Axle Forces Research Articles

Influence of Tire Parameters on Contact Patch and Axle Force Generation against Short Obstacles Using DOE Approach

Influence of Tire Parameters on Contact Patch and Axle Force Generation against Short Obstacles Using DOE Approach

Incorporating measurement data to improve the fatigue assessment of steel bridges

AbstractFatigue calculations of steel bridges are particularly vulnerable to inaccuracies in stress assessment. Their accurate evaluation ensures structural safety and can contribute to extending the remaining service life of many structures. The following study deals with the incorporation of measured data into fatigue assessment based on FE calculations using the trains operating on site. The bridge under study was equipped with a large number of strain gauges to capture the global and local effects of train passages. In addition, some strain gauges were placed on both rails to determine train speeds and axle forces. A detailed finite element model of the bridge was created and the strains caused by selected detected trains were blindly compared with measured values. Although a fairly good agreement was obtained for most strain gauges without the need for model updating, some sensors did not comply with the measured values. In order to achieve better agreement, a model update was performed. The authors concluded with a comparison of the original and updated models and the determined operating trains with regard to the fatigue calculations and discussed the added value.

Optimal design of variable suspension parameters for variable-gauge trains based on the improved CRITIC method

ABSTRACT The gauge differences of international rail lines have led to the emergence of variable-gauge trains. High-speed variable-gauge trains operating on different lines should meet the dynamic requirements. In order to achieve the above purpose and obtain better dynamic performance, a parameter optimization method for variable suspension systems is proposed. The SIMPACK dynamic model of high-speed variable-gauge trains is established. Six key parameters of the suspension system are chosen, and different suspension parameters are combined using the optimal Latin hypercube. Seven dynamic indices of the vehicle running on three different gauge tracks are solved separately. Weighted SNR is used to perform the multi-objective optimization. The improved CRITIC method is used to solve for the weight coefficients of each index, and find the optimal values of the key suspension parameters. The objective of adjusting the variable suspension parameters of variable-gauge trains is presented. Results from simulation show that the optimized suspension parameters can improve the dynamic performance of the variable-gauge vehicle, especially the derailment coefficient, the wheel load reduction rate, and the axle lateral force. The vehicle can operate with better dynamic performance on both gauge lines by using the designed variable suspension parameters.

A method for defining high speed train loads in time - domain FEM models

This paper presents a method for defining high speed train loads in finite element models to simulate train-induced ground vibrations in time-domain. The method assumes that wheel/rail contact is perfect and that the wheel loads act on the rails as moving forces. These moving forces are then transferred to the ballast surface as a series of equivalent concentrated forces that appear successively depending on the train speed. To verify the presented method, we compare numerical and analytical solution for a case of a track resting on an elastic half space subjected to an axle force moving at a high speed.

Integrated Vehicle–Tire–Pavement Approach for Determining Pavement Structure–Induced Rolling Resistance under Dynamic Loading

Pavement-related rolling resistances, caused by pavement–vehicle interaction, are important components of pavement life-cycle assessment (LCA). Structure-induced rolling resistance (SRR) is caused by dissipated vehicle kinetic energy in the pavement structure. This paper presents an integrated vehicle–tire–pavement approach to evaluate asphalt pavement SRR under dynamic loading. A three-dimensional (3D) semitrailer-truck model was used to calculate dynamic wheel loads on various pavement surface-roughness profiles. The dynamic wheel loads were then transformed into 3D tire–pavement contact stresses using a deep-learning tire model. Next, an advanced 3D finite element pavement model, validated in previous studies, was used to simulate pavement structure under moving tire–pavement contact stresses. The dynamic load coefficient of axle forces was found to increase linearly with truck speed. The increasing trend became more significant as pavement roughness increased. Ignoring the dynamic loading effect resulted in 12% error in predicting SRR. A case study was performed to illustrate the computation procedures of asphalt pavement SRR under static and dynamic loading. Dynamic loading accounted for 4.74%, 7.37%, 10.73%, and 14.02% of SRR for four pavement surface-roughness levels at a truck speed of 40 mph. In addition, SRR was found to be highly nonlinear and increased as speed decreased and axle load increased. A modified Illinois Center for Transportation SRR model was developed to quickly assess the SRR component of the pavement LCA’s use stage. This study demonstrates the importance of vehicle–tire–pavement interaction in SRR prediction, which may not be overlooked.

Safety evaluation of a vehicle\u2013bridge interaction system using the pseudo-excitation method

A method for analysing the vehicle–bridge interaction system with enhanced objectivity is proposed in the paper, which considers the time-variant and random characteristics and allows finding the power spectral densities (PSDs) of the system responses directly from the PSD of track irregularity. The pseudo-excitation method is adopted in the proposed framework, where the vehicle is modelled as a rigid body and the bridge is modelled using the finite element method. The vertical and lateral wheel–rail pseudo-excitations are established assuming the wheel and rail have the same displacement and using the simplified Kalker creep theory, respectively. The power spectrum function of vehicle and bridge responses is calculated by history integral. Based on the dynamic responses from the deterministic and random analyses of the interaction system, and the probability density functions for three safety factors (derailment coefficient, wheel unloading rate, and lateral wheel axle force) are obtained, and the probabilities of the safety factors exceeding the given limits are calculated. The proposed method is validated by Monte Carlo simulations using a case study of a high-speed train running over a bridge with five simply supported spans and four piers.

On the model-based design of front-to-total anti-roll moment distribution controllers for yaw rate tracking

In passenger cars active suspensions have been traditionally used to enhance comfort through body control, and handling through the reduction of the tyre load variations induced by road irregularities. However, active suspensions can also be designed to track a desired yaw rate profile through the control of the anti-roll moment distribution between the front and rear axles. The effect of the anti-roll moment distribution relates to the nonlinearity of tyre behaviour, which is difficult to capture in the linearised vehicle models normally used for control design. Hence, the tuning of anti-roll moment distribution controllers is usually based on heuristics. This paper includes an analysis of the effect of the lateral load transfer on the lateral axle force and cornering stiffness. A linearised axle force formulation is presented, and compared with a formulation from the literature, based on a quadratic relationship between cornering stiffness and load transfer. Multiple linearised vehicle models for control design are assessed in the frequency domain, and the respective controllers are tuned through optimisation routines. Simulation results from a nonlinear vehicle model are discussed to analyse the performance of the controllers, and show the importance of employing accurate models of the lateral load transfer effect during control design.

Influence of braking on dynamic stability of car-trailer combinations

The influence of braking on dynamic stability of a car-trailer combination (CTC) is studied in this paper. The braking is simply modeled and integrated into a single-track model (STM) with a single-axle trailer. On this basis, some fundamentals and analysis results related to system dynamic stability are given through simulation. Furthermore, it is found that the axle load transfer and braking force distribution have a great influence on system dynamic stability. In order to further analyze the influence of these two factors, both of the braking force distribution and the pitch motion are considered in the modeling. Finally, the ideal braking force distribution domain is proposed. Results can be adopted to explain the experimental phenomenon and serve as a guideline for the differential braking strategy in stability control of the CTC.

Reduction of Body Boom by Optimizing the Dynamic Axle Forces

Reduction of Body Boom by Optimizing the Dynamic Axle Forces

On the Design of Yaw Rate Control via Variable Front-to-Total Anti-Roll Moment Distribution

In vehicle dynamics, yaw rate control is used to improve the cornering response in steady-state and transient conditions. This can be achieved through an appropriate anti-roll moment distribution between the front and rear axles of a vehicle with controllable suspension actuators. Such control action alters the load transfer distribution, which in turn provokes a lateral tire force variation. With respect to the extensive set of papers from the literature discussing yaw rate tracking through active suspension control, this study presents: i) A detailed analysis of the effect of the load transfer on the lateral axle force and cornering stiffness; ii) A novel linearized single-track vehicle model formulation for control system design, based on the results in i); and iii) An optimization-based routine for the design of the non-linear feedforward contribution of the control action. The resulting feedforward-feedback controller is assessed through: a) Simulations with an experimentally validated model of a vehicle with active anti-roll bars (case study 1); and b) Experimental tests on a vehicle prototype with an active suspension system (case study 2).

Virtual sensor for real-time estimation of the vehicle sideslip angle

Purpose The vehicle sideslip angle is an important state of vehicle lateral dynamics and its knowledge is crucial for the successful implementation of advanced driver-assistance systems. Measuring the vehicle sideslip angle on a production vehicle is challenging because of the exorbitant price of a physical sensor. This paper aims to present a novel framework for virtually sensing/estimating the vehicle sideslip angle. The desired level of accuracy for the estimator is to be within +/− 0.2 degree of the actual sideslip angle of the vehicle. This will make the precision of the proposed estimator at par with expensive commercially available sensors used for physically measuring the vehicle sideslip angle. Design/methodology/approach The proposed estimator uses an adaptive tire model in conjunction with a model-based observer. The performance of the estimator is evaluated through experimental tests on a rear-wheel drive vehicle. Findings Detailed experimental results show that the developed system can reliably estimate the vehicle sideslip angle during both steady state and transient maneuvers, within the desired accuracy levels. Originality/value This paper presents a novel framework for vehicle sideslip angle estimation. The presented framework combines an adaptive tire model, an unscented Kalman filter-based axle force observer and data from tire mounted sensors. Tire model adaptation is achieved by making extensions to the magic formula, by accounting for variations in the tire inflation pressure, load, tread-depth and temperature. Predictions with the adapted tire model were validated by running experiments on the Flat-Trac® machine. The benefits of using an adaptive tire model for sideslip angle estimation are demonstrated through experimental tests. The performance of the observer is satisfactory, in both transient and steady state maneuvers. Future work will focus on measuring tire slip angle and road friction information using tire mounted sensors and using that information to further enhance the robustness of the vehicle sideslip angle observer.

Preliminary Discussion on Monitoring of Steel Support Axis Force in Metro Engineering

Axial force monitoring of steel support is one of the important factors for foundation pit safety monitoring. In the monitoring of steel support, there are many problems, such as unreasonable installation of axonometer, irregular monitoring behavior of axonometer, incomplete analysis of axial force and imperfect early warning system. Collecting many engineering cases, and in-depth analysis and research on the problems and irregular behavior of steel support axial force monitoring in every link. The influencing factors and control measures of steel support axial force are discussed in detail, and some useful conclusions are obtained. It has been applied in the actual monitoring work and achieved good results. It is of great significance to guide subway safety construction and promote the development of axle force monitoring industry.

3D DYNAMIC TIME-HISTORY RESPONSE ANALYSIS OF AN ISLAND PLATFORM METRO STATION IN LOESS AREA


 
 
 Through the years, the seismic resistance of underground structures has attracted more and more attention, and dynamic characteristics of metro station is one of the most important issues. In this article, the 3D numerical model of Zhang Wangqu metro station along Metro Line 5 in Xi'an is established to study on seismic dynamic response of roof, floor, columns and beams in the island platform metro station. Compared with the earthquake damage of Dakai metro station in the Kobe M7.2 Earthquake and the shaking table test of metro station in loess area, results reveal that horizontal acceleration can reflect seismic wave characteristics under the horizontal seismic wave; the maximum relative displacement of roof and floor, the maximum axle force and shear force at transfer node are bigger than the standard section and reduce with the increase of buried depth; the maximum axle force and shear force of columns increases from top to bottom. The island platform metro station should focus on the structural settings of transfer node, and the columns and beams here must select materials with greater strength.
 
 

DYNAMIC IMPACT OF HEAVY LONG VEHICLES WITH EQUALLY SPACED AXLES ON SHORT-SPAN HIGHWAY BRIDGES

Extremely large trucks with a weight exceeding the standard require a permit before they are allowed to cross the bridges of a specific route. For the purpose of safety, an escort is often employed to maintain a distance between vehicles and to ensure that the bridge load remain below the allowed maximum. Given that the speed of these large vehicles is quite slow and that the amplitude of vibrations normally declines when the vehicle mass is large, a minor dynamic amplification of the bridge response is expected. However, some of these large trucks have a unique feature characterized by “multiple equally-spaced axles”, something that is uncommon in normal vehicle. The application of axle forces at equal intervals can dynamically excite bridges to a considerable extent, even at low speeds. These “critical” low speeds are estimated a priori from the axle spacing of the truck and the main frequency of vibration of the bridge. This paper demonstrates that when the “critical” speed is unavoidable, a relatively high dynamic allowance must be added to static calculations before granting a permit to a long heavy vehicle.

Bridge damage detection using vehicle axle-force information

Moving Force Identification (MFI) is the process of back-calculating the applied axle force histories from bridge measurements. This paper investigates the use of an MFI algorithm to detect the presence of bridge damage by monitoring calculated vehicle applied axle forces. Bridge deflections at three points along the bridge are used as the input to the algorithm. It is found that the combination of mean calculated gross vehicle weight and mean calculated axle weight ratio for a population of similar two-axle vehicles can be combined to indicate the location and severity of damage on a bridge. The bridge is modelled as a simply supported beam and deflections at the quarter point, midpoint and three quarter point are used as the inputs to the MFI algorithm. The method is shown to work best when damage is closer to the centre of the bridge.

Cross Tension Prestressed Concrete Pavements Temperature Stresses

Temperature fields and stresses of Cross Tension Retard-bonded Prestressed Concrete Pavements (CTRPCP), which are constituted by cross tension retard-bonded prestressed concrete slabs, sand gravel sliding layers, and semi-rigid bases, are studied. First, first, second, and fourth types heat transfer boundary conditions are programmed to analysis the CTRPCP’ transient temperature fields, on ABAQUS heat transfer analysis plat form. Then, the temperature fields are imported into the mechanical model to implement coupled thermo-mechanic analysis is to obtain temperature stresses of CTRPCP. On this basis, axle force gauge and vernier caliper are installed on test pavement to measure the prestressed reinforcement axial forces and displacement changes of pavement slab end with temperature changes in typical summer cloudless conditions. By comparing with the results of numerical analysis, the rationality and accuracy of the calculation model of coupled thermo-mechanical analysis of concrete pavement are verified.

Forced in-plane vibration of a thick ring on a unilateral elastic foundation

Most existing studies of a deformable ring on elastic foundation rely on the assumption of a linear foundation. These assumptions are insufficient in cases where the foundation may have a unilateral stiffness that vanishes in compression or tension such as in non-pneumatic tires and bushing bearings. This paper analyzes the in-plane dynamics of such a thick ring on a unilateral elastic foundation, specifically, on a two-parameter unilateral elastic foundation, where the stiffness of the foundation is treated as linear in the circumferential direction but unilateral (i.e. collapsible or tensionless) in the radial direction. The thick ring is modeled as an orthotropic and extensible circular Timoshenko beam. An arbitrarily distributed time-varying in-plane force is considered as the excitation. The Equations of Motion are explicitly derived and a solution method is proposed that uses an implicit Newmark scheme for the time domain solution and an iterative compensation approach to determine the unilateral zone of the foundation at each time step. The dynamic axle force transmission is also analyzed. Illustrative forced vibration responses obtained from the proposed model and solution method are compared with those obtained from a finite element model.

Independent Wheel Effects in Real Time Estimation of Tire-Road Friction Coefficient from Steering Torque

Improvement of control technologies and increased public acceptance of active systems on vehicles has led to greater implementation of safety critical assistance systems in production vehicles. However, the estimate of tire friction coefficient utilized within these systems is often obtained using only data from inertial sensors in which the tire friction is weakly represented. In contrast, skilled human drivers utilize steering torque to obtain a sense of the surface friction. In theory, this approach can also be utilized with electric power steering or steer-by-wire technologies, but there are significant challenges in obtaining and interpreting data from the steering system including the signal characteristics of steering torque measurements and the well-known problem of practical measurement of tire slip angles. More importantly, a problem often lost in modeling assumptions is in left/right asymmetry of the steering torques. The work presented in this paper illustrates the weak signal-to-noise ratio for steering torque in carefully controlled experiments and demonstrates that the lumped-axle assumption may lead to poor estimates of the front axle peak force value when attempting to predict it at slip angles less than those required for full saturation of both wheels.

Metrological approach to the force exerted by the axle of a road vehicle in motion carrying liquid

Weigh-in-motion (WIM) systems are used for identifying the dynamic force exerted on the ground by axles of a vehicle. These systems are important for monitoring the gross vehicle weight and the vehicle axle load. Overweighted trucks on the roads increase pavement damage and traffic accidents. Knowing the accuracy of WIM systems is necessary. In the case of liquid transport the ‘sloshing effect’ affects this accuracy. This paper aims to analyze the dynamic measurement of the axle forces in vehicles carrying liquid during WIM up to 6 km h−1. Laboratory experiments using one vehicle with six axles and liquid loads on different levels in weighing instruments are presented. A non-linear computational multi-mass-springs model was developed and laboratory experiments were carried out to show the acceleration influences on axle forces of vehicles with six axles and with and without baffles to vary the ‘sloshing effect’.

Active Control of Structure-Borne Road Noise Based on the Separation of Front and Rear Structural Road Noise Related Dynamics

Axle forces from tire-road interaction can excite different structural resonances of the vehicle hence a high number of sensors is required for observing and separating all the vibrations dynamics that are coherent with the cabin noise. Feed-forward road noise control strategies adopted so far rely mainly on capturing these dynamics and thus the number of sensors constitutes one major limitation of this approach. Therefore there is a necessity for reducing the number of sensors without degrading the performance of an ANC system. In the past coherence function analysis has been found to be a useful tool for optimizing the sensor location. In this case coherence function mapping was performed between an array of vibration sensors and the headrest microphones in order to identify the locations on the structure that are highly correlated with road noise bands in the compartment. A vehicle with an advanced suspension system was used for applying the method and defining some locations as reference signals for feed-forward active road noise control. Three different real-time control experiments were performed with structure-borne road noise simulated by applying broad band random forces to tires through shaker transducers. A single reference feed-forward adaptive controller evaluated the signals from each sensor location with simulated road noise excitation applied to: front wheels only, rear wheels only and whole vehicle. This way it is demonstrated that the control can be focused at specific road noise bands with a low number of sensors.