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This study assessed the effects of vehicle mileage on the floor panel geometry and the upper mounting of the McPherson struts, as well as on the wheel alignment parameters. Geometry changes were determined in cars with the same design parameters, differing only in the type of engine supply system. The cars were van-bodied vehicles with compression ignition engines fuelled with diesel fuel and spark-ignition engines fuelled with LPG. The vehicles differed significantly in the weight distribution on their axles. The study is distinguished by its comprehensive approach to identifying in-service body wear. A detailed analysis covered not only the main causes of changes in body geometry, namely the influence of the vehicles' mileage and design parameters, but also the effect of identifying the values of changes in the suspension and steering system geometry parameters. The body geometry and wheel alignment testing was carried out at a mileage of approximately 300,000 km. The study determined the relationships between changes in body geometry and wheel alignment. Changes in body geometry were determined by the type of basis point and the type of vehicle under analysis. Major changes in body geometry and wheel alignment were found in diesel-fuelled cars at the front of the vehicles and in LPG-fuelled cars at the rear of the vehicles. The greatest changes in body geometry in both vehicle types were noted within the area of the points associated with the mounting of the front and rear axle suspension system components. [ABSTRACT FROM AUTHOR]

As an important component of the running gear of high-speed trains, axle box bearings can cause lubricating grease failure and damage to bearing components under continuous high-temperature operation, which will affect the normal operation of high-speed trains. Therefore, bearing temperature is one of the key parameters to be monitored in the online monitoring system for trains. Based on the thermal network method, this paper establishes a thermal network model for the axle box bearing, considering the radial thermal deformation of the double-row tapered roller bearing components caused by the oil film characteristics and the temperature variations of the lubricating grease. A thermo-mechanical coupling model for the grease-lubricated double-row tapered roller axle box bearing of high-speed trains with track irregularity excitation is established. The correctness of the model is verified using the test bench data, and the temperature of the bearing at different rotational speeds, loads, fault sizes, and ambient temperatures are investigated. [ABSTRACT FROM AUTHOR]

This study investigates the improvement of off-road vehicle lateral stability by integrated control of active rear steering (ARS) and rear differential braking (RDB) and how the performance of such systems compares on smooth and rough roads. The ARS and RDB controllers comprise a sliding mode controller (SMC) for which critical design choices are the SMC reference model, SMC gain and integration rule. Findings include that the kinematic model reference error is preferred over the phase plane location error on both terrains, the SMC gain is terrain dependent, and the rear axle slip angle is the preferred integration rule over the stability index (SI) on both terrains. The study also found that RDB, and to a lesser degree ARS, tends to improve on the baseline vehicle path-following ability for a double lane change (DLC) manoeuvre on both terrains, but RDB has a larger loss of speed compared to ARS. The Rear axle slip angle was found to be a terrain-dependent tuneable integration rule to combine ARS and RDB, and this resulted in a control system that has the good path-following ability of RDB but the low loss of speed associated with ARS after tuning. [ABSTRACT FROM AUTHOR]

ABSTRACT The accuracy and efficiency of the wheel‐rail adhesion model are important to the wheel‐rail rolling contact issues. The purpose of this study is to develop a simplified non‐Hertzian wheel‐rail adhesion model under interfacial contaminations to predict the wheel‐rail adhesion coefficient. Firstly, a non‐Hertzian full elasto‐hydrodynamic lubrication (EHL) model was developed and applied to determine the wheel‐rail contact pressure and film thickness under interfacial contaminations. Then, the empirical formula of central film thickness available to non‐Hertzian wheel‐rail normal contact relating to train speeds, axle loads and material parameters were proposed based on a large number of non‐Hertzian full EHL simulation for smooth surface under interfacial contaminations using linear regression. The empirical non‐Hertzian central film thickness formula and minimum film thickness formula for wheel‐rail contact obtained in this paper show certain differences from the formulas based on Hertzian contact. Using the proposed non‐Hertzian central film thickness formula, a simplified non‐Hertzian wheel‐rail contact adhesion model was developed, and the adhesion coefficient was obtained at different speeds and compared with the field test data. The numerical results showed good agreement with field test data. [ABSTRACT FROM AUTHOR]

Type I main‐chain polyrotaxanes (PRs) with multiple wheels threaded onto the axle are widely employed to design slide‐ring materials. However, Type II main‐chain PRs with axles threading into the macrocycles on the polymer backbones have rarely been studied, although they feature special topological structures and dynamic characteristics. Herein, we report the design and preparation of Type II main‐chain PR‐based mechanically interlocked networks (PRMINs), based on which the relationship between microscopic motion of mechanical bonds on the PRs and macroscopic mechanical performance of materials has been revealed. The representative PRMIN‐2 exhibits a robust feature in tensile tests with high stretchability (1680 %) and toughness (47.5 MJ/m3). Moreover, it also has good puncture performance with puncture energy of 22.0 mJ. Detailed rheological measurements and coarse‐grained molecular dynamics (CGMD) simulation reveal that the embedded multiple [2]rotaxane mechanical bonds on the PR backbones of PRMINs could undergo a synergistic long‐range sliding motion under external force, with the introduction of collective dangling chains into the network. As a result, the synchronized motions of coherent PR chains can be readily activated to accommodate network deformation and efficiently dissipate energy, thereby leading to enhanced mechanical performances of PRMINs. [ABSTRACT FROM AUTHOR]

Dynamical vehicle performances depend on its center of gravity's position. It is necessary to determine this position as closely as possible. The current methods of determining the center of gravity's position are either not sufficiently accurate or are very demanding in relation to finances, time and special equipment. At the same time, there is a lack of accurate data on the center of gravity's position of current vehicles for further research. Therefore, the purpose of this study is to propose such a methodology of measuring the center of gravity's position, including its height, which is accurate enough and has as low-demand measuring equipment as possible. Another purpose of this study is to obtain data on the change in the centers of gravity's positions in different vehicles due to various load distributions. Extensive experimental measurements, according to the innovative methodology, were performed with five vehicles. The positions of the center of gravity were determined for various load distributions, and the results were analyzed in detail. [ABSTRACT FROM AUTHOR]

The results of the inspection of mechanical properties were provided for very-thick-walled shells (D/S ≈ 3.06 and D/S ≈ 3.1) made from T‑grade steel wheel manufactured by screw piercing using experimental and industrial two-high mill MISiS 130D with the feed angle β = 12°/μ = 1.26 and β = 14°/μ = 1.36. A comparison of the obtained results of mechanical properties showed that the piercing process with a larger feed angle (i.e., β = 14°/μ = 1.36) is more preferable than the piercing process with β = 12°/μ = 1.26 to improve the properties of initial hollow billets. The analysis of the dimensions of very-thick-walled shells made from steel wheel with the ratio of D/S ≈ 3.1 manufactured by piercing using the screw rolling mill MISiS 130D showed high precision, with outer diameter deviation ∆D = (−0.1 mm; +0.3 mm), inner diameter deviation ∆d = (0 mm; +0.4 mm), and wall thickness deviation ∆S = (−0.3 mm; +0.2 mm). When manufacturing hollow billets made from axle steel to manufacture hollow car axles using the industrial pipe rolling mill 70-270 (Vyksa Steel Works), we registered the positive effect of the screw piercing process (β = 12°/μ = 1.3) on strength, plastic properties, and impact strength, that is, relative elongation (δ; initial/as-pierced condition) was 38.9%/41.9 MPa and impact strength KCU+20 was 63.3/72 J/cm2. [ABSTRACT FROM AUTHOR]

This paper proposes an anti-derailment device that can be installed on the bogie to minimize the loss incurred by derailment accidents. The device is designed to create a stable four-point contact between the bogie and the rail once the wheel climbs the rail and derails, thereby preventing derailment. Full-scale derailment tests have been carried out to demonstrate the efficacy of the anti-derailment device. During the bogie test, the anti-derailment device successfully reduced the lateral acceleration at the derailed wheel axle box by 18.1%, effectively preventing wheel derailment. Since vehicle derailment tests are destructive, simulation models were used to compare the safety improvement of the anti-derailment device under derailment conditions, which showed a reduction of lateral acceleration at the derailed wheel axle box by 35.9%. Compared with the normal vehicle, the critical operation speeds of the vehicle are amplified greatly by the anti-derailment device. The results demonstrate that the anti-derailment device is a practical solution that effectively mitigates train derailment accidents caused by wheel derailment. [ABSTRACT FROM AUTHOR]

AbstractThis article proposes a trailer-axle arrangement for a long combination vehicle, i.e., a B-train double with trailer tridem-axle groups, in which the lead-axle of each group is an active trailer steering axle, and the two rear-axles are passive trailer steering axles. Given this trailer-axle arrangement, a cost-effective active trailer steering system is devised. It is assumed that in low-speed curved-path negotiations, a passive trailer steering system, e.g., self- or command-steering, will operate, while in high-speed operations, the active trailer steering system is to be activated. For the active trailer steering control, three controllers are evaluated, which are designed using the linear quadratic regulator, linear quadratic Gaussian, and µ-synthesis techniques. The performance of these designs is assessed using closed-loop simulation. The insightful findings from this study will provide guidelines for designing active trailer steering systems for long combination vehicles. [ABSTRACT FROM AUTHOR]

The vehicle dynamic load can greatly affect the service life of pavement. To study the vehicle dynamic load accurately and conveniently under different pavement characteristics and driving conditions, a multibody dynamics method was employed to establish a three-dimensional (3D) vehicle dynamics simulation model of a six-axle heavy vehicle (the most typical heavy vehicle on an expressway). Experimental tests of vehicle component parameters and axle spindle loads were performed to provide simulation parameters and to validate this vehicle dynamics model, respectively. The validation results showed that the accuracy and robustness of the dynamics model were satisfactory. Based on the validated model, the effects of International Roughness Index (IRI) and vehicle speed on the dynamic load coefficient (DLC) were explored. The DLC increased by about 80% when the speed or IRI changed from 30 km/h or 1.184 m/km to 70 km/h or 3.551 m/km , respectively. To better evaluate the effect of dynamic load, the relationship between the DLC of the vehicle and the vehicle speed and IRI is proposed according to simulation results. This relation equation can quickly and accurately study the DLC of this heavy vehicle under different IRI pavements and driving speeds. Because the vehicle dynamics model is convenient for studying the dynamic load under different conditions, this method is recommended in vehicle–pavement coupled analysis. [ABSTRACT FROM AUTHOR]

Railway infrastructure relies on the dynamic interaction between wheels and rails; thus, assessing wheel wear is a critical aspect of maintenance and safety. This paper focuses on the wheel–rail wear indicator T-gamma (Tγ). Amidst its use, it becomes apparent that Tγ, while valuable, fails to provide a comprehensive reflection of the actual material removal and actual contact format, which means that using only Tγ as a target for optimization of profiles is not ideal. In this work, three different freight wagons are evaluated: a meter-gauge and a broad-gauge heavy haul vehicles from South American railways, and a standard-gauge freight vehicle operated in Europe, with different axle loads and dissimilar new wheel/rail profiles. These vehicles are subjected to comprehensive multibody simulations on various tracks. The simulations aimed to elucidate the intricate relationship between different wear indicators: Tγ, wear index, material removal, and maximum wear depth, under diverse curves, non-compensated lateral accelerations (Anc), and speeds. Some findings showed a correlation of 0.96 between Tγ and wear depth and 0.82 between wear index and material removed for the outer wheel. From the results, the Tγ is better than the wear index to be used when analyzing wear depth while the wear index is more suited to foresee the material lost. The results also show the low influence of Anc on wear index and Tγ. By considering these factors together, the study aims to improve the understanding of wheel–rail wear by selecting the best wear analysis approaches based on the effectiveness of each parameter. [ABSTRACT FROM AUTHOR]

The bridge influence line can effectively reflect its overall structural stiffness, and it has been used in the studies of safety assessment, model updating, and the dynamic weighing of bridges. To accurately obtain the influence line of a bridge, an Empirical and Variational Mixed Modal Decomposition (E-VMD) method is used to remove the dynamic component from the vehicle-induced deflection response of a bridge, which requires the preset fundamental frequency of the structure to be used as the cutoff frequency for the intrinsic modal decomposition operation. However, the true fundamental frequency is often obtained from the picker, and the testing process requires the interruption of traffic to carry out the mode decomposition. To realize the rapid testing of the influence lines of bridges, a new method of indirectly identifying the operational modal frequency and deflection influence lines of bridge structures from the axle dynamic response is proposed as an example of cable-stayed bridge structures. Based on the energy method, an analytical solution of the first-order frequency of vertical bending is obtained for a short-tower cable-stayed bridge, which can be used as the initial base frequency to roughly measure the deflection influence line of the cable-stayed bridge. The residual difference between the deflection response and the roughly measured influence line under the excitation of the vehicle is operated by Fast Fourier Transform, from which the operational fundamental frequency identification of the bridge is realized. Using the operational fundamental frequency as the cutoff frequency and comparing the influence-line identification equations, the empirical variational mixed modal decomposition, and the Tikhonov regularization to establish a more accurate identification of the deflection influence line, the deflection influence line is finally identified. The accuracy and practicality of the proposed method are verified by real cable-stayed bridge engineering cases. The results show that the relative error between the recognized bridge fundamental frequency and the measured fundamental frequency is 0.32%, and the relative error of the recognized deflection influence line is 0.83%. The identification value of the deflection influence line has a certain precision. [ABSTRACT FROM AUTHOR]

Spatiotemporal axle temperature forecasting is crucial for real-time failure detection in locomotive control systems, significantly enhancing reliability and facilitating early maintenance. Motivated by the need for more accurate and reliable prediction models, this paper proposes a novel ensemble graph convolutional recurrent unit network. This innovative approach aims to develop a highly reliable and accurate spatiotemporal axle temperature forecasting model, thereby increasing locomotive safety and operational efficiency. The modeling structure involves three key steps: (1) the GCN module extracts and aggregates spatiotemporal temperature data and deep feature information from the raw data of different axles; (2) these features are fed into GRU and BiLSTM networks for modeling and forecasting; (3) the ICA algorithm optimizes the fusion weight coefficients to combine the forecasting results from GRU and BiLSTM, achieving superior outcomes. Comparative experiments demonstrate that the proposed model achieves RMSE values of 0.2517 °C, 0.2011 °C, and 0.2079 °C across three temperature series, respectively, indicating superior prediction accuracy and reduced errors compared to benchmark models in all experimental scenarios. The Wilcoxon signed-rank test further confirms the statistical significance of the result improvements with high confidence. [ABSTRACT FROM AUTHOR]

Multi-source fault working conditions may accelerate the deterioration of the axle box bearings on the high-speed train and worsen their dynamic performance. In the context, a coupling model including the high-speed train and axle box bearings was established. Combined with the wheel flat model and the axle box bearing fault model, the acceleration vibration response characteristics of the axle box bearing were obtained through the co-simulation under multi-source fault working conditions. The vibration properties of bearings on the same bogie were analyzed, and the stability of the bearings was further analyzed as the vehicle through a curve-line condition. According to the research, a defect on a wheel will affect all axle box bearings on the same bogie, but a fault on a bearing will not. The longitudinal and lateral directions of the vehicle's running are advantageous for detecting bearing faults. The motion instability of the bearing is increased if the wheel has a defect or the vehicle travels over the curve section. Besides, both the force on the axle box bearing and its internal contact force are significantly affected by the rail line conditions. [ABSTRACT FROM AUTHOR]

The stick–slip phenomenon, the initial stage when the traction wheel starts sliding on the rail, is a critical operation that needs to be detected quickly to control the traction drive. In this study, we have developed an experimental model that uses acceleration sensors mounted on the wheel to evaluate the amplitude of the stick–slip phenomena. These sensors can alert the driver or assist the traction control unit when a stick–slip occurs. We propose a method to reduce the amplitude of the stick–slip phenomenon using special hydraulic dampers and viscous dampers mounted on the tractive axles of the locomotive to prevent slipping during acceleration. This practical solution, validated through numerical simulation, can be readily implemented in railway systems. The paper's findings can be used to select the necessary sensors and corresponding vibration dampers. By implementing these sliding reducers, a locomotive can significantly improve traction, apply more torque to the wheel, and increase the load of a carrier train, instilling confidence in the efficiency of the proposed solution. [ABSTRACT FROM AUTHOR]

This paper shows the usage of a numerical analysis model that enables the calculation of the life of railway wheels used for low-floor freight wagons as a function of its primary operating factors, which allows for carrying out sensitivity analyses. Low-floor wagons are being increasingly used for combined transport applications, and many types of bogies have been proposed to constitute the wagons. Due to the uniqueness of this type of wagon, the bogie configurations in terms of wheelbase and axle load have hardly been analyzed so far. The numerical analysis model used addresses the primary challenges that arise in the vehicle–track interaction and establishes the relations among them. The main aspects of this model have been described in this paper, which has been later used to calculate the life of an ordinary-diameter wheel for several wheelbase and axle load values. This study has been replicated with reduced-diameter wheels, which are commonly used for low-floor wagons. In this way, it is possible to know the evolution of the life depending on the wheelbase and the axle load. The observed behaviors are not so dissimilar for the different types of wheels, and they point out huge increases in wear as the axle load and the wheelbase rise, especially with axle load. The root causes can be explained by the entire understanding of the rolling phenomenon provided by the full analytical work. [ABSTRACT FROM AUTHOR]

Rotaxanes are typically prepared using covalent bonds to trap a wheel component onto an axle molecule, and rotaxane-type wheel–axle assembly using only noncovalent interactions has been far less explored. Here we show that a dinickel(II) metallomacrocycle forms two different types of wheel–axle assemblies with a dibenzylammonium axle molecule based only on noncovalent interactions. The non-threaded assembly was obtained by introduction of Ni2+ into the macrocycle before the complexation with the axle molecule (metal-first method). The non-threaded assembly was in rapid equilibrium with each of the components in solution. The threaded assembly was obtained by introduction of Ni2+ after the formation of a pseudorotaxane from the non-metalated wheel and the axle molecule (axle-first method). The threaded assembly was not in equilibrium with the dissociated species even though it was maintained only by noncovalent interactions. Thus, formation of one of the non-threaded and threaded wheel–axle assemblies over the other is governed by the assembly pathway. Mechanically interlocked rotaxanes are typically prepared using covalent bonds to trap a wheel component onto an axle molecule, and rotaxane-type wheel–axle assembly using only noncovalent interactions has been far less explored. Here, a dinickel(II) metallomacrocycle is found to form two different types of wheel–axle assemblies, with a dibenzylammonium axle molecule forming both non-threaded and rotaxane-type threaded assemblies, based only on noncovalent interactions, with formation of one over the other governed by the assembly pathway. [ABSTRACT FROM AUTHOR]

In many countries, railway cars with axles that have operated for over 50 years are still in use, which significantly exceeds their normative service life. This can be explained by the fact that design calculations are based on overestimated loads, as evidenced by published information on diagnostics of railway axles, which is performed under real operating conditions. In this work proposes a method for calculating the durability of axles of railway cars under real operating conditions, which is based on fatigue tests of samples made of axle material, the statistical theory of similarity of fatigue failure, analysis of the stress state and known models of fatigue curves. The calculations performed showed that, under real operating conditions, the durability of the axles exceeds N=1010 cycles, which indicates their operation in the field of gigacycle fatigue. These values N correspond to a service life of over 30 years. Recommendations are given for assessing the durability of railway axles, taking into account actual operating conditions. [ABSTRACT FROM AUTHOR]

This paper presents a multibody model of the post-derailment dynamics of a railway vehicle and its impact with a derailment containment wall (DCW) built aside the line and demonstrates the use of the model in the context of the structural sizing of devices intended to mitigate derailment effects. With respect to existing multibody models of railway vehicle dynamics, the innovative features of this model are a new contact model capable to provide a plausible prediction of the derailment process despite a simple and computationally efficient formulation, and the model of the interaction between the derailed vehicle and the impacted derailment containment structure, the latter being described by a Finite Element Model. Results from the model are compared to an established multibody software for a non-derailment case, and then a comparison is performed with a measurement from a derailment experiment published in the scientific literature, finding in both cases satisfactory agreement. The model is then applied to analyse a derailment scenario caused by the sudden failure of an axle for a locomotive vehicle travelling at 300 km/h in a HS curve, deriving the peak values of the impact force and bending moment at the base of the derailment containment wall. [ABSTRACT FROM AUTHOR]

The manuscript presents a new manufacturing technology for the production of hollow railway axle forgings. The manufacturing technology analyzed is based on three-roll skew rolling (TRSR) using a computer numerically controlled (CNC) rolling mill. The study focused on comparing the rolling capability of hollow products without and with a mandrel calibrating the hole of the forging. The influence of tube billet size on the rolling process was also analyzed. FE analysis and experimental studies were carried out. An analysis of the accuracy of the internal hole of the forging depending on the adopted parameters of the rolling process was carried out. Based on numerical simulations, the state of strain and the flow pattern of the material and temperature distribution during rolling were determined. The force parameters of the rolling process of hollow forgings were also analyzed. Based on the research, a two-stage rolling technology for rolling hollow railway axle forgings was proposed. The results obtained indicate the suitability of using a calibrating mandrel to improve hole accuracy in hollow forgings rolled from a tubular billet. The gap c between the bore diameter of the forging and the diameter of the mandrel was measured. Increasing the tubular billet dimensions from Ø42.4 × 10 mm to Ø48.3 × 12.5 mm reduced the gap c by 49.8%. Rolling the billet Ø51 × 14.2 mm in two passes compared to rolling in one pass reduced the gap c by 45.5%. [ABSTRACT FROM AUTHOR]

One fine spring morning, at some point, I was simply tearing a few sheets of paper towel off a fresh roll. As the sheets came off and the roll rotated about the vertical axle of the holder (Figure 1), I lazily pondered the geometry lurking in the situation. I realised that sometimes I would let the roll rotate as the unwound part moved straight until tearing, while at other times, I might hold the roll in place and unwind the sheets around the roll. More often, it would be some spontaneous combination of the two modes of unwinding. [ABSTRACT FROM AUTHOR]

High-speed railway S38C axles undergo surface induction hardening for durability, but are susceptible to fatigue cracks from foreign object impact. The neutron diffraction method was employed to measure the residual strain in S38C axles, obtaining microscopic lattice distortion data, for the gradient layer at a depth of 8 mm under the surface. The results showed that after induction-hardening, the microscopic lattice distortion had a gradient distribution, decreasing with the distance from the surface. However, in the case of impacting speed of 600 km/m, the average microscopic lattice distortion increased with the distance from the surface, reaching a maximum augmentation of 55 pct. These findings indicate a strong experimental basis, and improve our understanding of the relationship between macroscopic residual stress and decision-making, in regard to operation and maintenance. [ABSTRACT FROM AUTHOR]

Car trailers are quite a popular means of transport and are offered in many versions, from single axle light trailers with a maximum permissible weight of 750 kg, through two- or more-axle specialized trailers. The issues of research car trailers focus on two directions: testing the driving properties and analysing the strength of the supporting frame system. Issues related to the construction of light trailers are often common to trailers used in agriculture or general transport. In this article, based on a mass-produced car trailer, an analysis was carried out regarding the choice in the technology of making the supporting structure consisting of a lower frame and an upper frame. The term upper frame should be understood as the structure on which the lifted load box rests. The costs of materials, assembly and technological possibilities of small-scale production were taken into account. In addition, strength analyses of the numerical models were carried out for critical areas of the frame during operation. After considering the unit costs for each of the analysed assembly technologies, it was shown that riveting would be the cheapest. However, the most suitable method of assembly is welding, as it allows the use of standard profiles. [ABSTRACT FROM AUTHOR]

This paper deals with a surface-hardened forged steel that is commonly used for powertrain components like gears, axles or crankshafts. In order to increase static and fatigue strength and to minimise wear, surface treatments like induction hardening lead to a significant microstructural change within heat-affected zones. The aim of this study was to elaborate a method for a reliable computational estimation of the local fatigue strength by considering local material properties. The method is based on experimental test results, where specimens were extracted from forged crankshafts and further heat-treated to investigate the fatigue strength of the unhardened and hardened material condition. The experimental test data were fundamental in defining elaborated Haigh diagrams, enabling a more reliable local fatigue assessment. The comparison of the component safety within the fatigue strength verification for a crankshaft section under alternate bending resulted in 28 % -more progressive dimensioning of surface hardened layers. [ABSTRACT FROM AUTHOR]

AbstractThis work describes the elastokinematic design and optimization for a new, package space saving rear suspension especially intended for small battery electric vehicles. Mainly for reasons of cost and weight efficiency, the twist-beam axle is widely used, especially in the A and B segments. One of the main disadvantages of twist-beam axles is that they limit the rear package space because of the torsion profile. The basic idea of this work was to reverse the installation direction of the twist-beam axle to create an additional package space for the battery. To obtain an optimized elastokinematic design, a new algorithm was introduced that allows modeling of the elastokinematic behavior of the new mechanism. A Pareto optimization of the body connecting bushing was performed, revealing that a specific spatial orientation enables effective compensation for camber compliance deficits. Finally, the Pareto-optimized elastokinematic design was compared to compliance measurement results of a prototype vehicle equipped with the new suspension concept. [ABSTRACT FROM AUTHOR]

AbstractShimmy is a self-accident lateral and yaw vibration of a wheel caused by the interaction between the dynamic behavior of the tire and the supporting structure. The shimmy affects road vehicles, motorcycles, and aircraft landing gears. This undesired vibration can increase to a considerable amplitude, producing loss of control and may even result in severe damage to the wheel-suspension system. Suitable tools and models are required to assess the system’s stability properties and understand shimmy mechanisms. This research focuses on the technical solutions to reduce the shimmy phenomenon. The suspension, axle, and bearing part on the axle work together in a united way to protect against the forces transmitted by the wheels’ imbalances. This physical phenomenon suggests balancing the wheel by considering a mechanical system consisting of suspensions, axles, and wheels. In the design phase, the research suggests balancing the axle and wheels, comparing two planes, and influencing coefficient methods. An inertial measurement unit (IMU) sensor can capture mechanical vibrations on the wheel at various vehicle speeds. [ABSTRACT FROM AUTHOR]

Vibrations in road vehicles cause several harmful effects, health problems can occur for the passengers, and mechanical damage can occur to the vehicle components. Given the health, safety, and financial issues that arise, keeping the road network in good condition and detecting road defects as early as possible requires an extensive monitoring system. Related to this, our study presents the development of hardware and software for a low-cost, multi-sensor road quality monitoring system for passenger vehicles. The developed monitoring system can classify road sections according to their quality parameters into four classes. In order to detect vibrations in the vehicle, accelerometers and gyroscope sensors are installed at several points. Then, a machine learning-based soft-sensor development is introduced. Besides noise filtering, each data point is resampled by spatial frequency to reduce the velocity dependence. Subsequently, a decision tree-based classification model is trained using features from the power spectrum and principal component analysis. The classification algorithm is validated and tested with measurement data in a real-world environment. In addition to reviewing the accuracy of the model, we examine the correlation of the data measured in the cabin and on the suspension to see how much additional information is provided by the sensor on the axle. [ABSTRACT FROM AUTHOR]

Four-wheel steering (4WS) is an effective technique to improve handling performance and lateral stability of road vehicles. Conventionally, controllers utilise the driver's actions and vehicle dynamics to coordinate front and rear-axle steering. This paper proposes a novel approach for 4WS controller design, based on the concept of Artificial Flow Guidance (AFG), which relies on a spatially distributed motion reference through a two-dimensional vector field. This field provides high-level guidance while lower-level steering controllers to control axle centres motions relative to the flow. These flow vectors, computed in real-time via simple geometric construction, can be pre-computed globally to evaluate the guidance algorithm's efficacy. When controlling only the front axle, this same approach can function as an autonomous driving system. Relying solely on a spatial reference field and control targets' velocities enables the controller to work in a simple and robust fashion, without using a reference vehicle dynamics model or lengthy parameter tuning. The proposed approach's effectiveness is validated through co-simulation with MATLAB/Simulink and the CarMaker simulation platform. AFG control performance is found to be at least comparable to that of more complex 4WS controllers using methods such as MPC; in the cases considered, AFG provides superior path-tracking performance. [ABSTRACT FROM AUTHOR]

The axle box bearing serves as a critical rotational component for high-speed trains. Thus, it is of great significance to obtain accurate loading conditions for axle box bearings for its reliability design. In this study, a bearing-vehicle coupled system dynamic model, consisting of an equivalent bearing model characterized by the time-varying stiffness in the bearing, a nonlinear high-speed train dynamic model, and a slab track model, is developed. The validity of the proposed coupled dynamic model is demonstrated by comparing the simulated results with those obtained in a field test and the literature, respectively. Subsequently, the influence of long- and short-wavelength irregularities on the dynamic responses of bearings is investigated using the proposed coupled model in terms of dynamic loads of the axle box bearing. The results obtained by the proposed model are further compared with those calculated using a traditional vehicle dynamic model that represents the bearing as a revolute joint, so as to illustrate the advantages of the proposed model. The results suggest that the loading responses of the bearing calculated by the two models exhibit differences, which are simultaneously related to the structural damping of the bearing and the mode frequency change of the system. [ABSTRACT FROM AUTHOR]

Traffic load is one of the important external loads of bridges and simulating the site-specific traffic load is important for bridge condition assessment. This study proposes a new microscopic model to simulate the stochastic traffic load of any time period at bridge site based on weigh in motion (WIM) data. A model for simulating the microscopic interaction between vehicles was first proposed, by which free driving, car following and sudden braking can be reasonably simulated. Axle-weight information from the WIM data was embedded into the model to precisely simulate the vehicle load. A new vehicle sequence generation method based on WIM data was then proposed to generate the site-specific vehicle sequence of any time period with consideration of non-stationarity. Finally, a framework for simulating the site-specific stochastic traffic load is established. The proposed framework is validated through application based on realistic WIM data in traffic-flow simulation and load effect quantification. Comparisons of simulation results with the existing methods were also conducted to show the reasonability and novelty. The results indicate that the proposed framework can produce reasonable site-specific stochastic traffic load over any time period based on WIM data. [ABSTRACT FROM AUTHOR]

As a step toward revolutionizing and optimizing freight transport, autonomous truck platooning technology (i.e., a set of connected heavy-duty trucks traveling closely at specific headway intervals) has been the center of research over last few years. Connected autonomous vehicles (CAV), in the form of truck platooning, can be implemented as a novel contribution to sustainable freight transport with the potential of offering the following synergistic benefits, among others: road safety improvements, enhanced economic prospects, and environmental preservation. In this study, the impacts of fixed-path truck platooning on pavement performance were modeled and numerically quantified using elastic and dynamic-viscoelastic finite-element (FE) methods. Factors including pavement layers' geometrical and mechanical characteristics, traffic characteristics and counts, axle configuration, and seasonal temperature are analyzed to address the platooning effect in this study. Yet, other possible wandering patterns between the fixed-path and normally distributed wandering patterns, as well as the effects of speed variations, driving behaviors, and tire pressure (i.e., variation in dynamic loading), can be further studied. The mechanical responses (namely displacements, strains, and stresses) obtained from the FE modeling were used to predict the effects of truck platooning on the pavement performance due to limited wandering (lateral movement of truck tires). The FE modeling results indicated that the channeling effects (i.e., limited tire wandering) of truck platooning have negative effects on the pavement performance with respect to decay in fatigue life and increase in permanent deformation. With fixed-path platooning, the fatigue life is reduced in the range of 13.9% to 34.5% in terms of the number of load cycles over the 20-year design life. The permanent deformation (rutting) value over a fixed period is increased by a factor of 1.2 to 2.9. [ABSTRACT FROM AUTHOR]

This investigation examines the influence of braking on the reliability of bituminous pavements. For this purpose, different loading conditions of a two-axle truck are simulated using vehicle dynamics software. Individual response surface methodology models to predict critical strain values are developed for various thickness and modulus values and loading combinations. Monte Carlo simulations are then used to generate random variabilities of input parameters, and the reliability is estimated accordingly. Three different cases are simulated. In the first case, it is assumed that all the vehicles impact the pavement by braking, and the reduced reliability is found to vary between 99.8% and 1.2% for the different loading and braking conditions. In the second case, the allowable load repetitions for fatigue damage are computed for a given reliability of 90% and are found to vary between 24 and 1 million standard axle (MSA). In the third case, different combinations of braking conditions are investigated, and the reliability is estimated. [ABSTRACT FROM AUTHOR]

In Japan, small agricultural tractors without axle suspensions used on bumpy farm roads experience severe vibrations. Excessive vibrations often cause tyres to lose contact with the supporting ground or decrease the vertical tyre force such that the cornering force exceeds the static friction limit. The resulting bouncing and sliding motions induce steering instability, resulting in overturning accidents. This study investigated the effectiveness of axle suspension in alleviating bump disturbance-induced steering instability in small tractors. A step lane change test involving bump disturbances was newly proposed for the steering stability testing of small tractors. The numerical experiments compared four axle suspension structures: no-, front-, rear-, and full-suspensions. The results showed that bump disturbances induce steering instability in the no- and rear-suspension tractors. In contrast, the front- and full-suspension structures significantly improved the steering stability of the tractor by keeping the steering wheel in contact with the ground. The proposed testing method helped evaluate improvements in the steering stability brought about by increasing the ground contact of the steering wheel. Our results can aid in designing and testing suspension systems for small tractors. • Tractor bouncing, sliding, and driver models were newly coupled for simulations. • Step lane change involving bump disturbances was proposed for stability test. • Steering instability was found in the no- and rear-suspension tractors. • Front- and full-suspensions could significantly alleviate steering instability. [ABSTRACT FROM AUTHOR]

This paper deals with the phenomenon of torsion oscillations in railway vehicle drive systems. The main goal is to reduce the risk of presence of torsional oscillations in wheelset drive, eventually to propose systems to effectively identify and eliminate torsional oscillations of wheelsets. Therefore, a simulation wheelset drive model including a detailed model of the asynchronous traction motor control was built. The results of computer simulations show that the torsional oscillations can be effectively eliminated by avoiding the resonance states between the excitation frequencies given by pulse width modulation of the inverter and the eigenfrequencies of the mechanical part of the drive. Furthermore, it was found that the presence of torsional oscillations of the wheels can be detected based on the traction motor current ripple. The wheelset drive model was subsequently implemented in a simulation model of a four-axle locomotive. A new algorithm of an anti-slip protection system that utilizes motor currents was implemented in the model. Simulations show that such an anti-slip protection system can prevent the occurrence of undesired large amplitude of wheelset torsional oscillations. The models and simulation results are presented in detail in the paper. [ABSTRACT FROM AUTHOR]

For calibrating the measurement error of the speed sensor and estimating the speed accurately while system is nonlinear and noise is non-Gaussian, dual radar and wheel axle sensor are configured and federal particle filter is used to acquire fusion. The whole operation process of CRH3 train from start to stop between two stations is taken as an example, the speed measurement errors of different speed estimation methods under the conditions of train idling, slipping, vibration and the speed sensor with dynamic noise are analyzed and verified. The simulation results show that: The root-mean-square error can be reduced by 31.52% and 47.35% respectively in the idling and sliding stages after the calibration of dual-radar and wheel-axle combination compared with no calibration; Compared with the two types of dual-radar calibration methods, the maximum relative error of the dual-radar separation vibration speed calibration method can be 39.66% lower than that of the dual-radar angle deviation estimation calibration method when the train vibration speed ratio is 0 to 1 and the radar installation angle error is -1° to 1°. Compared with the filtering results of dual radar and axle sensors before fusion, the speed measurement results after using joint particle filtering fusion are 34.71% and 14.03% lower in MAE, and 26.51% and 10.98% lower in RMSE respectively. Compared with federated extended Kalman filter fusion, the root mean square error of velocity measurement using federated particle filter fusion is 26.97% lower and the maximum absolute error can be reduced by 16.10%. [ABSTRACT FROM AUTHOR]

Weigh-in-motion (WIM) technology provides accurate information about road network traffic, including vehicle class and speed, vehicle count, gross vehicle weight (GVW), wheel and axle weights, axle spacing, date, and time of each vehicle passage over WIM sensors. Several factors can affect the WIM system accuracy (i.e., measurement error). The potential site-related influences include road geometry, pavement stiffness, surface distresses, roughness, and climate. Further, the WIM calibration and equipment-related factors also have a substantial effect, including sensor type and array, calibration speed, and speed points used by the WIM controller. The long-term pavement performance (LTPP) database was used to study the relative importance of these factors. The WIM calibration data were available for bending plate (BP), load cell (LC), quartz piezo (QP), and polymer piezo cable (PC) sensors. The representative values of GVW measurement errors were estimated using WIM equipment calibration data for all sensors. The BP sensor showed the lowest errors, followed by LC and QP sensors. The PC sensor indicated the highest WIM measurement errors among all sensor types. Decision tree models developed in this paper illustrate a potential for estimating the expected WIM measurement error range using information about the WIM site and sensor-related factors. The results show that the sensor array and types are the most important predictors, followed by WIM controller functionality (speed points). The data analysis and results also show that for some sensor types, the climate is important. One can integrate this information with equipment installation and life cycle costs to determine the most reliable and economical equipment while also considering WIM data accuracy requirements by WIM data users. [ABSTRACT FROM AUTHOR]

The positive effects of deep rolling on fatigue strength—reduced surface roughness, work hardening and compressive residual stress—in the near-surface region are achieved by controlled high plasticisation of the treated material. However, excessive and/or repeated plasticising poses a risk of damage to the machined component. This paper investigates the damage caused by deep rolling of a railway axle. Two sections of the axle are experimentally deep rolled repeatedly at different feed rates until damage is detected. For comparative analysis, these experiments are numerically analysed and the damage is assessed using the strain-based damage calculation. The results are compared and a damage sum of ~120% is evaluated for both tests, thus developing a reliable and conservative assessment method. The single deep rolling treatment at a feed rate of 0.25 mm causes damage of 6.1%, and at a feed rate of 0.5 mm, damage of 4.7%. The developed and experimentally validated evaluation method allows for investigating the limits of applicability of different deep rolling parameters. The influence of the deep rolling force and feed rate and a proposed optimisation with multiple deep rolling with reduced deep rolling forces are investigated. [ABSTRACT FROM AUTHOR]

This paper considers an integrated control method combining autonomous driving and active steering. By using artificial flow guidance (AFG), the steering at all five axles on a tractor-semitrailer are synchronized for precise low-speed path tracking and improved lateral stability. AFG is a motion planning method which uses velocity vectors to guide the motion of the vehicle; here, two modification on AFG are proposed to form the integrated-AFG which improves the transient performance and generalizes the choice of the tracking points. Simulations rendered in TruckMaker show submillimeter level steady-state off-tracking for a broad speed range, with maximum deviation being 1 cm for a high-speed lane change; amplification of trailer lateral motion is also suppressed, with rearward amplification (RWA) < 1 maintained throughout. This control method is robust to changes in key parameters such as trailer mass and road friction coefficient. The methods presented provide a new foundation for implementing automated freight transportation on highways. [ABSTRACT FROM AUTHOR]

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The mechatronic vehicle developed within the Shift2Rail projects Run2Rail, Pivot, NEXTGEAR, and Pivot2 is evaluated with respect to wheel wear. The KTH wear model is used to determine the coefficients of Archard's wear map to reproduce measured worn wheel profiles of the present vehicle running on Metro Madrid line 10. The same wear model is then used to evaluate the performance of the mechatronic vehicle controlled with two variants of a feedforward controller. The first one uses on-board measurements, while the second one is optimised using firefly optimisation algorithms assuming knowledge of the travelled track. The control strategy based on on-board measurements shows improvements above 60% in terms of lost wheel volume due to wear, compared to the standard bogie vehicle. The optimised controller reaches improvements above 70%. Good coherence is found between improvements predicted with the wear number and the ones achieved in terms of lost wheel volume. [ABSTRACT FROM AUTHOR]

To improve the handling and directional stability of three-axle heavy vehicles, this paper suggests a control strategy that combines direct yaw moment control (DYC) and active front steering (AFS). The control system's structure is divided into three main layers. Based on an online adjustable index, a fuzzy controller acting as a supervised system decides the cooperation of DYC and AFS in the upper layer. In the intermediate layer, the DYC system controller uses a sliding mode controller to calculate the corrective body moment. The AFS system uses a fuzzy controller to generate the corrective steering angle necessary to achieve the three-axle vehicle motion objective. The algorithm for distributing braking force and the slip ratio control (SRC) system comprises the lower layer. The anti-lock braking system (ABS) in the SRC system is built to produce the necessary braking forces at low slip ratios while preventing the wheels from locking up at high slip ratios. Consideration has been given to a heavy, three-axle, 9-DOF nonlinear vehicle with uncertain dynamics. Trucksim software and simulation tests have validated the model. The proposed control system's satisfactory performance is shown through various maneuvers. [ABSTRACT FROM AUTHOR]

To explore and predict the fatigue performance of three-roll skew rolling (TRSR) hollow axle, a combination of experimental and numerical simulation methods was used to carry out research. First, the heat treatment of TRSR hollow axle was carried out, and the metallographic test and tensile test were carried out on its specimens. Second, the rotating bending fatigue test was carried out on the specimen, and the S–N curve was obtained by data processing. Third, combined with ABAQUS and FE-SAFE, a fatigue life prediction model was created to predict the specimen life. Fourth, the fracture analysis of the specimen was carried out to determine the fracture reason. The results show that the fatigue performance of TRSR hollow axle is better than most of the hollow axle on the market, and the fatigue life prediction model can reasonably predict the fatigue life of the specimen. [ABSTRACT FROM AUTHOR]

It is crucial to evaluate the consistency in weigh-in-motion (WIM) loading over time and quantify the relative accuracy of axle loads based on axle load spectra (ALS) data for different sensor types. This paper presents the temporal evaluation of the ALS from 51 WIM sites and 128 records available in the long-term pavement performance data. Analysis of ALS data over time shows that for single ALS, there is a significant difference in peak loads between the bending plate, and quartz piezo sensor measurements. Also, 100% of the bending plate 86% of the quartz piezo, and 66% of the piezo cables sites exhibited consistent single axle peak loads after 1 year of calibration event. For tandem ALS, significant differences were observed between loaded peaks of bending plate sensor from both quartz piezo and piezo cable sensors. Also, 83% of the bending plate, 78% of the quartz piezo, and 50% of the piezo cable sites exhibited loaded peaks consistently 1 year after calibration. The results show that calibration frequencies longer than 1 year may be acceptable for the bending plate sensors. However, calibration frequencies of at least 1 year for quartz piezo and less than a year for piezo cable sensors are recommended. Pavement designers and analysts should be aware of the changes in WIM data and calibration frequency over time. [ABSTRACT FROM AUTHOR]

The road agencies collect and submit weigh-in-motion (WIM) data to the Federal Highway Administration as part of their traffic monitoring program. Therefore, the WIM data should be precise and accurate. One way to evaluate WIM measurement errors is by using the test truck data collected immediately before and after equipment calibration. The limitation of this approach is that the data represent a snapshot in time and may not represent a long-term WIM site performance. This paper presents an approach for estimating WIM system accuracy based on axle load spectra attributes (normalized axle load spectra (NALS) shape factors). This alternative approach allows for characterizing temporal changes in WIM data consistency. The WIM error data collected before and after calibration were related to Class 9 NALS shape factors in the proposed methodology. This paper aims to determine WIM system errors based on axle loading without physically performing WIM equipment performance validation using test trucks. The presented methodology can be used to estimate systematic errors (drift) in the WIM system at any point in time after the equipment calibration. This approach can help highway agencies select optimum timings for routine maintenance and calibration of WIM equipment without compromising its accuracy. The results show that the WIM accuracy for the single axle (SA) and tandem axle (TA) can be estimated with SA and TA NALS shape factors with an acceptable degree of error for bending plate to quartz piezo sensors. Examples are included to demonstrate the application and significance of the developed models. [ABSTRACT FROM AUTHOR]

The comparative assessments and an overview of mechanical, chemical, and physical properties of rail axles are presented. This review focused on the effects of compositions and microstructure on fatigue, fretting and corrosion fatigue of rail axles. The two main steel grades: low carbon steels for commuter trains and high strength low alloy steels for high-speed trains have ferrite-pearlite microstructures with 20–40 µm ferrite grain sizes. Minimum allowable yield and ultimate tensile strengths are 330 MPa and 600 MPa, and the minimum longitudinal and transverse toughnesses are 35 J and 22 J. Most axle failures are associated with surface and sub-surface defects with micro-cracks nucleating from ballast (small-sized pebbles in rail tracks), minute oscillatory movement leading to fretting, microstructural inclusions, and corrosion pits. The implications for structural integrity are highlighted and areas for future research directions are highlighted. [ABSTRACT FROM AUTHOR]