bluuebunny/crossref_metadata_2025 huggingface dataset:
Warming automotive catalysts with pulsating flows
Authors: Benjamin S. F. , Roberts C. A.
Published: October 2002

Temperatures of an automotive catalyst substrate warmed by convection pre-light-off have been measured. Direct comparison has been made of warm-up by steady and pulsating flow for a one-dimensional flow case. The 32 Hz pulsating mass flow did not feature flow reversal. Pulsations were achieved by interruption of the airflow by a rotating disc. Very small differences between steady and pulsating cases were observed because the effect of mass flow pulsations on heat transfer is minimal. Two different computational fluid dynamics methods were used to predict temperature. A one-dimensional porous medium model, which required input of an assumed heat transfer coefficient, was compared with a single-channel model. Predictions agreed closely and there was also qualitative agreement with measurements. Similar mass flow pulsations in the range 32-100 Hz have been studied for a case with a larger diameter automotive catalyst supplied via a conical diffuser. The radial flow distribution is controlled by pulsation frequency and the effect of frequency on temperature at different depths in the substrate was observed experimentally. Pulsations will affect catalyst warm-up in practical systems because of their effect on flow distribution, rather than on heat transfer.
Application of wavelet packets algorithm to diesel engines’ vibroacoustic signature extraction
Authors: Zou J , Chen J , Geng Z. M.
Published: October 2002

Multisource unstable impulsive excitations, time-varying transmission path, concentrated mode, dispersion and reverberation that are important characteristics of reciprocating machines such as diesel engines result in wide-band non-stationary vibroacoustic responses which influence the effective extraction of vibroacoustic signatures and become a key factor limiting diesel engines’ vibration diagnosis. In this paper, a serial theoretical deduction of the unstable dynamic properties of diesel engines is made; the mechanism of non-stationary vibroacoustic responses is elucidated. On that basis, the wavelet packet technique is introduced into application research on diesel engines’ vibroacoustic signature extraction. The reason for the existence of frequency aliasing in the Paley series from wavelet packets’ decomposition is analysed, and the wavelet packet frequency-shifting algorithm is given. The given algorithm can reduce the noise significantly, can heighten signal-to-noise ratio and can effectively extract the desired parameter. Experiments on 190 serial diesel engines confirm its significant validity in vibroacoustic signature extraction and reciprocating machines’ vibration diagnosis.
Mathematical modelling of catalytic exhaust systems for EURO-3 and EURO-4 emissions standards
Authors: Pontikakis G , Stamatelos A
Published: October 2002

The application of computer simulation in the development of catalytic exhaust aftertreatment systems for cars is over thirty years old. However, ever-increasingly stringent exhaust emissions legislation requires an ever-increasing degree of accuracy and complexity in the mathematical models applied. Traditionally, the Langmuir-Hinshelwood kinetics were applied in the majority of the models available, with a small number of representative chemical reactions. In this paper it is proved, by means of typical case studies, that the above modelling approach, with the necessary refining, can be brought to the level of accurately predicting the behaviour of advanced catalyst systems employed in EURO-3 and EURO-4 emissions homologation. An essential characteristic that was introduced to this end is the computer-aided selection (best fit) of the tunable parameters representing the apparent chemical kinetics and oxygen storage and release properties of each different catalyst-washcoat combination. Other modelling improvements are also discussed in the present paper, setting the scene for high accuracy simulations in view of the current and future emissions standards for spark-ignited, diesel and gasoline direct injection (GDI)-engined vehicles. These include the modelling of the aged catalyst, as well as taking into account the effect of precious metal loading variation on the apparent kinetics.
Electrohydraulic effects on the modelling of a vehicle active suspension
Authors: Watton J , Holford K. M. , Surawattanawan P
Published: October 2002

A car suspension incorporating a Lotus actuator and a TVR suspension/wheel unit is studied both experimentally and analytically. An emphasis is placed on hydraulic modelling using a series of transfer functions linking the hydraulic and suspension components. This is significantly aided by the use of a Moog 2000 programmable servo controller (PSC) to equalize the extending and retracting flow gains of the servovalve in the Lotus actuator control loop, justifying the use of combined extending and retracting transient data for parameter identification. This then allows the system equations to be developed using linear state-space theory, and a suitable form is proposed for further design studies. It is shown that the hydraulic components significantly contribute to the system dynamics and hence cannot be neglected when control schemes are formulated. In particular, the significance of hydraulic bulk modulus on dynamic performance is evaluated, and the importance of accurately determining all components of velocity-type damping is highlighted.
A vehicle control algorithm for stop-and-go cruise control
Authors: Yi K , Hong J , Kwon Y. D.
Published: October 2002

A vehicle speed and vehicle-to-vehicle distance control algorithm for vehicle stop-and-go cruise control has been proposed in this paper. The control algorithm consists of speed and distance control algorithms and a combined throttle-brake control law. Linear quadratic optimal control theory has been used to develop a vehicle speed and distance control algorithm. A desired acceleration for the vehicle has been designed on the basis of the vehicle speed and distance control algorithm. Throttle and brake actuators are controlled by the throttle-brake control law so that the vehicle acceleration tracks the desired acceleration. A stepper motor and an electronic vacuum booster have been used for the throttle and brake actuators respectively. The throttle and brake actuators have been tested and the actuator dynamics has been incorporated in the simulation package used in this study. The effects of the model errors and the actuator dynamics on the control performance have been investigated via simulations. It has been shown that the proposed control law provides good performance over the model errors and the actuator dynamics.
New algorithm and accelerometer locations for frontal crash discrimination
Authors: Jeong H-Y , Kim Y-H
Published: October 2002

Several crash discrimination algorithms have been developed in order to have timely air bag deployment during frontal crashes. However, it is still challenging to have timely air bag deployment, especially during pole, underride, oblique and offset crashes. Therefore, in this paper, a new algorithm for frontal crash discrimination is proposed, with the summation of the absolute value of the deceleration change being used as a metric and with the metric and its threshold being processed as a function of the velocity change. The new algorithm was applied to frontal crashes of a minivan and a sports utility vehicle, and it resulted in timely air bag deployment for frontal crashes, including pole, underride, oblique and offset crashes. Moreover, it is proposed that an accelerometer be installed on each side of the rockers or pillars to assess the crash severity of each side and to deploy driver and passenger air bags at different times, especially during an asymmetric crash such as an oblique and an offset crash. As an example, the deceleration signals measured at the left and right B-pillar/rocker locations were processed through the algorithm, and earlier time-to-fires (TTFs) were obtained for the air bag on the struck side than for the air bag on the non-struck side.
Detailed analytical model of a single-cylinder diesel engine in the crank angle domain
Authors: Zweiri Y. H. , Whidborne J. F. , Seneviratne L. D.
Published: October 2002

A detailed analytical non-linear dynamic model for single-cylinder diesel engines is developed. The model describes the dynamic behaviour between fuelling and engine speed and includes models of the non-linear engine and dynamometer dynamics, the instantaneous friction terms and the engine thermodynamics. The model operates in the crank angle domain. The dynamometer model enables the study of the engine behaviour under loading. The instantaneous friction model takes into consideration the viscosity variations with temperature. Inertia variations with piston pin offset are presented. In-cycle calculations are performed at each crank angle, and the correct crank angles of ignition, speed variations, fuel supply and air as well as fuel burning rate are predicted. The model treats the cylinder strokes and the manifolds as thermodynamic control volumes by using the filling and emptying method. The model is validated using experimentally measured cylinder pressure and engine instantaneous speeds, under transient operating conditions, and gives good agreement. The model can be used as an engine simulator to aid diesel engines control system design and fault diagnostics.
Dynamic modelling and simulation of two-mode electric variable transmission
Authors: Zhang D , Chen J , Hsieh J , Rancourt J , Schmidt M. R.
Published: October 2002

A dynamic model is created for evaluating an electric variable transmission (EVT) developed by Allison Transmission Division of General Motors. The model is based on Kane's equations, and the concept of generalized velocity is used. Mechanical losses were considered. The performance of the EVT was simulated using the model. The capacities of the transmission output power and torque while the engine is running on the best fuel economy curve for a given two-mode EVT system are investigated. The operating behaviours of the electric units (motors/generators) are also studied. The results show an effective way to evaluate the EVT design concept.
Orange peel: Who cares?
Authors: Love J. C. , Smith G. F. , Pharaoh M , Coates R
Published: October 2002

Each year, automotive manufacturers spend the equivalent of millions of pounds sterling on measuring the paint surface defect known as ‘orange peel’. This paper uncovers the near invisibility of orange peel to customers and questions the need for this expenditure on on-line orange peel measurement. Face-to-face survey techniques were used to establish that customers either did not perceive the paint feature known as orange peel as detrimental to a surface or could not differentiate between surfaces with differing amounts of orange peel. This leads to the suggestion that assumptions made about the need to measure orange peel could be examined, and, if measurement is found to be unnecessary, costs in the automotive industry could be reduced.
Fuzzy neural ignition timing control for a natural gas fuelled spark ignition engine
Authors: Wang W , Chirwa E. C. , Zhou E , Holmes K , Nwagboso C
Published: October 2002

One of the important inputs to a spark ignition engine which affects nearly all engine outputs is ignition timing. It is well known that the optimum ignition timing which gives the maximum brake torque for a given engine design varies with the rate of flame development and propagation in the cylinder. Modern engines show ignition timing being generally controlled by fixed open-loop schedules as functions of engine speed and load. It is desirable that this ignition timing can be adjusted to the optimum level which produces the best torque to obtain minimum fuel consumption and maximum available power. This paper presents an ignition timing control system based on fuzzy logic and neural network theories. A fibre optical sensor system was developed for measurement of the intensity of the luminous emission which correlates the combustion pressure and ignition timing control on a Ford 1600 cm3 four-cylinder spark ignition engine fuelled with natural gas. Several engine tests were carried out in optimizing the combustion intensity detection system. The results obtained provide important information compatible with intelligent control of the engine using fuzzy neural control technology. Moreover, tests carried out with data using this technology show good results that fit quite well with the original engine output torque characteristics.
A simulation study of the control algorithm for a ball screw type motor-driven power steering system
Authors: Yun S. C. , Cho N. G. , Han C. S.
Published: October 2002

The power steering system for vehicles is becoming essential for supporting the driver's steering efforts, especially for manoeuvring in parking lots. Although hydraulic power steering has been widely used for years, it is not efficient enough. The problems associated with a hydraulic power steering system can be solved by using a motor-driven power steering (MDPS) system. In this study, a dynamic model and a control algorithm for a ball screw type MDPS system have been derived and analysed by using discrete modelling technology. To improve the comfort level while steering and power steering characteristics, an additional scheme is added to the conventional power boosting control algorithm. Through simulations, the effects of the control gain on the steering angle gain in the frequency domain were verified. The steering returnability and steering torque phase lag in on-centre handling tests were also verified.
Active wheel steering and yaw moment control combination to maximize stability as well as vehicle responsiveness during quick lane change for active vehicle handling safety
Authors: Mokhiamar O. , Abe M.
Published: October 2002

The aim of this paper is not only to present various methods for combining lateral force and yaw moment control but also to find out how the mix between them should be applied to maximize the stability limit as well as vehicle responsiveness. Approximated two-degree-of-freedom (2DOF) vehicle model responses of side-slip angle and yaw rate are used to introduce the required total lateral force and yaw moment control. Three different cases of combining lateral force and direct yaw moment control have been investigated using computer simulations. A direct yaw moment control to follow the yaw rate response only is taken as a comparison case in order to show the effect of the combined control on vehicle stability and responsiveness. A computer simulation of a closedloop driver-vehicle system subjected to quick lane change with braking is used to prove the influence of the combined control. It is found that the influence of the combined control on vehicle stability and responsiveness is significant.
Effects of weigh-in-motion errors on pavement thickness design
Authors: Collop A. C. , Hakim B. Al. , Thom N. H.
Published: October 2002

This paper investigates errors associated with weigh-in-motion (WIM) measurements using data from 15 Department of the Environment, Transport and the Regions (DETR) WIM systems operated on motorways and trunk roads in England. Three sources of error have been identified: calibration errors, random sensor error and dynamic load effect. The 5-95 percentile range and the standard deviation of the calibration errors were found to be 30 and 11 per cent respectively. The average value of the random sensor error plus dynamic load effect was found to be 11 per cent. The effects of these errors on pavement design traffic and subsequent pavement thickness design have been investigated. It is found that, using a fourth power law, the effect of sensor/dynamic and calibration errors is likely to overpredict the traffic by typically between 15 and 20 per cent, which would result in a 5-15 mm overdesign of pavement thickness for typical flexible pavement structures.
A feasibility study on elastokinematic parameter identification for a multilink suspension
Authors: Rocca E , Russo R
Published: October 2002

In this paper an algorithm for the kinematic analysis of a multilink suspension taking joint compliance into account is presented. The analysis can be pro. tably used in an identi. cation procedure to determine elastokinematic parameters starting from experimental data. The proposed identification algorithm is based on the solution of a typical non-linear least-squares problem. Inorder to test the feasibility of this procedure, a multilink suspension, modelled by a multibody dynamics code, is employed as the experimental data source. Some joint stiVness values are determined to provide an example of the algorithm's application.
Modelling of a pressure wave supercharger including external exhaust gas recirculation
Authors: Weber F , Guzzella L , Onder C
Published: October 2002

This paper presents a mean value model of a pressure wave supercharger together with a spark ignition engine including external exhaust gas recirculation. The model of the pressure wave supercharger is based on linear one-dimensional gas dynamics. It includes an approach for the mixing zone between exhaust gases and fresh air which permits the calculation of the exhaust gas recirculation rate within the charger. The mass flow of the recirculated exhaust gas is the combined effect of too large an exhaust gas penetration into the cell wheel of the charger and of incomplete scavenging of the cell wheel. The model of the pressure wave supercharger is validated by the identification of four physically based model parameters and shows an error smaller than 5 per cent over the operating range investigated. The model can be integrated into an overall engine system model which predicts transient exhaust gas recirculation effects during load steps with good accuracy. The system model demonstrates that exhaust gas recirculation during transients is mainly caused by incomplete scavenging of the cell wheel and not by the exhaust gas penetration into the cell wheel being too large. Both the model of the pressure wave supercharger and the overall engine system model are validated by steady state and transient measurements on a dynamic test bench.
Multiple-bump roadholding test: Description and metric interpretation
Authors: Norman K D
Published: October 2002

Road vehicle roadholding comprehends directional response to road inputs. This response is primarily a function of the roadway's frequency content and amplitude and the vehicle's inertial, suspension and tyre characteristics. There is also evidence that suspension kinematic and compliance steer properties can have a significant contribution (Rill, G. Steady state cornering on uneven roadways. SAE paper 860575, 1986). The multiple-bump roadholding test measures vehicle response to a periodic bump of varying frequency while cornering. By driving a vehicle at different speeds over a set of periodic bumps placed on circles of different diameters, it is possible to observe the response to different fundamental bump excitation frequencies at a particular lateral acceleration. This paper describes the test procedure, measured vehicle responses and the metrics calculated.
On the need for bump event correction in vibration test profiles representing road excitations in automobiles
Authors: Steinwolf A , Giacomin J A , Staszewski W J
Published: October 2002

This paper presents an approach to the synthesis of compressed vibration test profiles representing much longer time histories obtained in road testing of ground vehicles. Vibration test profiles are defined as those related directly to operational testing on specific road surfaces and which summarize the input to the vehicle in the given conditions. The method extends the classical Fourier transform technique by means of bump event correction in the background Fourier signal where the bump event term implies a high amplitude transient event of the shock type. The orthogonal wavelet decomposition was used as a specific filtering tool facilitating bump event identification. Examples of seat guide vertical acceleration have been considered. Calculated probability density functions suggest the ability of the bump correction method to improve the statistical accuracy of the final vibration test profile with respect to the original road data. Test profiles obtained by means of Fourier transform synthesis with subsequent re-insertion of bump events from separated frequency bands were more accurate than those obtained by Fourier synthesis alone. Further developments led to advanced bump re-insertion with synchronization of events occurring in different frequency bands at the same moment of time. Test profiles generated in this way have provided better accuracy compared with the non-synchronized algorithm.
The on-line detection of engine misfire at low speed using multiple feature fusion with fuzzy pattern recognition
Authors: Liu S , Gu F , Ball A
Published: October 2002

This paper proposes a technique for the online detection of incipient engine misfire based on multiple feature fusion and fuzzy pattern recognition. The technique requires the measurement of instantaneous angular velocity signals. By processing the engine dynamics model equation in the angular frequency domain, four dimensionless features for misfire detection are defined, along with fast feature-extracting algorithms. By directly analysing the waveforms of the angular velocity and the angular acceleration, six other dimensionless features are extracted. Via fuzzy pattern recognition, all the features are associated together as a fuzzy vector. This vector identifies whether the engine is healthy or faulty and then locates the position of a misfiring cylinder or cylinders if necessary. The experimental work conducted on a production engine operating at low speeds confirms that such a technique is able to work with the redundant and complementary information of all the features and that it leads to improved diagnostic reliability. It is fully expected that this technique will be simple to implement and will provide a useful practical tool for the online monitoring and realtime diagnosis of engine misfire in individual cylinders.
Impact throw model for vehicle-pedestrian collision reconstruction
Authors: Han I , Brach R M
Published: October 2002

A planar model for the mechanics of a vehicle-pedestrian collision is presented, analysed and compared with experimental data. It takes into account the significant physical parameters of wrap and forward projection collisions and is suitable for solution using mathematics software or spreadsheets. Parameters related to the pedestrian and taken into account include horizontal distance travelled between primary and secondary impacts with the vehicle, launch angle, centre-of-gravity height at launch, the relative forward speed of the pedestrian to the car at launch, distance from launch to a ground impact, distance from ground impact to rest and pedestrian-ground drag factor. Vehicle and roadway parameters include post-impact, constant velocity vehicle travel distance, continued vehicle travel distance to rest with uniform deceleration and relative distance between rest positions of vehicle and pedestrian. The model is presented in two forms. The first relates the throw distance to the initial vehicle speed. The second, intended for reconstruction, relates the vehicle speed to the pedestrian throw distance. The first form is used as means of comparison of the model with selected sets of experimental data taken from the current literature, including a variational study using Monte Carlo simulation. The second (reconstruction) form is derived analytically not empirically and the parameters have physical interpretations. In order to obtain parameter values, direct calculation or the method of least squares can be used. A comparison of the reconstruction model with results of other reconstruction models is presented.
Reliability-based design of automobile components
Authors: Zhang Y , Liu Q
Published: October 2002

Techniques from the perturbation method, the second moment and reliability-based design theory are employed to present a practical and effective method for the reliability-based design of automobile components. The theoretical formulae of reliability-based design of automobile components. are obtained. The reliability-based design methods are employed to develop the reliability design of automobile axles and springs. The corresponding program can be used to obtain the reliability- based design parameters of automobile components accurately and quickly.
Effects of atmospheric temperature and pressure on the performance of a vehicle
Authors: Soares S M C , Sodre J R
Published: October 2002

This paper describes the influence of the atmospheric conditions on the performance of a vehicle. Tests were carried out on the road, under different conditions of ambient temperature, pressure and humidity, measuring the acceleration time. The tested vehicle featured a gasoline-fuelled four-cylinder engine, with variable intake manifold length and multipoint fuel injection. The vehicle was tested at sea level and at an altitude of 827 m above sea level, with the ambient temperature ranging from 20 to 30°C. The times required for the vehicle to go from 80 to 120 km/h, from 40 to 100 km/h and to reach distances of 400 and 1000 m leaving from an initial speed of 40 km/h at full acceleration were recorded. The results showed the vehicle performance to be more affected by changes in the atmospheric pressure than in the temperature. An average difference of 3 per cent in the time to reach 1000 m, leaving from the speed of 40 km/h at full acceleration, was found between the atmospheric pressures tested, for a fixed temperature.
Emissions performance of Korean vehicles with different vehicle specification, mileage and fuel
Authors: Ryu J , Song J
Published: October 2002

This study investigates the effect of vehicle mileage, vehicle characteristics and the fuels on exhaust gas performance. In order to research this topic, 1260 vehicles with spark ignition engines and 960 vehicles with compression ignition engines were sampled and surveyed. The exhaust emissions are measured with a CO-hydrocarbon (HC) emission gas analyser and a filter-type smoke analyser. The results show that the amount of emission gas is not directly related to the mileage covered by the vehicle. However, the engine specifications, such as valve train type or air induction type, influence emissions. In addition, the liquid petroleum gas (LPG) vehicles emit more CO and HC than gasoline vehicles, although it is widely known that an LPG engine emits less exhaust. Smaller cars emit a lot of CO and HC compared with a larger car, and 1300 and 1800 cm3 displacement volume vehicles also produce higher exhaust emissions. These results indicate that new legal restrictions are required and more research on reducing emissions is needed.
Development of cavitation and enhanced injector models for diesel fuel injection system simulation
Authors: Lee H-K , Russell M F , Bae C S , Shin H D
Published: October 2002

To expedite the application of fuel injection equipment to diesel engines, powertrain engineers are simulating the rate of injection with computer models. Many of the simple models give quite substantial errors if fuel cavitation in the high pressure system and the variations in bulk modulus with temperature and pressure are not included. This paper discuses cavitation and a companion paper discusses the treatment of non-linear bulk modulus.

Diesel fuel injection nozzle hole size has been reduced and the injection pressures have been raised, to improve combustion, and the termination of the injection has been accelerated, to reduce carbon particle mass in the exhaust. High injection pressures and rapid termination set up very large hydraulic waves in the pipes and drillings of the fuel injection system, be it pump-pipe-nozzle or accumulator/common rail in type. The fuel momentum generated in these vigorous wave actions leaves such low pressures in parts of the system that vapour bubbles form in the fuel. Cavitation changes the bulk modulus of the fuel and the collapse of the cavities imparts sudden high pressure pulses to the fuel columns in the system and changes injection characteristics significantly. When modelling devices to control injection rate, the cavitation and non-linear bulk modulus have to be incorporated into the model. To this end, the concept of ‘condensation’ has been useful. The cavitated pipe section is divided into liquid and liquid + vapour mixture columns and modified momentum and mass conservation equations are applied separately. The model has been validated with a particular application of a rotary distributor pump to a high speed direct injection diesel engine, which is one of the more difficult fuel injection systems to model in which cavitation occurs at several operating conditions. The simulation results show the cavitation characteristics very well. This cavitated flow calculation model may be applied to other one-dimensional flow systems

In addition, a more comprehensive injector model is introduced, which considers two loss factors at the needle seat and holes, sac volume, and viscous drag and leakage. This enhanced injector model shows some improvement at low load conditions
A rule-based technique for two-state switchable suspension dampers
Authors: Tavner A. C. R. , Turner J. D. , Hill M
Published: October 2002

Following the introduction of an adaptive suspension system based on two-state switchable dampers for the Ford Mondeo, a requirement arose for a damper test system. A method was needed whereby the damper switching operation could be checked during routine servicing, without removing the damper from the vehicle. A technique has been developed which allows the switching function of each damper to be assessed by analysing the response of the vehicle to a series of ‘depress and release’ tests. A displacement transducer and data logging system record the displacement—time history at each wheel of the vehicle. An algorithm has been developed which is capable of differentiating between a damper switching failure and consequent alterations in the response of the vehicle caused by coupling effects.
A comparative study of the performance and exhaust emissions of a spark ignition engine fuelled by natural gas and gasoline
Authors: Evans R. L. , Blaszczyk J
Published: October 2002

The purpose of this study was to obtain a detailed comparison of engine performance and exhaust emissions from natural gas and gasoline fuelled spark ignition engines. Each fuel was tested at both wide-open throttle and two part-load operating conditions over a wide range of air—fuel ratios. The results show that the power output of the engine at a given throttle position was reduced by about 12 per cent when fuelled by natural gas due to displacement of air by the gas. The emission levels for natural gas were lower by from 5 to 50 per cent, depending on the pollutant, compared to gasoline. On an energy basis, both fuels exhibited nearly equal thermal efficiency, except that at very lean air—fuel ratios natural gas showed increased efficiency due to an extension of the lean limit of combustion.
Technical Note: Detection of delamination in tyres using eddy currents
Authors: Gros X. E.
Published: October 2002

Non-destructive testing (NDT) is a useful tool to assess the structural integrity of components in order to maintain quality and safety standards. A low-cost electromagnetic technique based on eddy currents induced into a material appeared promising for the inspection of composite materials. Experiments were carried out in order to assess the potential of eddy currents in detecting delamination in rubber tyres. Infrared thermography was used to verify inspection results achieved with eddy currents. Non-destructive examination results are presented in this paper; these confirm that eddy current testing is an economically viable alternative for the inspection of steel reinforced truck tyres.
Characterization of automotive dampers using higher order frequency response functions
Authors: Cafferty S , Tomlinson G. R.
Published: October 2002

Automotive dampers are an important element of a vehicle's suspension system for controlling road handling and passenger ride comfort. Many automotive dampers have non-linear asymmetric characteristics to accommodate the incompatible requirements between ride comfort and road handling, thus the ride comfort engineer requires techniques that can characterize this non-linear behaviour and provide models of the dampers for use in ride performance simulations of the full suspension system.

The work presented in this paper is concerned with developing a frequency domain technique using higher order frequency response functions (HFRFs) to characterize a Monroe automotive damper. The principal diagonals and multidimensional surfaces of the HFRFs up to third order are obtained. Non-linear damping coefficients for the damper are derived from the HFRFs and the energy transfer properties are investigated.

The results show that the majority of the HFRFs contain no peaks or resonances, indicating that the damper has no preferred frequencies for energy transfer. The accuracy of the damping coefficients determined from the HFRFs is poor. This is due to the inability of the technique to measure the pure HFRFs and separate the effects of non-linearities in the input actuator from those in the damper. It is concluded that these constraints currently impose some limit on the use of the methodology.
The meshing of timing belt teeth in pulley grooves
Authors: Childs T. H. C. , Dalgarno K. W. , Hojjati M. H. , Tutt M. J. , Day A. J.
Published: October 2002

The work described here has been carried out to obtain a better understanding of the tooth root cracking failure mode of timing belts. Previous work has demonstrated the close dependence of this on the tooth deflections of fully meshed teeth, generated by torque transmission, but has not considered the additional distortions generated in the partially meshed conditions at entry to and exit from a pulley groove. Approximate compatibility and constitutive equations are combined with a rigorous consideration of tooth equilibrium in partial meshing to show how bending moments are generated at both exit from a driven pulley and entry to a driving pulley. Experimentally determined belt lives correlate very well with a combined measure of fully meshed tooth strain and strain due to bending at entry or exit. The analysis also shows that this strain measure reduces with increasing belt tooth stiffness, confirming the importance of a high tooth stiffness for a long belt life. Tooth force variations through the partial meshing cycle have also been predicted and compared with measurements obtained from a special strain gauge instrumented pulley. A greater pulley rotation than is predicted is required for a belt tooth to seat in a pulley groove. There is room for improvement in the modelling.
A simple two-state late intake valve closing mechanism
Authors: Bassett M. D. , Blakey S. C. , Foss P. W.
Published: October 2002

The late intake valve closing (LIVC) load control concept provides a means to eliminate most of the pumping work energy loss. Experimental and theoretical studies have shown that the fuel saving with such a load control system can be as much as 7 per cent. If LIVC is combined with a variable compression ratio (VCR) device, further fuel savings can be realized. Results of up to 20 per cent over a conventional engine, at low loads/speeds have been reported. A simple two-state LIVC control mechanism is currently under development/evaluation at Sheffield Hallam University.
Sensing tyre pressure, damper condition and wheel balance from vibration measurements
Authors: Craighead I A
Published: October 2002

The majority of disturbance and control forces affecting a vehicle are transmitted through the tyre-ground interfaces. For optimum performance, components at each wheel station should be regularly inspected and maintained. Failure to maintain tyre pressures at correct levels results in increased tyre wear, increased fuel consumption, reduced ride comfort and degradation of vehicle handling. Worn dampers also reduce ride comfort and are detrimental to handling. Unbalanced wheels lead to vibration and wear in steering linkages.

A system is proposed which will monitor these parameters while the vehicle is being driven in the normal way. The system is based upon measuring the vertical vibration at each wheel/axle station. Subsequent signal processing enables a dashboard indication of tyre pressures, damper effectiveness and wheel unbalance to be made available to the driver.
Precoated steels development for the automotive industry
Authors: Matthews A E , Davies G M
Published: October 2002

The paper sets out to describe how it is essential that product development and implementation are undertaken on a joint partnership basis, between supplier and manufacturer from concept stage; this is to ensure that coated steels and associated substrates developed will meet the design and manufacture requirements, together with environmental considerations or recyclability and vehicle fuel economy. The co-operative efforts of the partnership are aimed at providing continuous improvements in coating technology and optimization of durability, surface treatment and manufacture for the customer in the present, medium and long term. In order to accelerate this development, a network of interactive technical information exchange was set up between British Steel Strip Products and Rover Body and Pressings, to provide faster response for ‘initial supply and evaluation of trial material’ and ‘forward planning for phased production introduction’. Environmental considerations require that precoated products can easily be recycled. This is attained in a similar way to mild steel, with certain modifications to the processing. Legislation on fuel efficiency is addressed by reducing the weight of the monocoque by improvement of torsional stiffness through weld bonding combined with thinner gauge high-strength steel panels.
A system for simulating structural intrusion in automobile full-frontal and frontal-offset crashes in the laboratory sled test environment
Authors: Bass C R , Crandall J R , Dekel E , Jordan A , Pilkey W D
Published: October 2002

A sled system capable of producing structural intrusion in the footwell region of an automobile has been developed. The system couples the hydraulic decelerator of the sled to actuator pistons attached to the toepan and floorpan structure of the buck. Characterization of the footwell intrusion event is based on developing a toepan pulse analogous to the acceleration pulse used to characterize sled and vehicle decelerations. Sled tests with the system indicate that it is capable of accurately and repeatably simulating toepan/floorpan intrusion into the occupant footwell. Test results, including a comparison of lower extremity response between intrusion sled tests and no intrusion sled tests, indicate that this system is capable of repeatable, controlled structural intrusion during a sled test impact. Test results also suggest that lower extremity forcing during footwell intrusion is significantly larger than such forcing with no intrusion, and that response and risk of injury for occupants in frontal or frontal-offset crashes are more severe.
Mathematical modelling of a thermochemical energy store: Automobile application
Authors: Darkwa K , O'Callaghan P W
Published: October 2002

An analytical evaluation of a thermochemical store for minimizing energy consumption and pollutants simultaneously from automobile engines has been carried out. The analysis of the model indicates a possibility of achieving a working temperature of a typical 2 litre petrol engine within 4 minutes. However, the viability of the model depends on addressing issues such as the life cycle of the storage material and the bed configuration of the store. Experimental validation is therefore recommended.
Operation of exhaust systems of turbocharged diesel engines identified by means of exergy analysis
Authors: Fijalkowski S , Nakonieczny K
Published: October 2002

A method and results of the analysis of exergy losses that occur in the exhaust system of a turbocharged diesel engine are presented. The aim of the work was to distinguish nodes in the system where exergy losses arise and make precise assessment of losses generated there. Losses were found to be attributable to three main sources: high velocity flow of viscous gas through variable geometry ducts; irreversibility of thermodynamic processes; and heat exchange through the walls of the exhaust system. The adopted model of generating exergy losses has made it possible to carry out a computer simulation for an exemplary turbocharged engine. The results are illustrated in diagrams and discussed.
Review Paper: Assessing ‘road-friendliness’: A review
Authors: Potter T E C , Cebon D , Cole D J
Published: October 2002

This paper is concerned with assessing the dynamic tyre forces generated by articulated heavy goods vehicles for road damaging potential. Various factors are discussed, including: (a) general testing methodologies; (b) road damage issues such as ‘spatial repeatability’ of dynamic tyre forces and road damage criteria; (c) vehicle response issues, such as test duration and sampling details, road roughness, testing speed, wheel-base filtering, tractor—trailer interaction, suspension maintenance and ‘indirect’ testing methods; and (d) implementation issues. It is concluded that the most practical method of assessment testing would be to use a ‘type approval’ test to measure the vehicle's peformance when coupled to a standard trailer or tractor unit, combined with anual inspections of hydraulic damper integrity. The type approval procedure should use simple single-axle laboratory tests to estimate the parameters of a generic mathematical model of each vehicle unit. Numerical simulations of the tractor and standard trailer (or trailer and standard tractor) should be used to determine the vehicle's response to a variety of typical road input conditions. These responses should than be assessed using realistic road damage criteria to determine an ‘in-service’ road damage index.
A neurofuzzy approach to future intelligent driver support systems
Authors: Matthews N D , An P E , Roberts J M , Harris C J
Published: October 2002

This paper reviews a variety of advanced signal processing algorithms that have been developed at the University of Southampton as part of the Prometheus (PROgraMme for European Traffic flow with Highest Efficiency and Unprecedented Safety) research programme to achieve an intelligent driver warning system (IDWS). The IDWS includes: visual detection of both generic obstacles and other vehicles, together with their tracking and identification, estimates of time to collision and behavioural modelling of drivers for a variety of scenarios. These application areas are used to show the applicability of neurofuzzy techniques to the wide range of problems required to support an IDWS, and for future fully autonomous vehicles.
Intercooler model for unsteady flows in engine manifolds
Authors: Bromnick P A , Pearson R J , Winterbone D E
Published: October 2002

A model has been developed for intercoolers which are used to reduce the temperature of the charge air in turbocharged internal combustion engines. The detailed theory for the intercooler model is presented. The behaviour of the intercooler is characterized by the relationship between the number of transfer units ( NTU) and the effectiveness (ε) of the intercooler, which is assumed to be that of a cross-flow heat exchanger. The structure of the code used to implement the model is presented and the model is applied to simulate the gas dynamics in a medium-speed turbocharged and intercooled diesel engine. The results show the predicted variation of pressure, temperature and mass flowrate across the intercooler and also the variation of intercooler effectiveness with mass flowrate.
Topological optimization of a bumper beam via the messy genetic algorithm
Authors: Duponcheele G , Tilley D G
Published: October 2002

This paper introduces a technique for certain types of topological shape optimization problems, called variable primary and full grammars, which are derived from shape grammars. An industrial application is used as an example based on the optimization of an automotive structural bumper beam. The optimizer, the messy genetic algorithm, a technique more powerful than traditional genetic algorithms, does not use any derivative information on the evolution of the shape, but only simple evaluations. This technique produces interesting new designs for bumper beams, although they are not globally optimal. These new designs have moved from crenellations to more complex topologies.
The role of computer aided engineering in the design optimization of exhaust after-treatment systems
Authors: Konstantinidis P. A. , Koltsakis G. C. , Stamatelos A. M.
Published: October 2002

The goals of employing computer aided engineering (CAE) tools have always been the improvement of product quality and the simultaneous reduction of the related time-to-market and development costs. The latter may be achieved when the optimization procedure is carried out without the need to construct and test numerous prototypes. CAE tools and methodologies, apart from the design phase, can also be employed for dedicated prediction and analysis purposes, with the intention to fully exploit the capabilities of the catalytic exhaust system.

A set of fundamental CAE tools and the accompanying (CAE) methodology, aiming to assist the design optimization of catalytic exhaust systems for spark-ignition-engined vehicles, are presented. The set comprises the following individual cooperating modules: a transient exhaust system heat transfer code, a transient three-way catalytic converter (3W-CC) computer code with an accompanying kinetics tuning procedure, a 3W-CC database and an ageing assessment methodology.

The CAE methodology may be exploited in the directions of exhaust system design and optimization, addressing the catalytic exhaust system as an entity that consists of interrelated components. In that context, specific examples of real practice are demonstrated. This methodology is already being extensively used by the authors in research and development of automotive exhaust after-treatment systems, with promising results.
A study of engine noise transmission using statistical energy analysis
Authors: Steel J. A.
Published: October 2002

This work uses statistical energy analysis (SEA) to study engine noise transmission through a small passenger motor vehicle and in order to do this the sound and vibration power input is calculated. An aim of this work is to identify the causes of differences between measured and SEA predicted vibration transmission in motor vehicles. To allow this to be studied a relatively simple running condition and vehicle are chosen. Airborne and structural paths for sound and vibration transmission to a vehicle saloon are considered. Also, SEA is used to identify the relative importance of each structural and airborne power input in relation to the sound power that is transmitted to the vehicle saloon. This technique can then make it possible for the power input matrix to be greatly simplified. The most important power input to the small passenger vehicle used in this study is found to be at the floor mounts of the engine subframe. At high frequencies resonant transmission through the firewall (dash) can also be important. The results indicate the difficulty of estimating the power input, which is the main cause of differences between measured and predicted results (even for the restricted running condition considered here). The work also demonstrates that SEA can be very useful for identifying important transmission paths and predicting overall performance.