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1.	Aggestam, Emil, 1992, et al. (författare) Simulation of vertical dynamic vehicle–track interaction using a two-dimensional slab track model 2018 Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 1744-5159 .- 0042-3114. ; 56:11, s. 1633-1657 Tidskriftsartikel (refereegranskat)abstract The vertical dynamic interaction between a railway vehicle and a slab track is simulated in the time domain using an extended state-space vector approach in combination with a complex-valued modal superposition technique for the linear, time-invariant and two-dimensional track model. Wheel–rail contact forces, bending moments in the concrete panel and load distributions on the supporting foundation are evaluated. Two generic slab track models including one or two layers of concrete slabs are presented. The upper layer containing the discrete slab panels is described by decoupled beams of finite length, while the lower layer is a continuous beam. Both the rail and concrete layers are modelled using Rayleigh–Timoshenko beam theory. Rail receptances for the two slab track models are compared with the receptance of a traditional ballasted track. The described procedure is demonstrated by two application examples involving: (i) the periodic response due to the rail seat passing frequency as influenced by the vehicle speed and a foundation stiffness gradient and (ii) the transient response due to a local rail irregularity (dipped welded joint).
2.	Albinsson, Anton, 1989, et al. (författare) Design of tyre force excitation for tyre–road friction estimation 2017 Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 1744-5159 .- 0042-3114. ; 55:2, s. 208-230 Tidskriftsartikel (refereegranskat)abstract Knowledge of the current tyre–road friction coefficient is essential for future autonomous vehicles. The environmental conditions, and the tyre–road friction in particular, determine both the braking distance and the maximum cornering velocity and thus set the boundaries for the vehicle. Tyre–road friction is difficult to estimate during normal driving due to low levels of tyre force excitation. This problem can be solved by using active tyre force excitation. A torque is added to one or several wheels in the purpose of estimating the tyre–road friction coefficient. Active tyre force excitation provides the opportunity to design the tyre force excitation freely. This study investigates how the tyre force should be applied to minimise the error of the tyre–road friction estimate. The performance of different excitation strategies was found to be dependent on both tyre model choice and noise level. Furthermore, the advantage with using tyre models with more parameters decreased when noise was added to the force and slip ratio.
3.	Andersson, Robin, 1986, et al. (författare) An efficient approach to the analysis of rail surface irregularities accounting for dynamic train–track interaction and inelastic deformations 2015 Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 1744-5159 .- 0042-3114. ; 53:11, s. 1667-1685 Tidskriftsartikel (refereegranskat)abstract A two-dimensional computational model for assessment of rolling contact fatigue induced by discrete rail surface irregularities, especially in the context of so-called squats, is presented. Dynamic excitation in a wide frequency range is considered in computationally efficient time-domain simulations of high-frequency dynamic vehicle-track interaction accounting for transient non-Hertzian wheel–rail contact. Results from dynamic simulations are mapped onto a finite element model to resolve the cyclic, elastoplastic stress response in the rail. Ratcheting under multiple wheel passages is quantified. In addition, low cycle fatigue impact is quantified using the Jiang–Sehitoglu fatigue parameter. The functionality of the model is demonstrated by numerical examples.
4.	Andersson, Robin, 1986, et al. (författare) The influence of rail surface irregularities on contact forces and local stresses 2015 Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 1744-5159 .- 0042-3114. ; 53:1, s. 68-87 Tidskriftsartikel (refereegranskat)abstract The effect of initial rail surface irregularities on promoting further surface degradation is investi-gated. The study concerns rolling contact fatigue formation, in particular in the form of the so-calledsquats. The impact of surface irregularities in the form of dimples is quantified by peak magnitudesof dynamic contact stresses and contact forces. To this end simulations of two-dimensional (laterextended to three-dimensional) vertical dynamic vehicle–track interaction are employed. The mostinfluencing parameters are identified. It is shown that even very shallow dimples might have a largeimpact on local contact stresses. Peak magnitudes of contact forces and stresses due to the influenceof rail dimples are shown to exceed those due to rail corrugation.
5.	Andreasson, Johan, et al. (författare) Driving Dynamics for Hybrid Electric Vehicles Considering Handling and Control Architecture 2004 Ingår i: Vehicle System Dynamics. - 0042-3114 .- 1744-5159. ; 41, s. 497-506 Tidskriftsartikel (refereegranskat)
6.	Andreasson, Johan, et al. (författare) Global Chassis Control Based on Inverse Vehicle Dynamics Models 2006 Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 0042-3114 .- 1744-5159. ; 44:supplement s, s. 321-328 Tidskriftsartikel (refereegranskat)abstract This work proposes to approach global chassis control (GCC) by means of model inversion-based feedforward with allocation directly on the actuator commands. The available degrees of freedom are used to execute the desired vehicle motion while minimizing the utilization of the tyre's grip potential. This is done by sampled constrained least-squares optimization of the linearized problem. To compensate for model errors and external disturbances, high-gain feedback is applied by means of an inverse disturbance observer. The presented method is applied in a comparison of eight vehicles with different actuator configurations for steer, drive, brake and load distribution. The approach shows a transparent and effective method to deal with the complex issue of GCC in a unitized way. It gives both a base for controller design and a structured way to compare different configurations. In practice, the transparency supports automatic on-board reconfiguration in the case of actuator hardware failure.
7.	Anistratov, Pavel, et al. (författare) Analysis and design of recovery behaviour of autonomous-vehicle avoidance manoeuvres 2022 Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 0042-3114 .- 1744-5159. ; 60:7, s. 2231-2254 Tidskriftsartikel (refereegranskat)abstract Autonomous vehicles allow utilisation of new optimal driving approaches that increase vehicle safety by combining optimal all-wheel braking and steering even at the limit of tyre–road friction. One important case is an avoidance manoeuvre that, in previous research, for example, has been approached by different optimisation formulations. An avoidance manoeuvre is typically composed of an evasive phase avoiding an obstacle followed by a recovery phase where the vehicle returns to normal driving. Here, an analysis of the different aspects of the recovery phase is presented, and a subsequent formulation is developed in several steps based on theory and simulation of a double lane-change scenario. Each step leads to an extension of the optimisation criterion. Two key results are a theoretical redundancy analysis of wheel-torque distribution and the subsequent handling of it. The overall contribution is a general treatment of the recovery phase in an optimisation framework, and the method is successfully demonstrated for three different formulations: lane-deviation penalty, minimum time, and squared lateral-error norm.
8.	Apezetxea, I. S., et al. (författare) Modelling stochastic excitations for a fast wear calculation methodology 2020 Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 0042-3114 .- 1744-5159. ; 58:11, s. 1657-1674 Tidskriftsartikel (refereegranskat)abstract Modelling and simulation of wheel profile evolution is a time-consuming process in which the variables that affect simulation cases are usually selected and tuned through an iterative process, in order to find the right setup for a specific case. In a previous work, a fast and reliable methodology for wear prediction was developed, systematic and applicable in general terms for any arbitrary network, vehicle fleet or operating conditions. Here variables that influence the running behaviour of the vehicle along a track were classified into two groups (deterministic or statistical), according to the kind of method to be used to consider them in the wear calculation process. The deterministic method was already defined in [1], while this paper focuses on the definition of the statistical method. This methodology is illustrated through the study of track irregularities: first, their actual effect on wear is analysed and then, their representation as stochastic variables in the developed methodology is presented. The whole methodology is based on quasi-static simulations instead of dynamic simulations for calculating the wheel-rail contact parameters, so a special effort is made in ensuring that, when these parameters are defined by a statistical method, the methodology for wear estimation continues being valid.
9.	Apezetxea, I. S., et al. (författare) New methodology for fast prediction of wheel wear evolution 2017 Ingår i: Vehicle System Dynamics. - : Taylor and Francis Ltd.. - 0042-3114 .- 1744-5159. ; 55:7, s. 1071-1097 Tidskriftsartikel (refereegranskat)abstract In railway applications wear prediction in the wheel–rail interface is a fundamental matter in order to study problems such as wheel lifespan and the evolution of vehicle dynamic characteristic with time. However, one of the principal drawbacks of the existing methodologies for calculating the wear evolution is the computational cost. This paper proposes a new wear prediction methodology with a reduced computational cost. This methodology is based on two main steps: the first one is the substitution of the calculations over the whole network by the calculation of the contact conditions in certain characteristic point from whose result the wheel wear evolution can be inferred. The second one is the substitution of the dynamic calculation (time integration calculations) by the quasi-static calculation (the solution of the quasi-static situation of a vehicle at a certain point which is the same that neglecting the acceleration terms in the dynamic equations). These simplifications allow a significant reduction of computational cost to be obtained while maintaining an acceptable level of accuracy (error order of 5–10%). Several case studies are analysed along the paper with the objective of assessing the proposed methodology. The results obtained in the case studies allow concluding that the proposed methodology is valid for an arbitrary vehicle running through an arbitrary track layout.
10.	Arikere, Adithya, 1987, et al. (författare) Integrated evasive manoeuvre assist for collision mitigation with oncoming vehicles 2018 Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 1744-5159 .- 0042-3114. ; 56:10, s. 1577-1603 Tidskriftsartikel (refereegranskat)abstract Development and deployment of steering based collision avoidance systems are made difficult due to the complexity of dealing with oncoming vehicles during the evasive manoeuvre. A method to mitigate the collision risk with oncoming vehicles during such manoeuvres is presented in this work. A point mass analysis of such a scenario is first done to determine the importance of speed for mitigating the collision risk with the oncoming vehicle. A characteristic parameter was identified, which correlates well with the need to increase or decrease speed, in order to reduce the collision risk. This finding was then verified in experiments using a Volvo XC90 test vehicle. A closed-loop longitudinal acceleration controller for collision mitigation with oncoming vehicles is then presented. The longitudinal control is combined with yaw stability control using control allocation to form an integrated controller. Simulations in CarMaker using a validated XC90 vehicle model and the proposed controller showed consistent reductions in the collision risk with the oncoming vehicle.
11.	Arikere, Adithya, 1987, et al. (författare) Optimal motion control for collision avoidance at Left Turn Across Path/Opposite Direction intersection scenarios using electric propulsion 2019 Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 1744-5159 .- 0042-3114. ; 57:5, s. 637-664 Tidskriftsartikel (refereegranskat)abstract Collision avoidance at intersections involving a host vehicle turning left across the path of an oncoming vehicle (Left Turn Across Path/Opposite Direction or LTAP/OD) have been studied in the past, but mostly using simplified interventions and rarely considering the possibility of crossing the intersection ahead of a bullet vehicle. Such a scenario where the driver preference is to avoid a collision by crossing the intersection ahead of a bullet vehicle is considered in this work. The optimal vehicle motion for collision avoidance in this scenario is determined analytically using a particle model within an optimal control framework. The optimal manoeuvres are then verified through numerical optimisations using a two-track vehicle model, where it was seen that the wheel forces followed the analytical global force angle result independently of the other wheels. A Modified Hamiltonian Algorithm (MHA) controller for collision avoidance that uses the analytical optimal control solution is then implemented and tested in CarMaker simulations using a validated Volvo XC90 vehicle model. Simulation results showed that collision risk can be significantly reduced in this scenario using the proposed controller, and that more benefit can be expected in scenarios that require larger speed changes.
12.	Arnold, Martin, et al. (författare) Numerical methods in vehicle system dynamics: state of the art and current developments 2011 Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 1744-5159 .- 0042-3114. ; 49:7, s. 1159-1207 Tidskriftsartikel (refereegranskat)abstract Robust and eﬃcient numerical methods are an essential prerequisite for the computer based dynamical analysis of engineering systems. In vehicle system dynamics, the methods and software tools from multibody system dynamics provide the integration platform for the analysis, simulation and optimization of the complex dynamical behaviour of vehicles and vehicle components and their interaction with hydraulic components, electronical devices and control structures. Based on the principles of classical mechanics, the modelling of vehicles and their components results in nonlinear systems of ordinary differential equations (ODEs) or differential-algebraic equations (DAEs) of moderate dimension that describe the dynamical behaviour in the frequency range required and with a level of detail being characteristic of vehicle system dynamics. Most practical problems in this ﬁeld may be transformed to generic problems of numerical mathematics like systems of nonlinear equations in the (quasi-)static analysis and explicit ODEs or DAEs with a typical semi-explicit structure in the dynamical analysis. This transformation to mathematical standard problems allows to use sophisticated, freely available numerical software that is based on well approved numerical methods like the Newton-Raphson iteration for nonlinear equations or Runge-Kutta and linear multistep methods for ODE/DAE time integration. Substantial speed-ups of these numerical standard methods may be achieved exploiting some speciﬁc structure of the mathematical models in vehicle system dynamics. In the present paper, we follow this framework and start with some modelling aspects being relevant from the numerical viewpoint. The focus of the paper is on numerical methods for static and dynamic problems including software issues and a discussion which method ﬁts best for which class of problems. Adaptive components in state-of-the-art numerical software like stepsize and order control in time integration are introduced and illustrated by a well known benchmark problem from rail vehicle simulation. Over the last few decades, the complexity of high-end applications in vehicle system dynamics has frequently given a fresh impetus for substantial improvements of numerical methods and for the development of novel methods for new problem classes. In the present paper, we address three of these challenging problems of current interest that are today still beyond the mainstream of numerical mathematics: (i) Modelling and simulation of contact problems in multibody dynamics, (ii) Real-time capable numerical simulation techniques in vehicle system dynamics and iii) Modelling and time integration of multidisciplinary problems in system dynamics including co-simulation techniques.
13.	Askerdal, Mikael, 1975, et al. (författare) Development of simplified air drag models including crosswinds for commercial heavy vehicle combinations 2024 Ingår i: Vehicle System Dynamics. - 1744-5159 .- 0042-3114. ; 62:5, s. 1085-1102 Tidskriftsartikel (refereegranskat)abstract Accurate range prediction requires good knowledge of the prevailing wind conditions and how they affect the energy consumption of the ego vehicle. A few different simplified vehicle air drag models that explicitly include the effect from crosswinds are presented and compared through some objective criteria. The models are developed from the normal air drag equation where the effect from wind is implicit and therefore often forgotten or neglected. The purpose is to find a low-complexity model complementing CFD models and wind tunnel tests, that can be used for range estimation and predictive energy management algorithms. To simplify online estimation, a requirement is that the air drag models only contain a few tuning parameters. The models are validated against CFD calculations for a few vehicle combinations and the best models show good accuracy for air attack angles up to at least 60 degrees. It is shown that the parameters of the simplified models can loosely be connected to some basic geometrical attributes of a vehicle combination so it should be possible to give at least a rough estimate of the parameters of a simplified model based on these geometrical attributes. This is useful for making a first estimate of the aerodynamic properties of a vehicle combination after major changes in the exterior, e.g. when adding a trailer. It also highlights that the size and the shape of the vehicle side may be mainly responsible for the high longitudinal air drag sensitivity to crosswinds for large vehicle combinations.
14.	Askerdal, Mikael, 1975, et al. (författare) Motion resistance modelling and validation in winter conditions with varying air drag 2024 Ingår i: Vehicle System Dynamics. - 1744-5159 .- 0042-3114. ; In Press Tidskriftsartikel (refereegranskat)abstract Range prediction is vital for battery electric vehicles, and the main source of errors in range prediction is often the uncertainty in motion resistance. Rig and wind tunnel measurements can be used to find the motion resistance of a specific vehicle combination under specified weather conditions. However, real-life variation of the operating conditions of heavy-duty vehicles makes testing impractical. This paper proposes and validates a model of motion resistance with parameters adapted to actual road weather conditions. The model is validated in winter conditions with varying wind, using a vehicle equipped with a wind sensor. The results show that the proposed model captures the motion resistance with high accuracy. Results also indicate that it is crucial to take weather effects into account when modelling motion resistance, particularly in winter conditions.
15.	Berghuvud, Ansel, et al. (författare) Consequences of nonlinear characteristics of a secondary suspension in a three-piece freight car bogie 2001 Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 0042-3114 .- 1744-5159. ; 36:1, s. 37-55 Tidskriftsartikel (refereegranskat)abstract Mechanical systems with nonlinear characteristics can show a complex dynamic behavior that should be taken into account when analysing dynamic performance and reliability. The dynamic behavior of the main suspension in a three-piece freight car bogie with constant friction damping is considered in this work. The aim is to investigate the vertical behavior of a specific suspension design due to different driving conditions, weather and wear of the friction wedges. A variation in weather and wear is represented by different friction configurations in the model of the suspension. Models of different levels of detail that are based on experimental data on existing designs are developed. It is found that the suspension performance is very sensitive to variations of the friction configuration and this indicates a possible presence of nonlinear dynamic phenomena at in service like conditions
16.	Berghuvud, Ansel, et al. (författare) Dynamic behaviour of ore wagons in curves at Malmbanan 1998 Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 0042-3114 .- 1744-5159. ; 30:3-4, s. 271-284 Tidskriftsartikel (refereegranskat)abstract The transportation of ore can be made more cost efficient by use of bigger and heavier trains. An increase in axle load is thereby wanted. The fleet of ore wagons of today at Malmbanan/Ofotbanan in northern Sweden and Norway has to be updated. It is of interest to find out if it is possible to allow a higher axle load on the track with new wagons. To be able to understand and predict the effects on track wear depending on what type of vehicle that is in use, the contact forces between wheels and rails have to be determined. A computer aided analysis has been made of the dynamic behaviour of three test vehicles equipped with different types of three-piece bogies running at Malmbanan. The vehicles are modelled and their interaction with the track is analyzed using the multibody simulation package GENSYS. The simulations show that, even if the axle load is increased from 25 tons to 30 tons and the velocity is increased from 50 km/h to 60 km/h, it is possible to reduce lateral track forces and wear in curves by using a different bogie than the standard three-piece bogie used today
17.	Berntorp, Karl, et al. (författare) Models and methodology for optimal trajectory generation in safety-critical road–vehicle manoeuvres 2014 Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 1744-5159 .- 0042-3114. ; 52:10, s. 1304-1332 Tidskriftsartikel (refereegranskat)abstract There is currently a strongly growing interest in obtaining optimal control solutions for vehicle manoeuvres, both in order to understand optimal vehicle behaviour and, perhaps more importantly, to devise improved safety systems, either by direct deployment of the solutions or by including mimicked driving techniques of professional drivers. However, it is non-trivial to find the right combination of models, optimisation criteria, and optimisation tools to get useful results for the above purposes. Here, a platform for investigation of these aspects is developed based on a state-of-the-art optimisation tool together with adoption of existing vehicle chassis and tyre models. A minimum-time optimisation criterion is chosen for the purpose of gaining an insight into at-the-limit manoeuvres, with the overall aim of finding improved fundamental principles for future active safety systems. The proposed method to trajectory generation is evaluated in time-manoeuvres using vehicle models established in the literature. We determine the optimal control solutions for three manoeuvres using tyre and chassis models of different complexities. The results are extensively analysed and discussed. Our main conclusion is that the tyre model has a fundamental influence on the resulting control inputs. Also, for some combinations of chassis and tyre models, inherently different behaviour is obtained. However, certain variables important in vehicle safety-systems, such as the yaw moment and the body-slip angle, are similar for several of the considered model configurations in aggressive manoeuvring situations.
18.	Bezin, Yann, et al. (författare) Multibody simulation benchmark for dynamic vehicle-track interaction in switches and crossings: modelling description and simulation tasks 2023 Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 1744-5159 .- 0042-3114. ; 61:3, s. 644-659 Tidskriftsartikel (refereegranskat)abstract This paper presents the final description for the S&C Benchmark that was launched at the IAVSD 2019 conference held in Gothenburg, Sweden and completed by eighteen participants by the end of 2020. The purpose of this paper is to allow for the replication of the Benchmark exercise after publication for those who wish to do so in the future, and it includes a link to the repository containing all necessary input data. The original task description, including a description of the Benchmark submission, is presented in full. The results from the Benchmark are available in [Bezin Y, Pålsson BA, Kik W, et al. Multibody simulation Benchmark for dynamic vehicle-track interaction in switches and crossings: results and method statements. Submitted to VSD, 2021].
19.	Bezin, Y., et al. (författare) Multibody simulation benchmark for dynamic vehicle-track interaction in switches and crossings: results and method statements 2023 Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 1744-5159 .- 0042-3114. ; 61:3, s. 660-697 Tidskriftsartikel (refereegranskat)abstract A Benchmark of railway multibody dynamics software application to switches and crossings (S&C) is presented, comparing all major commercially available software and a few independent codes. Two different representative S&C have been implemented, using the Manchester Benchmark passenger vehicle. The final results show that all software offer a reliable and efficient way to understand the kinematic and dynamics forces between the wheels and the track elements. The highest challenges are found when modelling a combination of multiple rails in simultaneous contact with a wheel (check-stock or switch-stock), large longitudinal variations in rail shape (crossings) and high lateral steering forces (diverging cases in tight radius). In those cases, the codes able to account for the exact relative motion of each wheels with respect to each rails independently are the most apt. The most significant variations between software are found in the contact prediction with an influence on the detailed contact tangential and normal forces. The user variability is found to be very small, with the most time-consuming and error prone being the task of handling the input data for the variable rails definition. All software could benefit from improvements to assist the user and ensure higher reliability and efficiency generally.
20.	Blanco, Blas, et al. (författare) Distributed support modelling for vertical track dynamic analysis 2018 Ingår i: Vehicle System Dynamics. - : Taylor & Francis. - 0042-3114 .- 1744-5159. ; 56:4, s. 529-552 Tidskriftsartikel (refereegranskat)abstract The finite length nature of rail-pad supports is characterised by a Timoshenko beam element formulation over an elastic foundation, giving rise to the distributed support element. The new element is integrated into a vertical track model, which is solved in frequency and time domain. The developed formulation is obtained by solving the governing equations of a Timoshenko beam for this particular case. The interaction between sleeper and rail via the elastic connection is considered in an analytical, compact and efficient way. The modelling technique results in realistic amplitudes of the pinned-pinned' vibration mode and, additionally, it leads to a smooth evolution of the contact force temporal response and to reduced amplitudes of the rail vertical oscillation, as compared to the results from concentrated support models. Simulations are performed for both parametric and sinusoidal roughness excitation. The model of support proposed here is compared with a previous finite length model developed by other authors, coming to the conclusion that the proposed model gives accurate results at a reduced computational cost.
21.	Blanco, Blas, et al. (författare) Implementation of Timoshenko element local deflection for vertical track modelling 2019 Ingår i: Vehicle System Dynamics. - : TAYLOR & FRANCIS LTD. - 0042-3114 .- 1744-5159. ; 57:10, s. 1421-1444 Tidskriftsartikel (refereegranskat)abstract A vertical track model suitable for the study of the dynamic response and the interaction between wheel and rail in the time domain is developed by using Timoshenko beam elements, and its performance is optimised by accounting for the local deflection of these type of elements. Implementation of the local system enables one to obtain an accurate description of the contact force in a more computationally efficient way than other numerical methods, and it leads to an almost total elimination of the discontinuities caused by the local displacement underestimation and the shear incompatibilities introduced by the conventional formulation with Timoshenko beam elements. The work presented here describes both static and dynamic approaches of the local system directly obtained through the resolution of the beam governing equations. The dynamic approach guarantees the shear rotation continuity and describes accurately the track frequency content. The method is tested for parametric excitation, in which it ensures the smoothness of the response. Secondly, it is tested for short-pitch corrugated rails, where overestimation of the contact force is avoided with a reduced model size when compared with conventional Timoshenko element formulation. The results are validated by comparison with those from previous studies.
22.	Blanco, B., et al. (författare) On the correction of rail accelerations predicted by numerical track models based on Timoshenko beam theory 2021 Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 0042-3114 .- 1744-5159. ; , s. 1-25 Tidskriftsartikel (refereegranskat)abstract Rail accelerations can be used on the defect detection and health monitoring of railway vehicle and track components; therefore, mathematical models that predict this response are of interest for reproducing its behaviour in a wide range of situations. The numerical track models based on the Timoshenko beam theory introduce a non-physical response, which is especially noticeable in the rail accelerations. It is due to the lack of dynamic convergence of the Timoshenko finite element (FE). This paper addresses this phenomenon employing an enhanced formulation of the Timoshenko FE that includes internal degrees of freedom (iDoF). The iDoF shape functions are derived from the Timoshenko beam dynamic governing equations. Firstly, the formulation is presented, and its performance is compared with a similar Timoshenko FE formulation. Secondly, the proposal is assessed in the dynamic modelling of railway track structures. The use of iDoF efficiently corrects the non-physical response of rail accelerations by improving the FE dynamic convergence. Subsequently, a filtering criterion for accelerations is proposed, which removes the remaining non-physical response while guaranteeing the conservation of coherent frequency content. Finally, practical cases are simulated for which the proposed methodology is proved to be more efficient and reliable than the standard approach.
23.	Bogsjö, Klas (författare) Development of analysis tools and stochastic models of road profiles regarding their influence on heavy vehicle fatigue 2006 Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 1744-5159 .- 0042-3114. ; 44:S1, s. 780-790 Tidskriftsartikel (refereegranskat)abstract Road profiles are analyzed with focus on road characteristics essential for heavy vehicle fatigue assessment. Road profile measurements indicate that roads contain short sections with above-average irregularity. Such rough sections are shown to cause most of the vehicle fatigue damage. An algorithm using a spatial-frequency description is developed to automatically identify rough sections. On the basis of the analysis, a new stochastic road model, with randomly placed and randomly shaped irregularities, is proposed.
24.	Bogsjö, Klas, et al. (författare) Models for road surface roughness 2012 Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 0042-3114 .- 1744-5159. ; 50:5, s. 725-747 Tidskriftsartikel (refereegranskat)abstract This study focuses on the statistical description and analysis of road surface irregularities that are essential for heavy-vehicle fatigue assessment. Three new road profile models are proposed: a homogenous Laplace moving average process, a non-homogenous Laplace process and a hybrid model that combines Gaussian and Laplace modelling. These are compared with the classical homogenous Gaussian process as well as with the non-homogenous Gaussian model that represents the road surface as a homogenous Gaussian process with Motor Industry Research Association spectrum enhanced by randomly placed and shaped irregularities. The five models are fitted to eight measured road surfaces and their accuracy and efficiency are discussed.
25.	Brabie, Dan, et al. (författare) Dynamic simulation of derailments and its consequences 2006 Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 0042-3114 .- 1744-5159. ; 44:Suppl 1, s. 652-662 Tidskriftsartikel (refereegranskat)abstract This article describes the necessary prerequisites and methodology in progress for studying train vehicle derailments and means of minimising the risk of catastrophic consequences. A comprehensive model has been developed and used in the multi-body system (MBS) simulation software for studying pre- and post-derailment vehicle behaviour. An axle-mounted brake disc and vertically extended bogie frames have shown empirically, as well as by MBS simulations, a potential to favourably influence the sequence of events in case of wheel flange climbing derailments. The MBS simulation methodology has been presented. Examples of how critical geometrical parameters affect the ability of these mechanisms to act as substitute guidance are presented. Further, a finite element (FE) model is developed for studying the impact phenomenon between a rail vehicle wheel and concrete sleepers. In particular, the proposed FE model will be used for obtaining hysteresis data for the wheel-sleeper force as functions of concrete indentation, for further development of the MBS simulations technique.
26.	Brabie, Dan, et al. (författare) Post-derailment dynamic simulation of rail vehicles : Methodology and applications 2008 Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 0042-3114 .- 1744-5159. ; 46:Suppl. S, s. 289-300 Tidskriftsartikel (refereegranskat)abstract An earlier developed multi-body system post-derailment module. that predicts the wheelsets' behaviour after impact with concrete sleepers, is upgraded to account for possible wheel-rail fastener impact after train derailments at high speed. The vertical stiffness describing the wheel-fastener impact behaviour is calibrated and validated based on two authentic derailment cases. Geometrical specifications that permit it brake disc and a bogie frame to act as substitute guidance mechanisms after Hart e climbing derailments on Curved track are presented for an X 2000 trailer car. Further, an introductory analysis on the post-derailment vehicle behaviour on tangent track after a 'flange on rail head' derailment condition is also presented its a function of bogie yaw resistance. The risk of carbody overturning after derailments on tangent track is assessed as a function of coupler height and carbody centre of gravity as well as bogie transversal beam position.
27.	Brandt, Adam, 1993, et al. (författare) High speed driving stability of road vehicles under crosswinds: an aerodynamic and vehicle dynamic parametric sensitivity analysis 2022 Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 1744-5159 .- 0042-3114. ; 60:7, s. 2334 -2357 Tidskriftsartikel (refereegranskat)abstract Crosswinds affect vehicle driving stability and their influence increase with driving speed. To improve high speed driving stability, interdisciplinary research using unsteady aerodynamics and vehicle dynamics is necessary. The current demands of faster development times require robust virtual methods for assessing stability performance in early design phases. This paper employs a numerical one-way coupling between the two disciplines and uses a variety of realistic crosswind gust profiles for the aerodynamic simulations to output representative forces and moments on three vehicle dynamic models of different fidelity levels, ranging from a one-track model to a full multi-body dynamic model of a sports utility vehicle. An investigation on required model fidelity was conducted along with a sensitivity study to find key aerodynamic and vehicle dynamic characteristics to minimise the yaw velocity and lateral acceleration response during crosswinds. Transient aerodynamic simulations were used to model crosswind gusts at high speeds. Analysis of the forces and moments showed that rapid changing gusts generate overshoots in the yaw moment, due to the phase delay of the flow between the front and rear of the vehicle. A methodology for modelling this phase delay is proposed. The response of the vehicle was captured equally well by the enhanced model (mid-level fidelity) and the full multi-body dynamic model, while the simplest one-track model failed to emulate the correct vehicle response. The sensitivity study showed the importance of the positioning of the centre of gravity, the aerodynamic coefficient of yaw moment, wheel base, vehicle mass and yaw inertia. In addition, the axles' side force steer gradients and other suspension parameters revealed potential in improving crosswind stability.
28.	Bruni, Stefano, et al. (författare) Modelling of suspension components in a rail vehicle dynamics context 2011 Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 0042-3114 .- 1744-5159. ; 49:7, s. 1021-1072 Tidskriftsartikel (refereegranskat)abstract Suspension components play key roles in the running behaviour of rail vehicles, and therefore, mathematical models of suspension components are essential ingredients of railway vehicle multi-body models. The aims of this paper are to review existing models for railway vehicle suspension components and their use for railway vehicle dynamics multi-body simulations, to describe how model parameters can be defined and to discuss the required level of detail of component models in view of the accuracy expected from the overall simulation model. This paper also addresses track models in use for railway vehicle dynamics simulations, recognising their relevance as an indispensable component of the system simulation model. Finally, this paper reviews methods presently in use for the checking and validation of the simulation model.
29.	Bruni, Stefano, et al. (författare) The results of the pantograph-catenary interaction benchmark 2015 Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 0042-3114 .- 1744-5159. ; 53:3, s. 412-435 Tidskriftsartikel (refereegranskat)abstract This paper describes the results of a voluntary benchmark initiative concerning the simulation of pantograph-catenary interaction, which was proposed and coordinated by Politecnico di Milano and participated by 10 research institutions established in 9 different countries across Europe and Asia. The aims of the benchmark are to assess the dispersion of results on the same simulation study cases, to demonstrate the accuracy of numerical methodologies and simulation models and to identify the best suited modelling approaches to study pantograph-catenary interaction. One static and three dynamic simulation cases were defined for a non-existing but realistic high-speed pantograph-catenary couple. These cases were run using 10 of the major simulation codes presently in use for the study of pantograph-catenary interaction, and the results are presented and critically discussed here. All input data required to run the study cases are also provided, allowing the use of this benchmark as a term of comparison for other simulation codes.
30.	Bruzelius, Fredrik, 1974- (författare) A theoretical justification of the sine with dwell manoeuvre 2015 Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 0042-3114 .- 1744-5159. ; 53:4, s. 493-505 Tidskriftsartikel (refereegranskat)abstract The sine with dwell (SWD) manoeuvre has received much attention within the context of vehicle stability testing. This manoeuvre is used in a test developed by the NHTSA, designed to certificate electronic stability control systems in light vehicles. The test is used in legislations as well as in consumer tests all over the globe. The SWD manoeuvre was designed using test vehicles on a test track and experimentally validated. The paper at hand uses optimal control theory to theoretically justify the use of the SWD manoeuvre to produce a severe lateral motion and over-steering based on steering input. It is shown that a manoeuvre similar to the SWD manoeuvre can be obtained from an optimal control problem using simple vehicle dynamics models. The optimal control method is further used to analyse the manoeuvre's robustness with respect to vehicle dimensions and tyre properties. It is shown that the manoeuvre is robust in dimensions, which theoretically motivates its application for various sizes of vehicles.
31.	Bucca, Giuseppe, et al. (författare) Adoption of different pantographs' preloads to improve multiple collection and speed up existing lines 2012 Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 0042-3114 .- 1744-5159. ; 50:SUPPL. 1, s. 403-418 Tidskriftsartikel (refereegranskat)abstract The current collection using more than one pantograph is needed in railway operation to provide power to non-electrically connected traction units and, in some cases, to reduce current density on the collector strips that heavily influences the wear on the contacting bodies. The multiple current collection may become a critical condition due to the mechanical disturbances produced on the trailing pantographs by the interaction between the first pantograph and the catenary. The present-day evolution of pantograph preload regulating systems, exploiting pressure-controlled servo-valves driven by electronic units, allows a diversification of the preloads of front and rear pantographs. In this work, a suitable solution to improve multiple pantograph collection quality is analysed by the use of a lower mean force on the leading pantograph aimed at reducing the oscillations of contact wire the trailing pantograph is subjected to. This would improve the current collection quality of the trailing pantograph, and could be pursued even admitting a slight worsening of front pantograph's performances.
32.	Burgelman, Nico, et al. (författare) Influence of wheel-rail contact modelling on vehicle dynamic simulation 2015 Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 0042-3114 .- 1744-5159. ; 53:8, s. 1190-1203 Tidskriftsartikel (refereegranskat)abstract This paper presents a comparison of four models of rolling contact used for online contact force evaluation in rail vehicle dynamics. Until now only a few wheel-rail contact models have been used for online simulation in multibody software (MBS). Many more models exist and their behaviour has been studied offline, but a comparative study of the mutual influence between the calculation of the creep forces and the simulated vehicle dynamics seems to be missing. Such a comparison would help researchers with the assessment of accuracy and calculation time. The contact methods investigated in this paper are FASTSIM, Linder, Kik-Piotrowski and Stripes. They are compared through a coupling between an MBS for the vehicle simulation and Matlab for the contact models. This way the influence of the creep force calculation on the vehicle simulation is investigated. More specifically this study focuses on the influence of the contact model on the simulation of the hunting motion and on the curving behaviour.
33.	Carlbom, P., et al. (författare) Passengers, seats and carbody in rail vehicle dynamics 2002 Ingår i: Vehicle System Dynamics. - 0042-3114 .- 1744-5159. ; 37, s. 290-300 Tidskriftsartikel (refereegranskat)abstract Reliable models of passengers, seats and carbody are essential in order predict ride comfort of rail vehicles. This paper extends previously presented models of passenger-carbody interaction to include vertical seating dynamics. The proposed basic model is based on experimental modal analysis of a rail vehicle with and without passengers. The nations of human-body normalized apparent mass and seat transmissibility are fundamental an the modelling. The possibility of using reduced and approximate gels is also discussed in the paper. The proposed models are easy to use and implemented in commercial rail vehicle software.
34.	Casanueva, Carlos, 1981-, et al. (författare) Influence of switches and crossings on wheel profile evolution in freight vehicles 2014 Ingår i: Vehicle System Dynamics. - : Taylor & Francis. - 0042-3114 .- 1744-5159. ; 52:SI, s. 317-337 Tidskriftsartikel (refereegranskat)abstract Wheel reprofiling costs for freight vehicles are a major issue in Sweden, reducing the profitability of freight traffic operations and therefore hindering the modal shift needed for achieving reduced emissions. In order to understand the damage modes in freight vehicles, uniform wear prediction with Archard's wear law has been studied in a two-axle timber transport wagon, and simulation results have been compared to measurements. Challenges of wheel wear prediction in freight wagons are discussed, including the influence of block brakes and switches and crossings. The latter have a major influence on the profile evolution of this case study, so specific simulations are performed and a thorough discussion is carried out.
35.	Chaar, Nizar, et al. (författare) Experimental and numerical modal analyses of a loco wheelset 2004 Ingår i: Vehicle System Dynamics. - 0042-3114 .- 1744-5159. ; 41:Suppl., s. 597-606 Tidskriftsartikel (refereegranskat)abstract Wheelset structural flexibility is believed to have a major influence on the vehicle-track dynamics. Several studies have related the structural flexibility of the wheelset to fluctuations of wheel-rail forces, rail and wheel corrugation, etc. This paper reports part of an ongoing project that studies the effects of wheelset structural flexibility on the vehicle-track dynamics. The paper focuses on experimental and numerical modal analyses of a loco wheelset in the frequency range of 0-500 Hz. Major issues related to modal analyses and modelling of wheelset are presented along with respective results. The results from numerical modal analysis were in good agreement with those obtained from the experiment. In addition, the wheelset had fairly low eigenfrequencies. Reduced versions of the generated wheelset model will be used in coming work in on-track numerical simulations in order to determine the effects of wheelset structural flexibility on the vehicle-track dynamics. Results from these simulations will be validated against existing experimental on-track results.
36.	Chaar, Nizar, et al. (författare) Simulation of vehicle-track interaction with flexible wheelsets, moving track models and field tests 2006 Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 0042-3114 .- 1744-5159. ; 44:Suppl., s. 921-931 Tidskriftsartikel (refereegranskat)abstract Vehicle-track dynamic interaction emerged as a key multi-aspect subject following the development in high-speed and high axle-load trains. In this context. wheelset structural flexibility and track flexibility are the two main factors that contribute to high frequency content of the wheel-rail forces and influence the vehicle-track damage. Appropriate wheelset and track flexibility models are hence of great importance in pertinent numerical simulations. The present study comprises vehicle-track dynamic simulations considering wheelset structural flexibility and advanced moving track models. Simulated wheel-rail forces are then validated against measured data. The effects of the wheelset structural flexibility and track flexibility on the wheel-rail forces are investigated in the frequency range 0-150 Hz. The influence of track modelling and pertinent data on the simulation results is particularly assessed through a set of moving track models. Measured track data, i.e. irregularities, roughness and flexibility support the simulations. It is confirmed that track flexibility with appropriate modelling and data is important when examining the vehicle-track interaction. In the present case study, the influence of wheelset structural flexibility on the lateral wheel-rail forces is quite significant too.
37.	Chugh, Tushar, 1989, et al. (författare) An approach to develop haptic feedback control reference for steering systems using open-loop driving manoeuvres 2020 Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 1744-5159 .- 0042-3114. ; 58:12, s. 1953-1976 Tidskriftsartikel (refereegranskat)abstract In this paper, a methodology to capture the model-based haptic feedback control reference for closed-loop steering systems is demonstrated. The parameterisation is based on the measurements of open-loop driving manoeuvres for the inertia-spring-damper-friction reference model. The steady-state and transient manoeuvres are used to identify the model parameters. The reference model is limited to the haptic feedback of driver excitation in the linear vehicle handling range and intended to be used in closed-loop steering control strategies. The model parameters have an intuitive interpretation that allows to be used in both admittance and impedance control setting. The feasibility of the proposed model is demonstrated in a validated simulation environment for electric power assisted steering and on a real hardware for the steer-by-wire force-feedback case.
38.	Conde Mellado, Alberto, et al. (författare) A lateral active suspension for conventional railway bogies 2009 Ingår i: Vehicle System Dynamics. - : Taylor & Francis. - 0042-3114 .- 1744-5159. ; 47:1, s. 1-14 Tidskriftsartikel (refereegranskat)abstract The present paper describes an active centring system for railway vehicles. The proposed solution is based on lateral pneumatic actuators placed between bogie and car body connected to the vertical secondary suspension air springs. The objective of the developed centring system is twofold: the improvement of the curving behaviour of the train and the decrease of the lateral acceleration perceived by the passenger in curve negotiation thanks to the reduction of the ‘souplesse’ coefficient. The system is described in detail in the paper. Results from simulations are included considering a bidimensional model of the vehicle, and a detailed model of the air spring and control valves. The performance in curve negotiation of a vehicle equipped with this system and a conventional one is compared. Specifically, lateral displacements of the secondary suspension, roll angle and lateral accelerations are analysed. The results show noticeable performance improvements in the vehicle curving behaviour. The proposed centring system can be implemented in a conventional bogie without special design requirements; and due to the low air consumption, additional pressurised reservoirs are not required.
39.	Dahlberg, Tore (författare) Catenary, pantograph, and their interaction 2006 Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 0042-3114 .- 1744-5159. ; 44:8 Annan publikation (övrigt vetenskapligt/konstnärligt)
40.	Dahlberg, Tore, 1945- (författare) Catenary, pantograph, and their interaction 2006 Ingår i: Vehicle System Dynamics. - 0042-3114 .- 1744-5159. ; 44:8, s. 591-593 Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
41.	Dahlberg, Tore, 1945- (författare) Moving force on an axially loaded beam - With applications to a railway overhead contact wire 2006 Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 0042-3114 .- 1744-5159. ; 44:8, s. 631-644 Tidskriftsartikel (refereegranskat)abstract Using modal analysis, the deflection of a beam subjected to an axial tensile force N and a moving vertical force P , has been determined. This solution was exploited in a study of deflection and wave propagation in the contact wire of a railway overhead catenary system. For moderate values of speed c of the moving force P ( i.e ., c less than half the lowest critical speed c crit ) travelling waves reflect at the boundaries of the contact wire so that the waves meet and catch up with the moving force several times. In practice, when a pantograph (here modelled by the force P ) touches the contact wire some distance from the end of the wire, waves are sent out both in the forward and backward direction, giving even more reflections and wave interactions with the contact force. These waves will add or subtract to the wire deflection at the point of force application. The stress in the wire due to bending is estimated and it appears to be moderate for the speeds investigated here ( i.e ., for c < 0.5ccrit). Close to the critical speed, however, bending stresses will be significant.
42.	Drugge, Lars, et al. (författare) Aerodynamic loads on buses due to crosswind gusts : extended analysis 2010 Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 0042-3114 .- 1744-5159. ; 48, s. 287-297 Tidskriftsartikel (refereegranskat)abstract The objective of this work is to use inverse simulations on measured vehicle data in order to estimate the aerodynamic loads on a bus when exposed to crosswind situations. Tyre forces, driver input, wind velocity and vehicle response were measured on a typical coach when subjected to natural crosswind gusts. Based on these measurements and a detailed MBS vehicle model, the aerodynamic loads were estimated through inverse simulations. In order to estimate the lift force, roll and pitch moments in addition to the lateral force and yaw moment, the simulation model was extended by also incorporating the estimation of the vertical road disturbances. The proposed method enables the estimation of aerodynamic loads due to crosswind gusts without using a full scale wind tunnel adapted for crosswind excitation.
43.	Drugge, Lars, et al. (författare) Modelling and simulation of catenary-pantograph interaction 2000 Ingår i: Vehicle System Dynamics. - : Taylor & Francis Ltd.. - 0042-3114 .- 1744-5159. ; 33:suppl, s. 490-501 Tidskriftsartikel (refereegranskat)abstract Modelling and simulation of the dynamic behaviour of catenary-pantograph interaction is an important part when assessing the capability of a current collection system for railway traffic. The large variation in infrastructure characteristics in different countries and railway companies, different types of traffic, designs of pantographs etc. makes it almost impossible to develop a final simulation model of such a system. Instead, it would be favourable to have a tool that has the ability to set up models of such systems, choose relevant detail of the models, run simulations and finally visualize the results. To make the tool useful for engineers, design experts as well as simulation experts, the functionality of the tool must be worked out. Aspects on computer simulation such as developed models, simulation methods and computer tools are presented. The aim is to develop a scenario that considers different designs, models, solution methods and user levels. The scenario focuses on how to structure the use of simulation of dynamics in catenary-pantograph development. A scenario is sketched built on different user levels, a modular structure and a structure for information management
44.	Drugge, Lars, et al. (författare) Modelling and simulation of catenary-pantograph interaction 2000 Ingår i: Vehicle System Dynamics. - 0042-3114 .- 1744-5159. ; 33, s. 202-213 Tidskriftsartikel (refereegranskat)
45.	Drugge, Lars, et al. (författare) Modelling and simulation of catenary-pantograph interaction 1999 Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 0042-3114 .- 1744-5159. ; 33:suppl 1, s. 490-501 Tidskriftsartikel (refereegranskat)abstract Modelling and simulation of the dynamic behaviour of catenary-pantograph interaction is an important part when assessing the capability of a current collection system for railway traffic. The large variation in infrastructure characteristics in different countries and railway companies, different types of traffic, designs of pantographs etc. makes it almost impossible to develop a final simulation model of such a system. Instead, it would be favourable to have a tool that has the ability to set up models of such systems, choose relevant detail of the models, run simulations and finally visualize the results. To make the tool useful for engineers, design experts as well as simulation experts, the functionality of the tool must be worked out. Aspects on computer simulation such as developed models, simulation methods and computer tools are presented. The aim is to develop a scenario that considers different designs, models, solution methods and user levels. The scenario focuses on how to structure the use of simulation of dynamics in catenary-pantograph development. A scenario is sketched built on different user levels, a modular structure and a structure for information management
46.	Edrén, Johannes, et al. (författare) Utilisation of optimisation solutions to control active suspension for decreased braking distance 2015 Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 0042-3114 .- 1744-5159. ; 53:2, s. 256-273 Tidskriftsartikel (refereegranskat)abstract This work deals with how to utilise active suspension on individual vehicle wheels in order to improve the vehicle performance during straight-line braking. Through numerical optimisation, solutions have been found as regards how active suspension should be controlled and coordinated with friction brakes to shorten the braking distance. The results show that, for the studied vehicle, the braking distance can be shortened by more than 1 m when braking from 100 km/h. The applicability of these results is studied by investigating the approach for different vehicle speeds and actuator stroke limitations. It is shown that substantial improvements in the braking distance can also be found for lower velocities, and that the actuator strokes are an important parameter. To investigate the potential of implementing these findings in a real vehicle, a validated detailed vehicle model equipped with active struts is analysed. Simplified control laws, appropriate for on-board implementation and based on knowledge of the optimised solution, are proposed and evaluated. The results show that substantial improvements of the braking ability, and thus safety, can be made using this simplified approach. Particle model simulations have been made to explain the underlying physical mechanisms and limitations of the approach. These results provide valuable guidance on how active suspension can be used to achieve significant improvements in vehicle performance with reasonable complexity and energy consumption.
47.	Enblom, Roger (författare) Deterioration mechanisms in the wheel-rail interface with focus on wear prediction : a literature review 2009 Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 0042-3114 .- 1744-5159. ; 47:6, s. 661-700 Forskningsöversikt (refereegranskat)abstract Wheel-rail interface management is imperative to railway operation and its maintenance represents a major share of the total maintenance cost. In general, the course of events usually called wear is a complicated process involving several modes of material deterioration and contact surface alteration. Thus material removal or relocation, plastic flow and phase transformation may take place at, just below, or in-between the contacting surfaces. A higher degree of predictability of deterioration mechanisms and a firm basis for optimisation of the wheel-rail system are anticipated to reveal a great potential for cost savings. Wear in the sense of material loss and related wheel-rail profile evolution represents one of several modes of damage. The purpose of this survey is to explore research on wear simulation, to some degree extended to neighbouring disciplines. It is believed that a cross-disciplinary approach involving, for instance, adhesive and abrasive wear, surface plasticity, and rolling contact fatigue opens new perspectives to improved damage prediction procedures.
48.	Erdinc, Umur, 1992, et al. (författare) Safe operating envelope based on a single-track model for yaw instability avoidance of articulated heavy vehicles 2024 Ingår i: Vehicle System Dynamics. - 1744-5159 .- 0042-3114. ; 62:8, s. 2138-2161 Tidskriftsartikel (refereegranskat)abstract The electrification of commercial vehicles has led to new wheel torque allocation options for propulsion and braking of articulated heavy vehicles. Each unit or axle can be individually braked or propelled whilst the other units or axles are excluded from such action. This may achieve the best energy efficiency. However, this can also lead to potential yaw stability problems such as jackknifing and trailer swing, especially under bad loading and weather conditions. This paper describes the above instabilities and introduces a nonlinear single-track model to study the vehicle dynamics of the tractor-semitrailer combination. The effects of different vehicle and environment parameters are analysed with this vehicle model. A safe operating envelope for limiting the wheel forces is obtained using this vehicle model. Since the vehicle model introduced in this paper is computationally effective, it can be run online in real vehicles, with an instantaneous safe operating envelope obtained for the momentary conditions. Thus, yaw instabilities such as jackknifing and trailer swing may be avoided.
49.	Erdinc, Umur, 1992, et al. (författare) Validation of high-fidelity simulation-based safe operating envelopes for articulated heavy vehicles using real test data 2024 Ingår i: Vehicle System Dynamics. - 1744-5159 .- 0042-3114. ; In Press Tidskriftsartikel (refereegranskat)abstract The electrification of towing and trailing units creates new torque allocation alternatives among different units of articulated heavy vehicles. To increase the power and energy efficiency, control algorithms can request propulsion or regenerative braking from a single unit while keeping the other units unbraked or unpropelled. However, this may lead to safety problems, such as jackknifing or trailer swing. This paper uses a high-fidelity simulation tool to formulate safe operating envelopes for a tractor and semitrailer combination for braking-in-turn cases. The effects of different vehicle and environment parameters on the safe operating envelope are studied. The safe operating envelope obtained is then validated using real vehicle tests and can be used with any control algorithm to avoid requesting unsafe unit force combinations.
50.	Evans, J., et al. (författare) Challenges in simulation of rail vehicle dynamics 2009 Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 0042-3114 .- 1744-5159. ; 47:8, s. 1023-1048 Tidskriftsartikel (refereegranskat)abstract Rail vehicle dynamic simulation has progressed a long way from its origins as a research tool. Modern multibody software packages are used as an essential part of the design process for new vehicles and for investigating service problems with existing vehicles. Increasingly, simulation is being used as part of the vehicle acceptance process in place of on-track testing. This state of the art paper for the 21st IAVSD Symposium in Stockholm in August 2009 surveys the current applications for rail vehicle dynamic modelling. The process of reducing a complex mechanical system to a mathematical representation is invariably subject to compromise and open to individual interpretation. The level of detail and choice of idealisation of suspension components will depend on the application, and in the real world it also depends on the availability of information about the system. This paper discusses appropriate modelling choices for different applications, and comments on best practice for the idealisation of suspension components, wheel/rail contact conditions and modelling inputs such as track geometry. The validation of simulation results is increasingly important, and this paper discusses recent trends in this area. Finally, the paper takes a brief look forward to future simulation issues.

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