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Sökning: L773:0954 4070 OR L773:2041 2991

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1.
  • Albinsson, Anton, 1989, et al. (författare)
  • Estimation of the inertial parameters of vehicles with electric propulsion
  • 2015
  • Ingår i: Proceedings of the Institution of mechanical engineers. Part D, journal of automobile engineering. - : SAGE Publications. - 0954-4070 .- 2041-2991. ; , s. 1-18
  • Tidskriftsartikel (refereegranskat)abstract
    • More accurate information about the basic vehicle parameters can improve the dynamic control functions of a vehicle. Methods for online estimation of the mass, the rolling resistance, the aerodynamic drag coefficient, the yaw inertia and the longitudinal position of the centre of gravity of an electric hybrid vehicle is therefore proposed. The estimators use the standard vehicle sensor set and the estimate of the electric motor torque. No additional sensors are hence required and no assumptions are made regarding the tyre or the vehicle characteristics. Consequently, all information about the vehicle is available to the estimator.The estimators are evaluated using both simulations and experiments. Estimations of the mass, the rolling resistance and the aerodynamic drag coefficient are based on a recursive least-squares method with multiple forgetting factors. The mass estimate converged to within 3% of the measured vehicle mass for the test cases with sufficient excitation that were evaluated. Two methods to estimate the longitudinal position of the centre of gravity and the yaw inertia are also proposed. The first method is based on the equations of motion and was found to be sensitive to the measurement and parameter errors. The second method is based on the estimated mass and seat-belt indicators.This estimator is more robust and reduces the estimation error in comparison with that obtained by assuming static parameters. The results show that the proposed method improves the estimations of the inertial parameters. Hence, it enables online non-linear tyre force estimators and tyre-model-based tyre–road friction estimators to be used in production vehicles.
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2.
  • Albinsson, Anton, 1989, et al. (författare)
  • Evaluation of vehicle-based tyre testing methods
  • 2019
  • Ingår i: Proceedings of the Institution of Mechanical Engineers. Part D, Transport engineering. - : SAGE Publications. - 2041-2991 .- 0954-4070. ; 233:1, s. 4-17
  • Tidskriftsartikel (refereegranskat)abstract
    • The demand for reduced development time and cost for passenger cars increases the strive to replace physical testing with simulations. This leads to requirements on the accuracy of the simulation models used in the development process. The tyres, the only components transferring forces from the road to the vehicle, are a challenge from a modelling and parameterization perspective. Tests are typically performed on flat belt tyre testing machines. Flat belt machines offers repeatable and reliable measurements. However, differences between the real world road surface and the flat belt can be expected. Hence, when using a tyre model based on flat belt measurements in full vehicle simulations, differences between the simulations and real prototype testing can be expected as well. Vehicle-based tyre testing can complement flat belt measurements by allowing reparameterization of tyre models to a new road surface. This paper describes an experimental vehicle-based tyre testing approach that aims to parameterize force and moment tyre models compatible with the standard tyre interface. Full-vehicle tests are performed, and the results are compared to measurements from a mobile tyre testing rig on the same surface and to measurements on a flat belt machine. The results show that it is feasible to measure the inputs and outputs to the standard tyre interface on a flat road surface with the used experimental setup. The flat belt surface and the surface on the test track show similar characteristics. The maximum lateral force is sensitive to the chosen manoeuvres, likely due to temperature differences and to vibrations at large slip angles. For tyre models that do not model these effects, it is vital to test the tyres in a manoeuvre that creates comparable conditions for the tyres as the manoeuvre in which the tyre model will be used.
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3.
  • Albinsson, Anton, 1989, et al. (författare)
  • Validation of vehicle-based tyre testing methods
  • 2019
  • Ingår i: Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering. - : SAGE Publications. - 2041-2991 .- 0954-4070. ; 233:1, s. 18-27
  • Tidskriftsartikel (refereegranskat)abstract
    • The development process for passenger cars is both time- and resource-consuming. Full vehicle testing is an extensive part of the development process that consumes large amount of resources, especially within the field of vehicle dynamics and active safety. By replacing physical testing with complete vehicle simulations, both the development time and cost can potentially be reduced. This requires accurate simulation models that represent the real vehicle. One major chal- lenge with full vehicle simulation models is the representation of tyres in terms of force and moment generation. The force and moment generation of the tyres is affected by both operating conditions and road surface. Vehicle-based tyre testing offers a fast and efficient way to rescale force and moment tyre models to different road surfaces, in this study the Pacejka 2002 model. The resulting tyre model is sensitive to both the operating conditions during testing and the road surface used. This study investigates the influence of the slip angle sweep rate and road surface on the lateral tyre force characteristics of the fitted tyre model. Tyre models fitted to different manoeuvres are compared and the influence on the full vehicle behaviour is investigated in IPG Carmaker. The results show that by using the wrong road surface, the resulting tyre model can end up outside the tolerances specified by the ISO standard for vehicle simulation model verifi- cation in steady-state cornering. The use of Pacejka 2002 models parameterized in a steady-state manoeuvre to simulate the vehicle behaviour in sine-with-dwell manoeuvres is also discussed.
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4.
  • Anistratov, Pavel, et al. (författare)
  • Lane-deviation penalty formulation and analysis for autonomous vehicle avoidance maneuvers
  • 2021
  • Ingår i: Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering. - : SAGE Publications. - 0954-4070 .- 2041-2991. ; 235:12, s. 3036-3050
  • Tidskriftsartikel (refereegranskat)abstract
    • Autonomous vehicles hold promise for increased vehicle and traffic safety, and there are several developments in the field where one example is an avoidance maneuver. There it is dangerous for the vehicle to be in the opposing lane, but it is safe to drive in the original lane again after the obstacle. To capture this basic observation, a lane-deviation penalty (LDP) objective function is devised. Based on this objective function, a formulation is developed utilizing optimal all-wheel braking and steering at the limit of road–tire friction. This method is evaluated for a double lane-change scenario by computing the resulting behavior for several interesting cases, where parameters of the emergency situation such as the initial speed of the vehicle and the size and placement of the obstacle are varied, and it performs well. A comparison with maneuvers obtained by minimum-time and other lateral-penalty objective functions shows that the use of the considered penalty function decreases the time that the vehicle spends in the opposing lane.
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5.
  • Berglund, Kim, et al. (författare)
  • Prediction of driveline vibrations caused by ageing the limited slip coupling
  • 2016
  • Ingår i: Proceedings of the Institution of mechanical engineers. Part D, journal of automobile engineering. - : SAGE Publications. - 0954-4070 .- 2041-2991. ; 230:12, s. 1687-1698
  • Tidskriftsartikel (refereegranskat)abstract
    • The prediction of the wet-clutch service life still remains a challenge for scientists and engineers. Previous research has shown the significance of the wet-clutch friction characteristics on the driveline dynamics. To avoid driveline vibrations an increasing friction coefficient with increasing sliding speed is desirable. Consequently, prediction of the occurrence of driveline vibrations relies on a detailed knowledge of how the friction characteristics are affected by wet-clutch degradation, as well as an understanding of the driveline dynamics. Wet clutches are used in both automatic transmissions and all-wheel-drive systems in cars, where they are referred to as limited slip couplings by manufacturers. Wet clutches used in automatic transmissions are subjected to high slip levels, but for very limited time periods. In all-wheel-drive systems, where the limited slip coupling can be used to control the torque transfer to, for example, the rear wheels, the slip levels are low but continuous. Most wet-clutch research has been performed for clutches in automatic transmissions and not for clutches used in all-wheel-drive systems. Thus, a simulation model was developed to evaluate how different operating conditions of the limited slip coupling influence degradation of the friction characteristics and the tendencies towards driveline vibrations. First, the changes in the friction characteristics with the time of ageing are simulated. The friction characteristics after ageing are used as the input to a simplified driveline model, which is used to evaluate the occurrence of vibrations. It is shown how the developed simulation model can be used as an efficient tool for engineers. The developed simulation model can be used to predict how the operating conditions for the limited slip coupling influence degradation of the friction characteristics.
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6.
  • Boyraz Baykas, Pinar, 1981, et al. (författare)
  • Multi-sensor Driver Drowsiness Monitoring
  • 2008
  • Ingår i: Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering. - 2041-2991 .- 0954-4070. ; 222:11, s. 2041-2062
  • Tidskriftsartikel (refereegranskat)abstract
    • A system for driver drowsiness monitoring is proposed, using multi-sensor dataacquisition and investigating two decision-making algorithms, namely a fuzzy inference system(FIS) and an artificial neural network (ANN), to predict the drowsiness level of the driver.Drowsiness indicator signals are selected allowing non-intrusive measurements. The experi-mental set-up of a driver-drowsiness-monitoring system is designed on the basis of the sought-after indicator signals. These selected signals are the eye closure via pupil area measurement,gaze vector and head motion acquired by a monocular computer vision system, steering wheelangle, vehicle speed, and force applied to the steering wheel by the driver. It is believed that, byfusing these signals, driver drowsiness can be detected and drowsiness level can be predicted.For validation of this hypothesis, 30 subjects, in normal and sleep-deprived conditions, areinvolved in a standard highway simulation for 1.5 h, giving a data set of 30 pairs. For designing afeature space to be used in decision making, several metrics are derived using histograms andentropies of the signals. An FIS and an ANN are used for decision making on the drowsinesslevel. To construct the rule base of the FIS, two different methods are employed and comparedin terms of performance: first, linguistic rules from experimental studies in literature and,second, mathematically extracted rules by fuzzy subtractive clustering. The drowsiness levelsbelonging to each session are determined by the participants before and after the experiment,and videos of their faces are assessed to obtain the ground truth output for training thesystems. The FIS is able to predict correctly 98 per cent of determined drowsiness states(training set) and 89 per cent of previously unknown test set states, while the ANN has a correctclassification rate of 90 per cent for the test data. No significant difference is observed betweenthe FIS and the ANN; however, the FIS might be considered better since the rule base can beimproved on the basis of new observations.
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7.
  • Bruzelius, Fredrik, 1974-, et al. (författare)
  • Validation of a basic combined slip tyre model for use in friction estimation applications
  • 2014
  • Ingår i: Proceedings of the Institution of mechanical engineers. Part D, journal of automobile engineering. - : SAGE Publications. - 0954-4070 .- 2041-2991. ; 228:13, s. 1622-1629
  • Tidskriftsartikel (refereegranskat)abstract
    • Tyre modelling is an important part of understanding and estimating the tyre-road friction. In this paper a basic steady-state tyre model for the combined-slip case is derived. The model is intended to be used in friction estimations applications, where the model complexity is of high priority. The model, described using only two parameters, is validated with measured data from various conditions and tyre types using mobile measurement equipment. The performance from the measurements suggests that only two parameters are sufficient for the combined-slip case.
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8.
  • Fatima, Nowshir, et al. (författare)
  • Water contamination effect in wet clutch system
  • 2013
  • Ingår i: Proceedings of the Institution of mechanical engineers. Part D, journal of automobile engineering. - : SAGE Publications. - 0954-4070 .- 2041-2991. ; 227:3, s. 376-389
  • Tidskriftsartikel (refereegranskat)abstract
    • Water contamination in wet clutch systems can be a problem since both torque characteristics and wear resistance can be influenced by water presence. The present paper reveals the effect of externally added water on the wet clutch frictional performance. Commercially available standard paper based friction plates and steel separator plates lubricated in commercially available automatic transmission fluid were investigated in a recently developed automated test rig implementing a well confined experimental approach. Frictional response was observed for three different situations with different water amount and water exposure time. There is observed undesirable friction increase with increasing water amount in the system. The rate of increase in friction coefficient does not linearly depend on the amount of added water and this is a noticeable outcome from the common possible water contamination effects like change in lubricant viscosity, inadequate additive performance and weakening of friction material. The more reduced separator plates’ surface roughness (Ra) in a water contaminated clutch system compared to an uncontaminated one can be a reason for the change in friction. It is also shown that different water exposure time has no large impact on the change in friction level and separator plate’s roughness.
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9.
  • Franzke, Randi, 1989, et al. (författare)
  • Experimental investigation of the air flow in a simplified underhood environment
  • 2022
  • Ingår i: Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering. - : SAGE Publications. - 2041-2991 .- 0954-4070. ; 236:10-11, s. 2272 -2282
  • Tidskriftsartikel (refereegranskat)abstract
    • In this paper, a simplified underhood environment is proposed to investigate the air flow distribution in a vehicle-like set-up and provide high quality measurement data that can be used for the validation of Computational Fluid Dynamic methods. The rig can be equipped with two types of front openings representative for electrified vehicles. Furthermore, it is possible to install differently shaped blockages downstream of the fan to imitate large underhood components. The distance between the blockages and the fan can be varied in longitudinal and lateral direction. The measurements are performed with Laser Doppler Anemometry at a fixed distance downstream of the fan. The results show that the lack of an upper grille opening in the configuration for a battery electric vehicle has a notable impact on the flow field in the reference case without any downstream blockage. However, the differences in the flow field between the two front designs become less when a downstream obstruction is present. The longitudinal and lateral position of the blockages have have a minor impact on the flow field compared to the shape of the obstacle itself.
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10.
  • Genell, Anders, 1974, et al. (författare)
  • Multi-sensory congruence in vehicle sound quality assessment: effects of vibration and irrelevant emotional primes on affective reactions and evaluations of product sounds
  • 2010
  • Ingår i: Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering. - 2041-2991 .- 0954-4070. ; 224:D10, s. 1303-1310
  • Tidskriftsartikel (refereegranskat)abstract
    • A listening test was performed where a group of professional truck drivers were asked to rate their impressions of binaurally recorded interior truck sound of different levels, while subjected to different vibration levels in the steering wheel and in the foot rest of a truck simulator. The hypothesis was that, if the sound and vibrations had the same relative levels as the original environment inside a real truck cabin, the emotional reactions would not be as negative as if either of the modalities was significantly increased relative to the other. The results indicate some support for this hypothesis. In addition, the effects of irrelevant emotional primes on sound quality assessment were studied. The results are discussed in relation to multi-modal theories of emotional sound design for vehicle interiors.
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11.
  • Ghanaati, Ali, 1979, et al. (författare)
  • Design of a virtual test cell based on GMDH-type neural network for a heavy-duty diesel engine
  • 2021
  • Ingår i: Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering. - : SAGE Publications. - 2041-2991 .- 0954-4070. ; 235:2-3, s. 436-445
  • Tidskriftsartikel (refereegranskat)abstract
    • The engine development process faces big challenges from new strict emission regulations in addition to the need for fuel efficiency improvements. The Software-in-the-Loop (SiL) and Hardware-in-the-Loop (HiL) environments decreases the required time during engine development, calibration, verification, and validation of the product. An accurate and easy to build dyno-engine model with real-time operational ability is required for this purpose. Artificial Neural Networks (ANN) have shown ability to model dynamic and complex systems like internal combustion engines. In this paper, the Group Method of Data Handling (GMDH) algorithm was utilized to build an ANN model of a heavy-duty diesel engine. One objective is to reduce the amount of manual labor on the results during the ANN model development process. The GMDH algorithm is a self-organizing process that will find the system laws and optimize the model structure automatically in one iteration. The GMDH model results were compared with a model developed by Levenberg-Marquardt Backpropagation (LM-BP) algorithm. The ANN models used actuator signals from an Engine Management System (EMS) to simulate the engine operation parameters. As revealed by the simulation results, the ANN models successfully predicted engine torque, fuel flow, and NOx concentration. The GMDH model as a self-organized model reduced lead time, had slightly higher transient cycle accuracy, had fewer inconsistent predictions, and demonstrated better extrapolation capability. The prediction accuracy for transient operation was improved by shifting the predicted value by calculating time delay and a decrease of 76.66% for fuel flow and 66.51% for NOX concentration in model accuracy were achieved. The GMDH dyno-engine model can be effectively applied as a virtual test cell instrument for testing, calibration, and optimization purposes.
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12.
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13.
  • Henderson, Leon, 1986, et al. (författare)
  • Full-scale testing of a novel slip control braking system for heavy vehicles
  • 2016
  • Ingår i: Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering. - : SAGE Publications. - 2041-2991 .- 0954-4070.
  • Tidskriftsartikel (refereegranskat)abstract
    • This paper summarises the measured emergency braking performance of a tri-axle heavy goods vehicle semitrailer fitted with a novel pneumatic slip control braking system developed by the Cambridge Vehicle Dynamics Consortium. Straight-line braking tests were carried out from 40 km/h in order to compare a commercially electro-pneumatic available anti-lock braking system and the Cambridge Vehicle Dynamics Consortium system, which has bi-stable valves coupled with a sliding-mode slip controller. On average, the Cambridge Vehicle Dynamics Consortium system reduced the stopping distance and the air use by 15% and 22% respectively compared with those for the conventional anti-lock braking system. The most significant improvements were seen on a wet basalt-tile surface (with similar friction properties to ice) where the stopping distance and the air use were improved by 17% and 30% respectively. A third performance metric, namely the mean absolute slip error, is introduced to quantify the ability of each braking system to track a wheel slip demand. Using this metric, the bi-stable valve system is shown to improve the wheel slip demand tracking by 62% compared with that of the conventional anti-lock braking system. This improvement potentially allows more accurate control of the wheel forces during extreme manoeuvres, providing scope for the future development of advanced stability control systems.
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14.
  • Hobeika, Teddy, 1988, et al. (författare)
  • Experimental and numerical investigations of cooling drag
  • 2017
  • Ingår i: Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering. - : SAGE Publications. - 2041-2991 .- 0954-4070. ; 231:9 (SI), s. 1203-1210
  • Tidskriftsartikel (refereegranskat)abstract
    • As the target figures for CO2 emissions are reduced every year, vehicle manufacturers seek to exploit all possible gains in the different vehicle attributes. Aerodynamic drag is an important factor that affects the vehicle’s fuel consumption, and its importance rises with the shift from the New European Driving Cycle to the Worldwide harmonized Light vehicles Test Cycle which has a higher average speed. In order to reduce vehicle drag, car manufacturers employ the use of grill/spoiler shutters which reduces the amount of air going through the vehicle’s cooling system, also known as cooling flow, thus reducing both its cooling capability and the resultant cooling drag. This paper investigates the influence of different grill blockages on the cooling flow through the radiator of a Volvo S60. By modifying the engine bay and radiator, load cells are used to measure the force acting on the radiator core while the velocity distribution across the radiator core is measured using pressure probes. These values are analyzed and compared to different vehicle configurations and grill inlet designs. A number of test configurations are reproduced in Computational Fluid Dynamics simulations and compared to the test results. For some grill configurations, the simulations provide a good prediction of mass flow and velocity distribution; however a clear discrepancy is present as the grill blockages increase. On the other hand, the force acting on the radiator core was well predicted for all configurations. This paper discusses the different parameters affecting cooling flow predictions such as wind tunnel blockage and measurement grid discretization by comparing radiator forces and mass flows. In addition, the changes on overall vehicle forces are discussed with the radiator force put in context with cooling drag.
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15.
  • Holgerson, Mikael, et al. (författare)
  • Engagement behaviour of a paper-based wet clutch Part 1: Influence of drive torque
  • 1999
  • Ingår i: Proceedings of the Institution of mechanical engineers. Part D, journal of automobile engineering. - : SAGE Publications. - 0954-4070 .- 2041-2991. ; 213:4, s. 341-348
  • Tidskriftsartikel (refereegranskat)abstract
    • Owing to increasing demands when designing wet clutches for automatic transmissions, more knowledge about their behaviour is needed. In cars with power shifting automatic transmissions, an engine torque is continuously transmitted through the gear box. Most experimental and theoretical work concerning investigations of wet clutches today uses the inertia type of test apparatus, e.g. the SAE test machine 2. However, this type of test machine has no possibility of investigating the influence of a drive torque from the power supply. In order to investigate the influence of drive torque on wet clutch engagements, a new type of apparatus was built, which can operate with different combinations of inertia and drive torque. This apparatus can perform engagements more similar to those in automatic transmissions. The aim of this paper was to compare experimental outputs obtained using these principles of testing, concerning the influence of drive torque. It was found that the friction characteristics of wet clutches are independent of how the input energy is produced. This means that friction can be investigated with both principles. It was also found that an apparatus using only inertia gives shorter engagement times and higher temperatures than an apparatus including a drive torque at the same level of input energy. This can be explained by different power characteristics. Therefore, when investigating temperatures of wet clutch engagements, one must be careful when translating the results into reality.
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16.
  • Holgerson, Mikael, et al. (författare)
  • Engagement behaviour of a paper-based wet clutch Part 2: Influence of temperature
  • 1999
  • Ingår i: Proceedings of the Institution of mechanical engineers. Part D, journal of automobile engineering. - : SAGE Publications. - 0954-4070 .- 2041-2991. ; 213:5, s. 449-455
  • Tidskriftsartikel (refereegranskat)abstract
    • To increase comfort, performance and fuel economy, a more careful optimization of automatic transmissions is needed. Of special interest is how the temperature influences the engagement characteristics. In order to increase the level of knowledge in this area, a wet clutch test rig including a drive torque and inertia was used. The temperature and the developed energy were varied in order to investigate their influence on the characteristics of an engagement. As a consequence the influence of instant temperature, maximum temperature and instant normal force was also studied. Some of the most important conclusions of the investigation are that both the dynamic and static friction coefficients slightly decrease and the engagement time increases with increasing temperature. It was also found that the static and dynamic friction coefficients are not influenced by energy if the instant temperature is the same. An important parameter that describes the risk of stick-slip is the quotient between the static and dynamic friction. It was found that this quotient decreases with increasing temperature, and thus the risk of stick-slip is also supposed to decrease.
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17.
  • Hyttinen, Jukka, et al. (författare)
  • Constitutive rubber model suitable for rolling resistance simulations of truck tyres
  • 2022
  • Ingår i: Proceedings of the Institution of mechanical engineers. Part D, journal of automobile engineering. - : SAGE Publications. - 0954-4070 .- 2041-2991.
  • Tidskriftsartikel (refereegranskat)abstract
    • Tyres are a vital vehicle component forming an interface between a vehicle and the road, enabling the generation of braking, steering and traction forces. However, they also generate rolling resistance which researchers have tried to minimise through the years for environmental and economic reasons. Despite numerous attempts to model rolling resistance of tyres there still does not seem to exist a simple, flexible and accepted way of modelling rolling resistance in the time domain as well as parametrising models in an easy and accessible way. This study explores a simple and intuitive way of parametrising a hyperviscoplastic parallel rheological framework. In the experimental part of this study, rubber samples with various amounts of carbon black filler are extracted from a truck tyre section and tested using dynamic mechanical analysis. The test data was used to parametrise the material model. The model consists of Mooney-Rivlin hyperelasticity, 40 Prony elements and 8 perfectly plastic elements with Ogden hyperelasticity. The paper introduces a method to obtain a large number of parameters using only six tuneable parameters, which simplifies the tuning of the model drastically. The parametrised model is suitable for tyre rolling resistance simulations with frequency and strain amplitude dependency of the storage and loss modulus. A wide range of strain amplitudes and frequencies can be covered with the proposed method and it is possible to achieve a good fit for the storage and loss modulus values with the benefit of only a few tuneable parameters. Additional Prony or plastic networks do not increase the amount of tuneable parameters. Moreover, the method can be used to parametrise the material using manual iterations which is generally not possible for a parallel rheological framework with such a large amount of parameters. 
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18.
  • Häggström, Daniel, et al. (författare)
  • Optimization of synchronizer cone angle with regard to manufacturing tolerances of cone roundness and cone angle
  • 2020
  • Ingår i: Proceedings of the Institution of mechanical engineers. Part D, journal of automobile engineering. - : SAGE PUBLICATIONS LTD. - 0954-4070 .- 2041-2991. ; 234:2-3, s. 681-688
  • Tidskriftsartikel (refereegranskat)abstract
    • The effects of manufacturing tolerances on the maximum focal temperature has been investigated by transient thermomechanical simulations. Both relative cone angle and cone out-of-roundness for molybdenum and carbon fibre reinforced polymer synchronizers were evaluated. It was shown that cone out-of-roundness significantly increases the focal contact temperature for that specific cone but has little impact on the opposing cone. Two populations of measured synchronizers were evaluated, and it was shown that the maximum focal surface temperature can be decreased in almost all tolerance cases by introducing a relative angle between the cones.
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19.
  • Irfan, Muhammad, 1986, et al. (författare)
  • Minimizing synchronization time of a gear shifting mechanism by optimizing its structural design parameters
  • 2020
  • Ingår i: Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering. - : SAGE Publications. - 2041-2991 .- 0954-4070. ; 234:2-3, s. 488-504
  • Tidskriftsartikel (refereegranskat)abstract
    • A gear shifting mechanism is modeled in GT-Suite software. The mechanism has three main bodies: sleeve, ring, and gear. Results obtained from the simulation show that GT-Suite model can predict gear shifting process. Synchronization processes for three conditions of nominal, road grade, and vibrational motion of the master are studied in six cases by considering the sleeve and the gear as a master alternatively. The optimization based on the GT-Suite model is performed for each case to find the minimum gear shifting time based on variations of 17 structural design parameters. Minimum synchronization time is found almost same in all cases. It is concluded from closeness of the optimization results that average of the parameter values can be considered as optimized values for all cases. At the end, robustness of the optimized structural design parameters are analyzed with respect to the road grade, amplitude, and frequency of oscillatory excitation of rotational motion of the master.
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20.
  • Islam, Manjurul, 1984, et al. (författare)
  • A comparative study of multi-trailer articulated heavy-vehicle models
  • 2014
  • Ingår i: Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering. - : SAGE Publications. - 2041-2991 .- 0954-4070. ; , s. 1-29
  • Tidskriftsartikel (refereegranskat)abstract
    • This paper provides valuable guidelines on the selection of dynamic vehicle models for control algorithm development, design optimization and linear stability analysis for multi-trailer articulated heavy vehicles with active safety systems. The validation of yaw-plane and yaw–roll models of a tractor–two-semitrailer combination using the TruckSim software package is presented in this paper. A linear four-degree-of-freedom yaw-plane model and a linear seven-degree-of-freedom yaw–roll model of the vehicle were generated, compared and evaluated. The linear models of the multi-trailer articulated heavy vehicle yield numerical simulation results which are validated by comparing with those obtained from the corresponding non-linear TruckSim model. This paper also includes eigenvalue and frequency-response analysis of the linear models to estimate the unstable motion modes and to predict the unique dynamic features of the multi-trailer articulated heavy vehicle in the frequency domain. A benchmark investigation of the models was performed to examine the fidelity, the complexity and the applicability of the linear models.
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21.
  • Ivarsson, Maria, 1977-, et al. (författare)
  • Look-ahead control – consequences of a non-linear fuel map on truck fuel consumption
  • 2009
  • Ingår i: Proceedings of the Institution of mechanical engineers. Part D, journal of automobile engineering. - London : Professional Engineering Publishing. - 0954-4070 .- 2041-2991. ; 223:10, s. 1223-1238
  • Tidskriftsartikel (refereegranskat)abstract
    • Consequences of non-linearities in specific fuel consumption (SFC) of a heavy truck combustion engine are studied with focus on such small road gradients that a constant speed is optimal if the engine torque has an affine relation to fuelling. A quasi-static analysis gives valuable insights into the intrinsic properties of minimization of fuel consumption. Two objective functions are shown to give different optimal velocity trajectories on a constant road gradient, when the non-linearity in SFC is significant, a notation which is quantified. For a significant non-linearity, when a constraint is set to keep a final time, switching between twocharacteristic speeds is optimal. Alternatively, if consumed time, in addition to fuel consumption, is part of the objective function, then keeping to one constant speed is optimal also for significant non-linearities. However, the different optimal solutions still show similarities, since for a certain significant non-linearity a specific speed range determined by the characteristic velocities is shown to be unobtainable for both optimality criteria. Similarresults are obtained for a full dynamic model including a realistic fuel map and other realistic constraints.
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22.
  • Jacobson, Bengt J H, 1962 (författare)
  • Outline of a New Control Concept for Power Shifting of Fixed Step Ratio Automotive Transmissions
  • 2001
  • Ingår i: Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering. - 2041-2991 .- 0954-4070. ; 215:5, s. 613-624
  • Tidskriftsartikel (refereegranskat)abstract
    • Power shifting transmissions, e.g. automatic transmissions, are traditionally shifted from gear A to B by disengaging a clutch belonging to gear A and engaging a clutch belonging to gear B. This paper tries out the idea of employing a third clutch. In practice, such a third clutch can be one of the clutches which is traditionally used only for other gears. This means that the new concept can be used with only a control software update in an ordinary gearbox. The trade-off between comfort and wear, which is experienced in the traditional control concept, becomes less troublesome. The wear, or the discomfort, can be reduced to roughly half of that corresponding to a traditionally controlled upshift. The work finds the largest potential in using an extra clutch which belongs to a gear higher than the high gear in an upshift. The theoretical study is carried out with a general and simple model, but a simulation example is added using a more detailed model of an existing gearbox.
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23.
  • Jacobson, Bengt J H, 1962 (författare)
  • Potential of electric wheel motors as new chassis actuators for vehicle manoeuvring
  • 2002
  • Ingår i: Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering. - 2041-2991 .- 0954-4070. ; 2016:8, s. 631-640
  • Tidskriftsartikel (refereegranskat)abstract
    • The stability and yaw control systems in today's vehicles are increasingly appreciated for active safety. They use individual wheel braking to obtain an extra yaw moment. Adding individual traction, e.g. through electric wheel motors, would increase the available extra yaw moment. The present work investigates the manoeuvrability potential of such a concept. A passenger car employing electric wheel motors at the rear axle is compared with the same vehicle using only brake intervention. The potential, or ultimate limits, are investigated for two driving situations. The time delay in yaw speed change when entering a curve is estimated. A reduction of some 10-30 per cent is found, the highest gains being at low longitudinal speed. For pure lateral translation, the maximum initial lateral acceleration is estimated and a 40 per cent increase is predicted. The investigation is based on mathematical analysis employing a modified version of the common bicycle model. The feasibility of introducing these solutions in series-produced vehicles is discussed briefly. Cost aspects are not considered in any great detail, but it is emphasized that such aspects must be weighed not only against improved manoeuvrability but also against reduced environmental impact and improved longitudinal driveability, all of which are attainable with electric propulsion.
  •  
24.
  • Kharrazi, Sogol, 1980, et al. (författare)
  • A generic controller for improving lateral performance of heavy vehicle combinations
  • 2013
  • Ingår i: Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering. - : SAGE Publications. - 2041-2991 .- 0954-4070. ; 227:D5, s. 619-642
  • Tidskriftsartikel (refereegranskat)abstract
    • A generic controller for improving the lateral performance of heavy vehicle combinations by steering the axles of the towed units is proposed. The lateral performance of nine heavy vehicle combinations, including conventional combinations and existing and prospective longer combinations, are studied with and without the controller. The performance of the passive vehicles clearly indicates a need for improvements, which can be achieved by the proposed controller. The results obtained for controller verification in the frequency and time domains demonstrate that the controller reduces the yaw rate rearward amplification and off-tracking of all studied vehicles significantly, and diminishes trailer swings without reducing manoeuvrability. Furthermore, as a by-product, it moderately reduces the lateral acceleration rearward amplification. The improvements obtained by the proposed controller can promote the use of longer combination vehicles in traffic, which will result in a reduction of congestion, as well as substantial environmental and economic benefits.
  •  
25.
  • Klomp, Matthijs, 1976, et al. (författare)
  • On optimal recovery from terminal understeer
  • 2014
  • Ingår i: Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering. - : SAGE Publications. - 2041-2991 .- 0954-4070. ; 228:4, s. 412-425
  • Tidskriftsartikel (refereegranskat)abstract
    • This paper addresses the problem of terminal understeer and its mitigation via integrated brake control. The scenario considered is when a vehicle enters a curve at a speed that is too high for the tyre-road friction limits and an optimal combination of braking and cornering forces is required to slow the vehicle down and to negotiate the curve. Here, the driver commands a step steering input, from which a circular arc reference path is inferred. An optimal control problem is formulated with an objective to minimize the maximum off-tracking from the reference path, and two optimal control solutions are obtained. The first is an explicit analytical solution for a friction-limited particle; the second is a numerically derived open-loop brake control sequence for a nonlinear vehicle model. The particle solution is found to be a classical parabolic trajectory associated with a constant acceleration vector of the global mass center. The independent numerical optimization for the vehicle model is found to approximate closely the kinematics of the parabolic path reference strategy obtained for the particle. Using the parabolic path reference strategy, a closed-loop controller is formulated and verified against the solution from numerical optimization. The results are further compared with understeer mitigation by yaw control, and the parabolic path reference controller is found to give significant improvement over yaw control for this scenario.
  •  
26.
  • Körning-Ljungberg, Jessica, et al. (författare)
  • Psychological effects of combined noise and whole body vibration : a review and avenues for future research
  • 2010
  • Ingår i: Proceedings of the Institution of mechanical engineers. Part D, journal of automobile engineering. - 0954-4070 .- 2041-2991. ; 224:D10, s. 1289-1302
  • Tidskriftsartikel (refereegranskat)abstract
    • Vehicle drivers are often exposed to noise, whole-body vibrations (WBV) and mental loads, but the knowledge of how combined effects from multiple environmental stressors affect mental load is sparse. Studies have shown that the effect of one factor may be different than the effect of two factors presented together. For example, negative combined effects have been found when people perform mental tasks (e.g., Sommer and Harris, 1973; Harris and Schoenberger, 1980), as well as in subjective ratings (e.g., Ljungberg, Neely, Lundström, 2004). Although some of the studies investigating the combined effects of noise and WBV suffer from low ecological validity and few have investigated the possible effects on higher cognitive functions. Applying methods well-known to be sensitive to sound exposures by using serial recall tasks (e.g., Jones, Madden & Miles, 1992) as well as methods developed in the studies of noise after-effects (e.g., Glass & Singer, 1972) may be a way to continue the research field of combined effects of noise and WBV
  •  
27.
  • le Gigan, Gael, 1985, et al. (författare)
  • Disc brakes for heavy vehicles: An experimental study of temperatures and cracks
  • 2015
  • Ingår i: Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering. - : SAGE Publications. - 2041-2991 .- 0954-4070. ; 229:6, s. 684-707
  • Tidskriftsartikel (refereegranskat)abstract
    • A better understanding of the thermomechanical loading of brake discs is important for controlling material fatigue and crack propagation in the disc. In the present study, full-scale drag braking experiments were performed on brake discs made from eight different grey cast iron alloys. The well-performing materials were also tested with an alternative brake pad material. A testing procedure with repeated drag brakings was used. The disc and pad temperatures were registered by thermocouples embedded at selected locations, and the disc surface temperatures by a thermocamera. Extensive analyses of the measured temperatures were performed. The results for the thermocouples at the mid-radius of the disc and at the end of brake applications indicatd that the two sides of the disc have opposite deviations from the mean temperature. The temperature deviations are generally temporally alternating, but also stationary variations can be found. The thermocamera gives the possibility of identifying the phenomena behind the temperature variations found from the thermocouples. Banding of the disc–pads contact with alternating one band and two bands of high temperatures is observed for the studied brake discs exposed to severe braking load cases. Moreover, it was found that hot-spot patterns develop on the disc surface, which are spatially fixed during each brake application. However, they may be either slowly migrating or fixed relative to the disc during consecutive brake applications. Thermal images show that small cracks do not affect hot-spot migration as a hot spot migrates over the crack. However, at a critical length of the crack, the heat becomes localized at the crack and increases its growth, thus limiting the life of the disc. The tests indicate that a combination of hot-spot migration, alternating bands and small temperature differences over the disc are significant factors to be considered when improving the lifespan of the discs.
  •  
28.
  • le Gigan, Gael, 1985 (författare)
  • Improvement in the brake disc design for heavy vehicles by parametric evaluation
  • 2017
  • Ingår i: Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering. - : SAGE Publications. - 2041-2991 .- 0954-4070. ; 231:14, s. 1989-2004
  • Tidskriftsartikel (refereegranskat)abstract
    • Design of the brake disc geometry for a given brake disc material provides an opportunity for improvement in the fatigue life of the brake disc. High thermomechanical loads at braking lead to substantial local plastification and also induce tensile residual stresses in certain areas of the brake disc. This contributes to shortening of the fatigue life of the brake disc by possible initiation and growth of cracks. In the present paper, a simulation approach for evaluation of brake disc designs with respect to thermomechanical performance is developed and applied. Brake disc performance is analysed using commercial finite element software by employing a constitutive model for grey cast iron implemented in a Fortran subroutine. The thermal loading consists of consecutive severe braking cycles at a constant brake power and a constant speed, with cooling between the brake cycles. Based on a previous experimental study, three different assumptions are made regarding the spatial distribution of the thermal load at braking. A standard commercial brake disc made from grey cast iron having straight vanes is used as the reference case. Geometrical modifications are introduced in the ventilation arrangement using a design-of-experiments approach, studying both straight cooling vanes and different pillar layouts. A preliminary assessment of the fatigue life of the brake discs is carried out. The results indicate that the introduction of different pillar arrangements instead of straight vanes make it possible to decrease the mass of the brake disc by up to 13% or to increase the fatigue life of the brake disc by about 50%.
  •  
29.
  • le Gigan, Gael, 1985, et al. (författare)
  • Modelling of grey cast iron for application to brake discs for heavy vehicles
  • 2017
  • Ingår i: Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering. - : SAGE Publications. - 2041-2991 .- 0954-4070. ; 231:1, s. 35-49
  • Tidskriftsartikel (refereegranskat)abstract
    • Cast iron brake discs are commonly used in the automotive industry, and efforts are being made to gain a better understanding of the thermal and mechanical phenomena occurring at braking. The high thermomechanical loading at braking arises from interaction between the brake disc and the brake pads. Frictional heating generates elevated temperatures with a non-uniform spatial distribution often in the form of banding or hot spotting. These phenomena contribute to material fatigue and wear and possibly also to cracking. The use of advanced calibrated material models is one important step towards a reliable analysis of the mechanical behaviour and the life of brake discs. In the present study, a material model of the Gurson-Tvergaard-Needleman type is adopted, which accounts for asymmetric yielding in tension and compression, kinematic hardening effects, viscoplastic response and temperature dependence. The material model is calibrated using specimens tested in uniaxial cyclic loading for six different temperatures ranging from room temperature to 650 °C. A special testing protocol is followed which is intended to activate the different features of the material model. Validation of the model is performed by using tensile tests and thermomechanical experiments. An application example is given where a 10° sector of a brake disc is analysed using the commercial finitie element code Abaqus under a uniformly applied heat flux on the two friction surfaces. The results indicate that the friction surface of the hat side and the neck can be critical areas with respect to fatigue for the uniform heating studied.
  •  
30.
  • le Gigan, Gael, 1985, et al. (författare)
  • Thermomechanical fatigue of grey cast iron brake discs for heavy vehicles
  • 2019
  • Ingår i: Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering. - : SAGE Publications. - 2041-2991 .- 0954-4070. ; 233:2, s. 453-467
  • Forskningsöversikt (refereegranskat)abstract
    • The development of fatigue life assessment models for vehicle components exposed to thermomechanical fatigue supports the establishing of adequate maintenance intervals that neither cause unnecessary vehicle downtime, nor jeopardize the function of the components. In modern automotive applications, braking is closely related to safety and is commonly performed with disc brakes. Failure here may result in structural damage or even breakdown and loss of lives. In the present work, the cyclic response of grey cast iron is analysed and the fatigue life of brake discs made from this material is studied by use of four different fatigue life assessment models: the Smith–Watson–Topper model, the Coffin–Manson model and two mechanism-based damage models. Results from isothermal and thermomechanical experiments on uniaxially loaded specimens are used for calibration of the models. Finally, the models are used to assess the life of a brake disc for a simulated brake dynamometer experiment. It is found that the fatigue model parameters that are calibrated using different sets of isothermal uniaxial test data show a substantial spread. A comparison with results from full-scale brake rig experiments shows that predictions by any of the models that have been calibrated using data from a well-designed thermomechanical test are in reasonable agreement with the estimated crack initiation phase for actual brake disc lives. It can be concluded that it is not sufficient to calibrate the studied fatigue life models using isothermal uniaxial tests for predictions of thermomechanical fatigue lives.
  •  
31.
  • Li, Xiaojian, 1991, et al. (författare)
  • A new method for performance map prediction of automotive turbocharger compressors with both vaneless and vaned diffusers
  • 2021
  • Ingår i: Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering. - : SAGE Publications. - 2041-2991 .- 0954-4070. ; 235:6, s. 1734-1747
  • Tidskriftsartikel (refereegranskat)abstract
    • A new approach to predict the performance maps of automotive turbocharger compressors is presented. Firstly, a polynomial equation is applied to fit the experimental data of flow coefficient ratios for the centrifugal compressors with both vaneless and vaned diffusers. Based on this equation, the choke and surge flow coefficients under different machine Mach numbers can be quickly predicted. Secondly, a physically based piecewise elliptic equation is used to define compressors’ characteristic curves in terms of efficiency ratio. By introducing the flow coefficient ratio into the efficiency correlation, the empirical coefficients in the piecewise elliptic equation are uniquely calibrated by the experimental data, forming a unified algebraic equation to match the efficiency maps of the compressors with both vaneless and vaned diffusers. Then, a new universal equation, which connects the work coefficient, the impeller outlet flow coefficient and the non-dimensional equivalent impeller outlet width, is derived by using classical aerothermodynamic method. The off-design pressure ratio is predicted based on the equivalent impeller outlet width with less knowledge of the compressor geometry and no empirical coefficients. Finally, three state-of-the-art turbocharger compressors (one with vaneless diffuser, two with vaned diffusers) are chosen to validate the proposed method, and the results show a satisfactory accuracy for the performance map prediction. This method can be used for the preliminary design of turbocharger compressors with both vaneless and vaned diffusers, or to assess the design feasibility and challenges of the given design specifications.
  •  
32.
  • Lindström, Mikael, et al. (författare)
  • A study of combustion and emission formation characteristics during production engine transients using optical diagnostics
  • 2011
  • Ingår i: Proceedings of the Institution of mechanical engineers. Part D, journal of automobile engineering. - : SAGE Publications. - 0954-4070 .- 2041-2991. ; 225:D9, s. 1290-1303
  • Tidskriftsartikel (refereegranskat)abstract
    • In order to identify some of the special combustion and emission formation phenomena that occur in a turbocharged heavy-duty diesel engine during transient operation, the transient strategy of a production engine has been characterized at four different engine speeds. From each transient some points have been selected for further investigation by recreating these load points as steady-state points in a single-cylinder engine. This allows the emissions to be measured with a high degree of accuracy. An endoscope which makes it possible to evaluate flame temperatures was used in both engines. An empirically derived method of calculating nitric oxide (NO) formation from a combination of measured flame temperature, calculated gas temperature, and heat release rate has been developed and applied. This provides an increased understanding of combustion and emission formation phenomena during transient operation. An optical engine was also used to provide a full combustion chamber view for some of the operating points, and a specially developed software was used to calculate temperature distributions based on high-speed camera colour information. The NO formation formula was applied on these images, which resulted in spatially resolved NO formation distributions.
  •  
33.
  • Lundström, Andreas, 1980, et al. (författare)
  • Modelling of urea gas phase thermolysis and theoretical details on urea evaporation
  • 2011
  • Ingår i: Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering. - : SAGE Publications. - 2041-2991 .- 0954-4070. ; 225:10, s. 1392-1398
  • Tidskriftsartikel (refereegranskat)abstract
    • A model study of droplet decomposition of a urea–water solution (UWS) for selective catalytic reduction applications (SCR) has been undertaken. A new vapour pressure equation for urea has been adopted to predict the rate of urea evaporation. The vapour pressure above liquid urea is obtained by extrapolating the vapour pressure above solid urea. Gas phase decomposition of urea into ammonia and isocyanic acid is further assumed to be fast, dictating the boundary conditions for the evaporation process. The rate of UWS evaporation is compared to recently published data and shows good agreement. A set of Antoine parameters was fitted to the derived vapour pressure to facilitate future simulations.
  •  
34.
  • Meng, Zhiwei, 1996, et al. (författare)
  • GIVA: Interaction-aware trajectory prediction based on GRU-Improved VGG-Attention Mechanism model for autonomous vehicles
  • 2023
  • Ingår i: Proceedings of the Institution of Mechanical Engineers. Part D, Transport engineering. - 2041-2991 .- 0954-4070. ; In Press
  • Tidskriftsartikel (refereegranskat)abstract
    • Predicting future trajectories is crucial for autonomous vehicles, as accurate predictions enhance safety and inform subsequent decision-making and planning modules. This is however a challenging task due to the complex interactions between surrounding vehicles. Existing methods struggled to extract deep representations and often overlook spatial dependence. To address this problem, this paper introduces GIVA, an interaction-aware trajectory prediction method based on the Gated Recurrent Unit (GRU)-Improved Visual Geometry Group (VGG)-Attention Mechanism model. GIVA first encodes the historical trajectories of the target vehicle and its surrounding vehicles using a GRU Encoder. Next, an Interaction Module, which combines the Improved VGG Pooling Module and the Attention Mechanism Pooling Module, effectively captures spatial interaction features between vehicles. The Improved VGG Pooling Module extracts more detailed and effective interaction information, while the Attention Mechanism Pooling Module emphasizes the importance of surrounding vehicles for the target vehicle’s future trajectory. Lastly, the dynamic encoding feature of the target vehicle and the fused interaction feature are concatenated and input into a GRU Decoder to generate the future trajectory. Experiments on the public Next Generation Simulation (NGSIM) dataset showcase the effectiveness of GIVA compared to existing prediction approaches, demonstrating its potential for improving autonomous vehicle performance.
  •  
35.
  • Miller, Jonathan, et al. (författare)
  • Designing and testing an advanced pneumatic braking system for heavy vehicles
  • 2013
  • Ingår i: Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering. - 2041-2991 .- 0954-4070. ; 227:8, s. 1715-1729
  • Tidskriftsartikel (refereegranskat)abstract
    • Heavy goods vehicles exhibit poor braking performance in emergency situations when compared to other vehicles. Part of the problem is caused by sluggish pneumatic brake actuators, which limit the control bandwidth of their antilock braking systems. In addition, heuristic control algorithms are used that do not achieve the maximum braking force throughout the stop. In this article, a novel braking system is introduced for pneumatically braked heavy goods vehicles. The conventional brake actuators are improved by placing high-bandwidth, binary-actuated valves directly on the brake chambers. A made-for-purpose valve is described. It achieves a switching delay of 3–4 ms in tests, which is an order of magnitude faster than solenoids in conventional anti-lock braking systems. The heuristic braking control algorithms are replaced with a wheel slip regulator based on sliding mode control. The combined actuator and slip controller are shown to reduce stopping distances on smooth and rough, high friction (μ = 0.9) surfaces by 10% and 27% respectively in hardware-in-the-loop tests compared with conventional ABS. On smooth and rough, low friction (μ = 0.2) surfaces, stopping distances are reduced by 23% and 25%, respectively. Moreover, the overall air reservoir size required on a heavy goods vehicle is governed by its air usage during an anti-lock braking stop on a low friction, smooth surface. The 37% reduction in air usage observed in hardware-in-the-loop tests on this surface therefore represents the potential reduction in reservoir size that could be achieved by the new system.
  •  
36.
  • Minovski, Blago, 1986, et al. (författare)
  • A numerical investigation of thermal engine encapsulation concept for a passenger vehicle and its effect on fuel consumption
  • 2019
  • Ingår i: Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering. - : SAGE Publications. - 2041-2991 .- 0954-4070. ; 233:3, s. 557-571
  • Tidskriftsartikel (refereegranskat)abstract
    • Increasingly tough regulations for emission levels and a growing demand for an environmentally clean motor industry impose high requirements in modern automotive development. During recent decades, carmakers have been utilizing various strategies to minimize energy losses in the powertrain to meet legislative and market demands. A great part of research efforts has been focused on improving engine performance during cold starts characterized by increased friction losses. Thermal engine encapsulation is an effective design choice to reduce engine friction in applications with frequent cold starts. In the present work, a coupled 1-D–3-D system-level approach is used to investigate the effects of a novel engine-mounted encapsulation concept featuring air shutters on fuel consumption in a Volvo S80 passenger vehicle. Simulations are performed for sequences of the Worldwide harmonized light vehicles test cycle (WLTC) drive cycle, which include different time intervals of engine inactivity when the car is parked in air of an quiescent ambient temperature. The results show that engine encapsulation with high area coverage (97%) can retain engine oil temperature above 19°C for up to 16 h after engine shutdown at an ambient temperature of 5°C, leading to 2.5% fuel saving during engine warm-up when cold starts occur between 2 and 8 h after key-off. Encapsulations with a lower area coverage (90%) have proven to be less effective, with fuel saving of 1.25% as the temperatures of the oil and engine structures decrease more quickly after key-off compared to the fully enclosed encapsulation.
  •  
37.
  • Mårtensson, Per, et al. (författare)
  • Method for cost and weight-efficient material diversity and partitioning of a carbon fibre composite body structure
  • 2015
  • Ingår i: Proceedings of the Institution of mechanical engineers. Part D, journal of automobile engineering. - : Sage Publications. - 0954-4070 .- 2041-2991.
  • Tidskriftsartikel (refereegranskat)abstract
    • A method for the early concept phase is proposed, which is aimed at limiting the financial and performance-related riskswhen designing a carbon fibre composite automotive body structure. The method manages the structural requirementsimposed on the complete body structure and analyses the suitability of different carbon fibre material systems and pro-cesses. It also studies whether a high level of material diversity is desirable and the way in which to identify the optimalpartition of the body structure from a material system and manufacturing process selection point of view. Furthermore,since composite materials include both laminated materials and quasi-isotropic materials, an approach is presented thatenables the comparison of these materials variants during conceptual material selection. A case study exemplifies themethod and the results show that, in spite of the cost-sensitive nature of the automotive industry, utilization of the max-imum performance of these expensive composite materials is more important than efforts to achieve a rapid manufac-turing process.
  •  
38.
  • Nilsson, Ylva, et al. (författare)
  • Weak knock characterization and detection for knock control
  • 2009
  • Ingår i: Proceedings of the Institution of mechanical engineers. Part D, journal of automobile engineering. - 0954-4070 .- 2041-2991. ; 223:D1, s. 107-129
  • Tidskriftsartikel (refereegranskat)abstract
    • Knock is a fundamental phenomenon in combustion engines, and knock control is central in any engine management system. Better understanding of knock, and weak knock in particular, is considered from two main aspects: knock detection and knock characterization. The aim of knock detectors is both to detect knock and to estimate the crank angle at knock onset. Focusing on weaker knock than before, it is shown that knock detectors and algorithms have to take into account other characteristics of knock traces than the standard model. It is shown that the best-performing knock detector of those investigated is one that supervises changes in signal variance, except for low signal-to-noise ratios where it is advantageous to use also the oscillation frequency. Regarding characterization, an important result is that in a wide range of intensities there is an almost linear dependence between the logarithmic normalized knock energy and the rate of cycles with knock. This means for example that a knock controller can use feedback on the rate of cycles with knock instead of knock intensity and vice versa; both can in combination with better detection provide possibilities for smoother and more anticipatory control schemes.
  •  
39.
  • Papaioannou, Georgios, et al. (författare)
  • Optimal design of passenger vehicle seats with the use of negative stiffness elements
  • 2021
  • Ingår i: Proceedings of the Institution of mechanical engineers. Part D, journal of automobile engineering. - : Sage Publications. - 0954-4070 .- 2041-2991. ; 234:2-3, s. 610-629
  • Tidskriftsartikel (refereegranskat)abstract
    • A seat that provides good vibration isolation is of prime importance for passenger's safety and health. The main conflict in seat suspensions implies that the increasing initial deformation of the system (increase in "static discomfort") leads to better isolation of accelerations (increase in "dynamic comfort"). Many researchers have focused on overcoming or at least suppressing this conflict between load support capacity and vibration isolation by modeling new suspension systems, such as the so-called negative suspension systems. However, apart from the modeling of new suspension systems, optimization is an important part in designing a seat and finding the best compromise between these two objectives. Thus, in this work, four types of seat suspension systems with embedded negative stiffness elements are implemented and optimized in order to be benchmarked. Three of them have already been tested either in passenger or in an off-road vehicle seat. All the vibration isolators are optimized with genetic algorithms in respect to static and dynamic factors of ride comfort by applying constraints oriented to the objectives and the design of the structure. The optimization is implemented for two excitations, which correspond to a vehicle driving over road profiles of Classes A and B, and the common solutions are outlined.
  •  
40.
  • Papaioannou, Georgios, et al. (författare)
  • Skyhook control strategy for vehicle suspensions based on the distribution of the operational conditions
  • 2021
  • Ingår i: Proceedings of the Institution of Mechanical Engineers, Part P. - : SAGE Publications. - 1754-3371 .- 0954-4070 .- 2041-2991.
  • Tidskriftsartikel (refereegranskat)abstract
    • In this work, a novel distribution-based control strategy of semi-active vehicle suspensions is tested under different conditions. The novelty lies in the use of an appropriate threshold in the operational condition of the control algorithm, with which the operational conditions severity is quantified and the state of the damper is controlled according to the magnitude of the operational conditions and not their sign. The value of the threshold depends on the vibrations induced to the sprung mass by the road profile. In order to be evaluated, the operational conditions of the algorithm are fitted to a t-student distribution. The cumulative distribution function of this distribution is used in order to decrease the fraction of the sample operating with the damper’s stiff state. The strategy is applied to traditional SH control algorithms and is tested using a quarter car model excited by different road excitations. A sensitivity analysis for various threshold values is performed, investigating the impact of adopting the cumulative distribution functioned (CDF) controller to various performance metrics. The results illustrate an increase of up to 13% in the ride comfort of the passengers and increase of 6% in the road holding of the vehicle. Both are achieved by minimizing the switches of the damping ratio up to 80%
  •  
41.
  • Perricone, Guido, et al. (författare)
  • A proposed driving cycle for brake emissions investigation for test stand
  • 2020
  • Ingår i: Proceedings of the Institution of mechanical engineers. Part D, journal of automobile engineering. - : Sage Publications. - 0954-4070 .- 2041-2991. ; 234:1, s. 122-135
  • Tidskriftsartikel (refereegranskat)abstract
    • Particulate matter emission factors from vehicle brakes are difficult to assess directly from the field. Moreover, there is a lack of a standardized cycle and test stand for evaluating brake emissions. For these reasons, a test cycle was developed from real driving data collected from a car. This new test cycle was implemented on an inertia disc brake dynamometer appositely designed for brake particle emission studies. Results reveal that, for the brake system used as an example, the obtained emission factors for the urban driving conditions studied are comparable to EURO 6 regulations in terms of particle number and comparable to EURO 4 levels in terms of mass with brake emission factors equal to 4.37-6.46 x 10(11) particles/km and 44-48 mg/km, respectively.
  •  
42.
  • Perricone, Guido, 1973-, et al. (författare)
  • Towards a test stand for standardized measurements of the brake emissions
  • 2016
  • Ingår i: Proceedings of the Institution of mechanical engineers. Part D, journal of automobile engineering. - : Sage Publications. - 0954-4070 .- 2041-2991. ; 230:11, s. 1521-1528
  • Tidskriftsartikel (refereegranskat)abstract
    • Brake-related particulate matter contributes considerably to the non-exhaust emissions of the transport sector in urban areas of the world. The airborne particle emissions from automotive brakes currently lack any proper regulations. Future regulations require test stands, test cycles and particle instruments to be suitable for measuring the brake emissions. This present work focuses on the design of a novel test stand for reliable measurements of the brake emissions with a high sampling efficiency. A test stand in the form of an inertial disc brake dynamometer was redesigned to allow control of the cleanness of the incoming air and to assure isokinetic sampling. The cleanness of the incoming air, together with an over-pressurized chamber around the brake assembly, ensures that all the particles measured originate from the brake materials. In order to evaluate the novel design, the number and size distributions of the brake emissions are measured online with and without control of the cleanness of the intake air. The results reveal that this test stand can be proposed as a standard test stand to assess objectively the emissions of airborne brake particles in future regulations.
  •  
43.
  • Perricone, Guido, et al. (författare)
  • Towards the ranking of airborne particle emissions from car brakes - a system approach
  • 2017
  • Ingår i: Proceedings of the Institution of mechanical engineers. Part D, journal of automobile engineering. - : Sage Publications. - 0954-4070 .- 2041-2991. ; 231:6, s. 781-797
  • Tidskriftsartikel (refereegranskat)abstract
    • Airborne particulate matter emitted from motor vehicle brakes is a contributor to urban air quality. Therefore, a method to rank brake pairs (pads and rotors) with respect to their particle emission factors in a reliable way is needed to develop a low-emission disc brake. A novel inertial disc brake dynamometer designed for brake particle emission studies, a modified SAE J 2707 cycle, an electrical low-pressure cascade impactor and a filter are used to test five different pad materials against cast-iron rotors. By changing only the pad materials, it is shown that the differences between the mass emission factor and the number emission factor of the the worst brake pair and those of the best brake pair decreases by more than four times and 19 times respectively. Furthermore, the results show that the material combination ranked the best in terms of the mass emission factor is ranked the worst in terms of the number emission factor. The results reveal that this combination of a test stand, a test cycle and particle instruments can discriminate between different brake pair materials in a reliable way in the case of the mass emission factors while more research has to be carried out in the case of the number emission factors.
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44.
  •  
45.
  • Pohl, Jochen, 1971-, et al. (författare)
  • A semi-automated parallel parking system for passenger cars
  • 2006
  • Ingår i: Proceedings of the Institution of mechanical engineers. Part D, journal of automobile engineering. - 0954-4070 .- 2041-2991. ; 220:1, s. 53-65
  • Tidskriftsartikel (refereegranskat)abstract
    • Car parking has been, and still is, a growing problem, with increasing vehicle sizes in the luxury segment as well as sport-utility vehicles. This is especially true when bearing in mind the confined parking spaces in parking lots and cities. While damage during parking generally does not cause any injury to the passengers, it is costly and annoying. Park assist systems are by no means new on the market, since passive systems which provide longitudinal guidance using ultrasonic distance sensors have been available on the market for a number of years.The system presented is a semi-automated approach to parallel parking problems, as they frequently occur in European and Asian cities. The challenge during the development of this system was to have as few components as possible added to a standard vehicle, seeking reuse of many of the already built-in functionalities. The result is a system that leaves the longitudinal control of the vehicle to the driver but automates the steering process, and even stops the vehicle when the final parking position is reached.
  •  
46.
  • Romano, Luigi, 1994, et al. (författare)
  • Synthesis and comparative analysis of three model-based observers for normal load and friction estimation in intelligent tyre concepts
  • 2021
  • Ingår i: Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering. - : SAGE Publications. - 2041-2991 .- 0954-4070. ; 235:6, s. 1629-1642
  • Tidskriftsartikel (refereegranskat)abstract
    • Recently, the growing trends towards autonomous driving and full automation of terrestrial vehicles have intensified the need for intelligent and interconnected systems to collect and communicate reliable data in real-time. Since the tyres represent the primary sensing system between the vehicle and the ground, it comes natural to designate them to acquire information about their interaction with the road. Intelligent or smart tyre technologies can, indeed, be used to estimate both vehicle’s performance and environmental conditions, leading to handling, NVH and comfort improvements. Inspired by some encouraging results found in previous works, in this investigation we present three model-based estimators to detect the forces acting in the contact patch for an intelligent tyre. The underlying mathematical foundation is the Flexible Ring Tyre Model (FRM), which is able to describe the in-plane dynamics of intelligent tyre systems. More specifically, it represents the tyre treadband by means of a flexible ring restrained at its mean radius by a viscoelastic foundation. Due to its relatively simplicity, the FRTM allows to obtain a closed-form solution for the treadband displacements, accelerations and circumferential strain, whilst being accurate enough to capture all the relevant phenomena concerning the tyre dynamics. The governing Partial Differential Equations (PDEs) of the system are reduced to a set of coupled Ordinary Differential Equations (ODEs) by performing the Fourier series expansion. An optimal observer is then designed based on the Unscented Kalman Filter to account for the nonlinearities which arise when the vertical load acting on the tyre and the friction coefficient are included in the augmented state space representation. The three different technologies considered in this study are: strain, displacement, and acceleration-based intelligent tyres. All of them are shown to be capable of estimating the quantities of interest – the actual state of the system, the normal force and the adhesion coefficient – with high accuracy in very short times. Furthermore, the robustness of the proposed approach is validated by considering a step variation in both the vertical load and the available friction. The performances of the observers are finally compared by using the RSS and MSE indices.
  •  
47.
  • Sadeghi Kati, Maliheh, 1979, et al. (författare)
  • Gain-scheduled H Controller Synthesis for Actively-steered Longer and Heavier Commercial Vehicles
  • 2020
  • Ingår i: Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering. - : SAGE Publications. - 2041-2991 .- 0954-4070. ; 234:7, s. 2045-2065
  • Tidskriftsartikel (refereegranskat)abstract
    • This paper proposes a gain-scheduled controller synthesis for improving the lateral performance and stability of articulated heavy vehicles by active steering of the selected towed vehicle units. The longitudinal velocity is on-line measurable, and it is thus treated as a scheduling parameter in the gain-scheduled controller synthesis. The lateral performance of four articulated heavy vehicles, including existing Nordic heavy vehicles and prospective longer articulated heavy vehicles, are investigated with and without active steering and compared with a commonly used conventional tractor–semitrailer. The control problem is formulated as an ℋ∞H∞ static output feedback, which uses only information from articulation angles between the steered vehicle unit and the vehicle unit in front of it. The solution of the problem is obtained within the linear matrix inequality framework, while guaranteeing ℋ∞H∞ performance objectives. Effectiveness of the designed controller is verified through numerical simulations performed on high-fidelity vehicle models. The results confirm a significant reduction in yaw rate rearward amplification, lateral acceleration rearward amplification, and high-speed transient off-tracking, thereby improving the lateral stability and performance of all studied heavy vehicles at high speeds.
  •  
48.
  • Sebben, Simone, 1961, et al. (författare)
  • Characterization of the rear wake of a SUV with extensions and without extensions
  • 2017
  • Ingår i: Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering. - : SAGE Publications. - 2041-2991 .- 0954-4070. ; 231:9 (SI), s. 1294-1302
  • Tidskriftsartikel (refereegranskat)abstract
    • Passenger vehicles are considered to be bluff bodies, and therefore their total aerodynamic resistance is dominated by the pressure drag, which is basically the difference between the stagnation pressure at the front and the pressure at the base. In particular, the base wake of a vehicle has a significant influence on the total drag, and the ways to reduce and to control the drag have been the subject of numerous investigations. The present work focuses on the identification and analysis of unsteady-flow structures acting on the base wake of a sport utility vehicle with rear-end extensions and without rear-end extensions. Tapered extensions have proved to be an effective way to reduce the drag since they act as a truncated boat-tailing device which improves the pressure recovery zone and reduces the wake size. In this investigation, wind tunnel experiments and computational fluid dynamics were used to study the forces acting on the vehicle and the non-stationary behaviour of the rear wake flow. For analysis of the unsteady base pressures, a data-structure-sensitive filtering approach based on empirical mode decomposition in combination with fast Fourier transform and proper orthogonal decomposition was used. The numerical results and the experimental results complement each other well, and both revealed an antisymmetric mode in the transverse plane related to a flapping of the wake at a Strouhal number of around 0.23. Furthermore, a pumping effect, which is a main contributor to the drag, was observed at Strouhal values of between 0.04 and 0.07. This is in good agreement with the results from the research on more simplified model shapes. The rear extensions proved to be a productive way to reduce the drag coefficient and the magnitude of the wake flapping for the yaw angles investigated.
  •  
49.
  • Sharifzadeh, Seyed Mojtaba, 1988, et al. (författare)
  • An effective tyre to road friction estimation applied to heavy vehicles
  • 2024
  • Ingår i: Proceedings of the Institution of mechanical engineers. Part D, journal of automobile engineering. - : SAGE PUBLICATIONS LTD. - 0954-4070 .- 2041-2991.
  • Tidskriftsartikel (refereegranskat)abstract
    • Knowledge about the tyre to road friction is central to many vehicle functions as well as the overall performance of the vehicle. In this paper, a new real-time algorithm is presented for estimating the coefficient of friction using available on-board sensor information. A computationally efficient algorithm is presented, that reduces resources usage compared to previously published approaches. Issues connected to heavy vehicles and friction estimation is addressed, such as wind up of hub assembly and vehicle speed sensing. The performance of the algorithm is illustrated on data sets acquired from the test track recordings in winter conditions.
  •  
50.
  • Sivertsson, Martin, et al. (författare)
  • Optimal stationary control of diesel engines using periodic control
  • 2017
  • Ingår i: Proceedings of the Institution of mechanical engineers. Part D, journal of automobile engineering. - : Sage Publications. - 0954-4070 .- 2041-2991. ; 231:4, s. 457-475
  • Tidskriftsartikel (refereegranskat)abstract
    • Measurements and optimal control are used to study whether the fuel economy of a diesel engine can be improved through periodic control of the wastegate, illustrating how modern optimal control tools can be used to identify non-trivial solutions that can improve performance. The measurements show that the pumping torque of the engine is changed when the wastegate is controlled in a periodic manner versus stationary even if the mean position is the same. If this decreases the fuel consumption or not is seen to be frequency and operating point dependent. The measurements indicate that the phenomenon occurs in the time scales capturable by mean value engine models (MVEM). The operating points are further analyzed using a MVEM and optimal control. It is shown that whether the optimal solution exhibits periodic oscillations or not is operating point dependent, but is not due to the instantaneous nature of the controls. Even if an actuator model is added the oscillations persist for reasonable time constants, the frequency of the oscillations is however affected. Further it is shown that the periodic control can be predicted by optimal periodic control theory and that the frequency of the control affects the resulting efficiency.
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