipment system (PES)-based emergency shutdown (ESD) systems for offshore installations. As in the nuclear generation industry, concern is being expressed for the quality of software, particularly project-specific or application software for these systems. The defence-in-depth approach adopted by the nuclear industry is impracticable for the offshore industry and new techniques for design and implementation of the project-specific software of ESD systems are urgently required.
The Design and Analysis of a Quick-Release Pressure Vessel Door Closure
Authors: Smith B , Hyde T H , Casey G A , Warrior N A
Published: February 2007

A quick-release door closure design (Bandlock 2) is described. The paper presents a case study of the design and analysis of an existing closure geometry. Four techniques for stress analysis of the closure are described: two numerical (finite element and boundary element) an experimental (electrical resistance strain gauge) and an approximate (strength of materials) approach to the calculation of stresses. The stress results are presented in an unnormalized form for an ANSI class 600 test pressure.
Continuous External Train Noise Measurements Through an On-Board Device
Authors: Bracciali A , Ciuffi L , Ciuffi R , Rissone P
Published: February 2007

This work shows the results of a series of external noise measurements made on board a high-speed train. The tests were carried out using a specially designed device to be bolted to the axlebox of a carriage or locomotive protecting a microphone placed at a short distance in front of a single wheel. The philosophy of such a device is explained and the criteria regarding its design, the laboratory tests carried out on the device, its application to Italian State Railway's ETR500 train and the results obtained in various trials are reported. The reliability and repeatability of the results are analysed.
Brake Blending
Authors: Leigh M J
Published: February 2007

This paper reviews all forms of dynamic braking and their interactions with friction brake. The paper then goes on to look at the advantages of the schemes employed to date. Consequently, other possibilities are reviewed and considered for a variety of applications. In considering the way forward the paper reflects on the increasing use of unit trains and all data highways.
Life Cycle Cost Procurement of Swedish State Railways' High-Speed Train X2000
Authors: Akselsson H , Burström B
Published: February 2007

After thorough investigations Swedish State Railways (SJ) in 1981 decided to start the process of acquiring a high-speed train. It was also decided that the life cycle cost technique should be used. This paper gives a short introduction to the life cycle cost technique and describes the acquisition of the high-speed train from prestudy, through request for proposals, contracting, design and finally operational verification. Some experience obtained from the supplier's design work and from SJ's initial operation of the system is also outlined, as well as the outcome of the verification. The project has been a success, and both parties—SJ as customer and ABB as supplier—are convinced that the use of life cycle cost methodology has greatly contributed to this.
The Development of Friction Pairs for Intermediate to Very High Duty Railway Applications
Authors: Dolbear K D , Watson J C
Published: February 2007

Railway vehicle service speeds are set to increase from the present 300 km/h. These developments are being spearheaded by the French, German, Italian and Japanese railways. It is also clear in other less glamorous areas such as freight and suburban operations, that the trends in vehicle design are going to put severe burdens on the braking technology available today. These initiatives included the advanced suburban bogie for British Railways. While it will be possible to squeeze some further improvements out of conventional products, it has become essential to initiate work on new materials which not only meet the immediate demands but address the requirements of the middle- and long-term. Some proposals such as carbon/carbon may be impractical from a cost point of view on anything other than exotic high-speed vehicles but studies involving ceramic to ceramic interfaces are proving interesting with a real possibility of providing high performance at an economical cost for a large spread of applications. The paper will discuss some of the challenges and opportunities to be grasped and solved.
Bogies, Suspensions and Ride Quality
Authors: Rollin D
Published: February 2007

This paper discusses the commercial importance of ride quality to the InterCity traveller and describes current technical developments and their application. Options of improving ride quality of existing vehicles are outlined together with the developments in active suspensions which will be needed by the next generation of high-speed vehicles for operation on existing tracks. The author concludes by considering the likely impact on bogie and suspension specific specifications as a result of the separation of technical and commercial responsibility for track and trains currently underway in a number of European countries.

For the business engineer, ride quality is a commercial requirement which must be translated into a performance specification. This immediately raises the question, ‘How can ride quality be defined so that engineering parameters reflect the perceptions and aspirations of the customer?’
Predicting the Strength of Fibrous Composites by an Orthotropic Generalization of the Maximum-Shear-Stress (Tresca) Criterion
Authors: Hart-Smith L J
Published: February 2007

It is shown that the strength of fibrous composite laminates has not been well represented by the innumerable abstract mathematical theories for anisotropic elasticity. Only a fibre, a matrix, or the interface can fail; not the ‘lamina’ which is a useful concoction for establishing the elastic constants only. The classical maximum-shear-stress failure criterion for ductile metals is extended to include orthotropic materials like carbon fibres. The greatest differences with respect to past theories are found for biaxial loads, both when the load is of the same sign as well as of the opposite. A comparison with available test data is included.
The Role of Material Modelling Techniques in Stress Analysis and Life Assessment of Modern Aero-Engine Components
Authors: Harrison G F
Published: February 2007

Aero-engine components evolve through an iterative process involving the creation of the basic design to meet the performance requirements and the stress analyses and subsequent life evaluation of the individual components. A progressive increase in stage loading has resulted in more parts experiencing time as well as cycle dependent damage processes. The influence of cyclic softening in quantifying this effect is discussed. The implications of a fracture mechanics based damage tolerance approach in determining the lives of service discs is examined. The role of three-dimensional creep analysis, including the influence of transient thermal stress, in identifying critical areas in highly cooled rotor blades is discussed. Finally an approach for modelling anisotropic single crystal materials is illustrated.
The Efficient Computation of the Vibration Response of an Aero-Engine Rotor-Damper Assembly
Authors: Levesley M C , Holmes R
Published: February 2007

This paper deals with the application of the so-called Harmonic Balance method to the problem of determining the non-linear vibration response of a rotating assembly comprising a rotor, flexible bearing housing and oil film damper. For the latter, due consideration is given to the effects of oil supply pressure, film rupture pressure and end sealing. The paper concludes with some comments on the subject of optimizing a damper to fulfil a given purpose.
Revitalization of Chadderton: The Evolution of a Modern Aerostructures Business
Authors: Wilson D
Published: February 2007

Over the last five years, an exciting transformation has been taking place at British Aerospace's Chadderton facilities at Greengate, just inside the Oldham Borough boundary. A large and complex manufacturing organization has been transformed from a programme-driven cost centre to an autonomous business unit, operating within the British Aerospace corporate structure.

Developments at the Chadderton plant are setting the pace in a fast-changing industry. A frank and honest evaluation of the competences and strengths has been essential, and this has led to the development of strategies to achieve world-class benchmark performance. The process has been a necessary evolution to catch up and overtake the competition; it has also been traumatic and exciting, and demonstrates the potential that exists in our traditional manufacturing businesses.
Assessing the Capability of Doppler Global Velocimetry to Measure Vortical Flow Fields
Authors: Meyers J F , Miller L Scott
Published: February 2007

A new non-intrusive flow diagnostics instrumentation system, Doppler global velocimetry, is presented. The system is capable of making simultaneous three-component velocity measurements within a selected measurement plane at video camera rates. These velocity images can provide the researcher with spatial and temporal information about the flow field in a global sense. The investigation of a vortical flow above a 75° delta wing comparing standard three-component fringe-type laser velocimetry measurements with Doppler global velocimetry measurements is presented.
A Microcomputer-Based Infant Pulmonary Function System for Determination of Forced and Passive Expiratory Flow-Volume Curves: Technical Aspects
Authors: Wong E M C , Ho T F
Published: February 2007

The development of an infant pulmonary function system for medical application is important in providing a clear in depth understanding of the physical and mechanical functioning of the lung of an infant. Forced and passive expiratory flow-volume curves convey useful information about pulmonary functions. This information can be used to monitor the early development of the lungs and detect any respiratory disorders in infants. Research into various techniques to obtain these curves has shown significant progress. In this study, a microcomputer-based system was designed and built to enable these techniques to be more efficiently and accurately implemented. This paper describes the system developed to automate the test procedures, obtain the flow-volume curves, analyse test data and store results conveniently. Lastly, system performance is also discussed.
Modelling Muscle and Joint Forces at the Glenohumeral Joint: Overview of a Current Study
Authors: Runciman R J , Nicol A C
Published: February 2007

A biomechanical model of the glenohumeral joint has been developed to investigate muscle and joint loading during real life three-dimensional activities. Based on a rigid body mechanics approach, the model incorporates algorithms to correct for curved muscle paths and bone geometry, providing realistic muscle orientation over a wide range of limb positions. An optimization routine has been incorporated, minimizing overall maximum muscle stress in the 26 individual muscle elements considered. The model utilizes anatomical muscle and bone data, subject anthropometric data, kinematics measured using a six-camera Vicon motion analysis system and hand loading measured using a force-plate and mobile six-component strain gauged force transducer developed for this project. A study of real life three-dimensional activities has been conducted using five fit male subjects. Normalized, averaged muscle and joint loading have been calculated for each activity. Muscle activation appears in good agreement with published electromyographic studies. Overall joint compressive and shear forces of up to 5 and 1.5 times body weight respectively have been calculated.
Influence of the Embedding Media on the Results of Standard In Vitro Fatigue Tests on the Femoral Components
Authors: Viceconti M , Toni A , Giunti A
Published: February 2007

The aim of the present investigation was to determine the effects of the embedding material mechanical properties on the in vitro fatigue endurance of femoral hip stems as determined following ISO standards. Acrylic cements are usually employed as embedding media; due to the high cost of surgical cements, acrylic cements for dental applications are commonly used. Two acrylic cements for dental applications were tested to determine their static mechanical properties and compared with those found for three surgical cements. The same two dental cements were also compared as embedding media in a series of ISO 7206/3 fatigue tests on a mini-size Cr-Co stem; prosthesis stress analysis using strain gauges was also performed. The mechanical tests on the different cements showed that behind the definition of acrylic cement are materials with considerably different mechanical static properties. The fatigue campaign confirmed the influence of embedding media on the results obtained from the ISO 7206/3 fatigue test. Under a load of 4200 N the stem failed after four million cycles when using one cement; it did not fail after ten million cycles when using another cement. Stress analysis with strain gauges substantially confirmed these findings.
Three-Dimensional Geometrical Models of Human Knee Ligaments
Authors: Zavatsky A B , O'Connor J J
Published: February 2007

The extension to three dimensions of a two-dimensional geometrical model of the human knee cruciate ligaments is presented in this paper. As a first approximation, the ligament attachment areas on the bones are taken to be elliptical in scrape and a mapping of ligament fibres from tibia to femur is specified. Methods for calculating and illustrating ligament shape changes and fibre length changes are described, and examples of the model calculations for the knee movements of passive flexion and anterior tibial translation are given. Analysis of the results reveals that the proposed, simple extension of the two-dimensional ligament model to three dimensions is partly satisfactory for the anterior cruciate ligament, but inadequate for the posterior cruciate ligament.
Improved Trajectory Planning using Arbitrary Power Polynomials
Authors: Kirecci A , Gilmartin M J
Published: February 2007

Increasing demands for higher operational speeds, the need for flexible machinery and recent developments in microchip technology have made programmable machine systems an attractive alternative to conventional systems. However, some difficulties still remain for proper control of programmable systems, especially at higher speeds. These can be categorized into two groups: trajectory planning and trajectory tracking. Conventional trajectory planning methods are ineffective for general application, especially when velocity and acceleration conditions are included. There are many mathematical functions but polynomials are shown to be the most versatile for trajectory planning; however, these can give curves with unexpected oscillations, commonly called meandering. Tracking of a motion in this situation could engender severe practical problems. In this study, a new interpolation method using polynomials with arbitrary powers is proposed to overcome this disadvantage.
Design of High-Speed Process Machinery Transmissions in Order to Maximize the Benefits of Servo Drives
Authors: Seaward D R , Vernon G W
Published: February 2007

This paper addresses the many issues which confront a designer of a process machine when independent servo-drives are to be incorporated. Actuators which meet process requirements and which maximize servo-drive potential are described. Design and selection criteria for all elements of the total transmission system are discussed: servo-motors, feedback devices, control loop strategies, couplings, gearboxes, transmission belts, motion profiles and control computer systems. The paper draws upon a practical system which incorporated ten servo-drives cycling at 13 Hz with positional accuracies of 0.4 mm at 2.1 m/s.
Application of Front End Control in Time-Delayed Plants
Authors: Nagarajan R , Sajed K A
Published: February 2007

The front end (FE) control was recently reported as an alternative solution to a class of set-point control problems. Initial experiments with a pneumatic pick and place robot arm showed that FE control has a distinct advantage over conventional set-point control in achieving a high quality of system response in terms of time domain specifications. This has motivated further applications and analysis of FE control systems. This paper presents an adaptive FE control scheme for a class of time-delayed systems having unknown gains. The proposed scheme, when employed in controlling a repetitively operated thermal process, exhibits appreciable improvements in the quality of response compared with the conventional on/off adaptive control scheme.
Fault Detection for a Class of Unknown Non-Linear Systems via Associative Memory Networks
Authors: Wang H , Brown M , Harris C J
Published: February 2007

This paper presents a novel approach for the detection of faults for a class of non-linear systems whose parameters are unknown non-linear functions of both the measurable operating point and the faults of the system. Neural networks are used to estimate the healthy model's parameters, based on the measurable operating points, when no fault occurs within the system (this procedure is called the training of a healthy system). For this purpose, a modified version of the recursive least-squares algorithm with normalized signals and an output-error dead zone are employed. After the training of the healthy system, this recursive algorithm remains on-line to estimate the system parameters which, together with trained neural networks, are used to recognize, and differentiate, parameter changes that are caused either by the variation in the measured operating points or by faults.
Decentralized and Hierarchical Control of a Class of Robot Manipulators
Authors: Osman J H S , Roberts P D
Published: February 2007

This paper is concerned with the design of robust controllers for uncertain non-linear robot manipulators based on a deterministic approach. A decentralized tracking controller is presented in which the controller is designed for each subsystem based only on its local states. For the cases in which the interconnection functions between the subsystems are large, a two-level hierarchical control strategy is proposed. In designing the controllers, only the bounds on the system uncertainties are assumed to be known. It is shown theoretically and through computer simulations that the proposed controllers guarantee uniform ultimate boundedness of the error between the reference trajectory and the system output.