Multiple Axles Research Articles

차량 동역학 기반 다축 동력 전기 차량의 부하 최적화 로직 개발

Abstract : Recently many kinds of electric vehicles have been developed as many governments demand the environ-mental friendly vehicles. In this paper, study of load optimization for the electric vehicle which has multiple axle power system was conducted. For the analysis of the vehicle which has three or four driving axles, a method based on the geometry and assumptions that considering axles as a spring model and normal forces of the axles are proportional to the displacement of the axles was applied with basic vehicle dynamics. With the developed vehicle analysis technique, algorithm to find the optimal motor operating points was developed. Using this algorithm, it was possible to find the optimization of vehicle load distribution for multiple axles according to the driving cycles. Also, control logic for the vehicle can be developed based on the optimization simulation results. Key words : Multiple axle power system( 다축 동력 시스템), Electric vehicle( 전기 차량), Vehicle dynamics( 차량 동역학), Load optimization(부하 최적화), Optimization logic(최적화 로직)

Fatigue life prediction of an asphalt pavement subjected to multiple axle loadings with viscoelastic FEM

A model for determining bituminous pavement degradation due to multiple-axle moving traffic loads is presented. The developmental work has been based on a viscoelastic finite element method (FEM) dedicated to bituminous pavements subjected to multiple-axle traffic loads, through reliance on the following variables: pavement structure, load speed, load configuration, and bituminous material temperature. The Load Equivalent Factor (LEF) relative to various axle configurations is approximately proportional to the number of axles within a given axle group. For flexible pavements, the fatigue life predictions using the Homsi model exceed the other two models (i.e. the French standard fatigue law, developed by LCPC–SETRA [7], and the interface fatigue law developed by Diakhaté et al. [31]). Results obtained indicate that the design concept based on bending fatigue in bituminous layers is insufficient to realistically predict the degradation of a bituminous pavement structure. The phenomenon of shear at bituminous interfaces must also be taken into account, as revealed by simulation results for the degradation of two pavement structures from the French design code [8] (i.e. flexible pavement and thick asphalt pavement). For the thick asphalt pavement structure, the main damage mode is of the “bottom-up cracking” type, whereas “interface cracking” damage is typically displayed for flexible pavements. Even before determining life expectancy by means of fatigue models, the LEF clearly indicates in every pavement structure the spot where degradation was most severe (at either the interface or bottom of asphalt layers).

Effects of multiple axles on the lateral dynamics of multi-articulated vehicles

This paper describes an analytical study of the lateral dynamics of multi-articulated vehicles with multiple axles. A linear planar model of vehicle dynamics is adopted for multiple-axle vehicle combinations with an optional number of trailers. Two tractor and double-trailer combinations are examined for their directional stability and response. Non-oscillatory stability and steering sensitivity in steady-state turning and lane changing are analysed using a stability factor of multiple-axle vehicle combinations. Off-tracking in the steady-state turning of multiple-axle vehicle combinations is also analysed. Numerical calculations for oscillatory stability, steering sensitivity, and off-tracking are presented for multiple-axle vehicle combinations.

Efficiency sensitivity analysis of a hydrostatic transmission for an off-road multiple axle vehicle

There is a large variety of multiple driven axle vehicles. Some of the most common are the 3-axle rigid vehicles and the 4-axle articulated vehicles, which can in some cases have different steering mechanisms, adaptive suspension, etc. This last kind of vehicles usually have very complex transmission configurations. Moreover, the required torques in each of the wheels can be very different, especially when the vehicle is working in rough terrains. The aim of this work is to study and model the driveline of this kind of vehicles, when using a hydrostatic transmission, from the performance and efficiency point of view, by analysing the influence of the operating conditions in the transmission efficiency. A global model is used to quantify the power flow in each of the transmission elements and the overall performance of the entire vehicle driveline, given the operating conditions thereof. A sensitivity analysis has also been done showing the influence of vehicle speed, rolling resistance, terrain slope and hydraulic motors displacement in the overall transmission efficiency. The interest of this work is also to make a contribution to the literature in the field of global modelling of drivelines under variable operating conditions and its application to ATVs. One important aspect is the influence of different actuation requirements that occur in different wheels at the same time. The results show that the overall performance of the transmission is highly dependent on operating conditions, on the selected transmission configuration and on the used components.

Analysis of a hydrostatic transmission driveline for its use in off-road multiple axle vehicles

There is a vast range of off-road multi-axle wheeled vehicle configurations. Some of the most common are the three axle rigid vehicles or the four axle articulated vehicles. However, these types of vehicles have the problem of using very complex transmission configurations. In addition, the requirements in terms of torque in each of the wheels are quite variable and non uniform. This work aims to model and study, from the standpoint of performance and energy efficiency, the driveline of such vehicles. The modelling process for the design and analysis of a hydrostatic transmission aimed at off-road multiple axle vehicles has been conceptually described. Mathematical models for the main components of the transmission and a global model of the driveline have been defined. A specific example study is presented, applying the described procedure. Results show that the overall performance of the transmission is highly dependent on the operating conditions, on the selected configuration and on the used components. The results also show that the actual instantaneous efficiency of each of the components is usually far below their maximum catalogue value. In the case study efficiencies up to 64% have been reached for the overall transmission.

Active roll control for rollover prevention of heavy articulated vehicles with multiple-rollover-index minimisation

This paper presents the application of a nominal control design algorithm for rollover prevention of heavy articulated vehicles with active anti-roll-bar control. This proposed methodology is based on an extension of linear quadratic regulator control for ‘state derivative-induced (control coupled) output regulation’ problems. For heavy articulated vehicles with multiple axles, a performance index with multiple rollover indices is proposed. The proposed methodology allows us to compare the usefulness of various control configurations (i.e. actuators at different axles of the vehicle) based on the interaction of this control configuration with vehicle dynamics. Application of this methodology to a specific heavy articulated vehicle with a tractor semi-trailer shows that a single active anti-roll-bar system at the trailer unit gives better performance than multiple-axle actuators at tractor and trailer together with the single lane change manoeuvre as the external disturbance. Thus, the proposed methodology of this paper not only highlights the importance of the interactions between control and vehicle dynamics in rollover prevention problems but, in fact, proposes a novel technique to exploit the benefits of these interactions judiciously.

Vibrational and acoustical response of a railroad bridge with vehicle loading

A finite element model has been developed for a Pratt truss railroad bridge located at Ft. Leonard Wood, MO. This model was used to investigate the vibration responses of the bridge under vehicle loading. Modeling results have been obtained for a single axle with two wheels traversing the bridge at different speeds. Superposition of multiple axles have been used to represent various combinations of locomotives and flatcars transiting the bridge. The analysis includes examining the vibrational response of the bridge. The output of the vibration response is used as an input to an acoustic FE model to determine the vibrational modes that radiate infrasound. The vibration and acoustic models of the railroad bridge will be reviewed and results from the analysis will be presented. Experimental results will also be presented.

En Route to a Molecular Sheaf: Active Metal Template Synthesis of a [3]Rotaxane with Two Axles Threaded through One Ring

We report that a 2,2':6',2″-terpyridylmacrocycle-Ni complex can efficiently mediate the threading of two alkyl chains with bulky end groups in an active metal template sp(3)-carbon-to-sp(3)-carbon homocoupling reaction, resulting in a rare example of a doubly threaded [3]rotaxane in up to 51% yield. The unusual architecture is confirmed by X-ray crystallography (the first time that a one-ring-two-thread [3]rotaxane has been characterized in the solid state) and is found to be stable with respect to dethreading despite the large ring size of the macrocycle. Through such active template reactions, in principle, a macrocycle should be able to assemble as many axles in its cavity as the size of the ring and the stoppers will allow. A general method for threading multiple axles through a macrocycle adds significantly to the tools available for the synthesis of different types of rotaxane architectures.

Multiple axle loadings. Shape parameters and their effect on the fatigue life of asphalt mixtures

Multiple axle loadings. Shape parameters and their effect on the fatigue life of asphalt mixtures

밀도추정함수와 평균보정계수를 이용한 BWIM 알고리즘의 현장실험 적용

본 논문은 변형률 계측데이터를 사용하는 신뢰성 및 정확성을 증진된 BWIM(Bridge Weigh-In-Motion) 알고리즘을 개발하고, 이를 교량에 대한 다양한 실험을 통해 검증하고자 하는 것이다. 본 논문에서는 밀도추정함수와 평균보정계수를 이용한 BWIM 알고리즘을 제시한다. 밀도추정함수는 다축하중을 추정할 때 신뢰할 수 있게 적용할 수 있음을 입증하였으며, 평균보정계수는 이론 계산된 모멘트와 계측된 변형률에서 계산한 모멘트 사이의 전반적인 오차를 최소화하기 위해 적용된다. 개발된 알고리즘은 수치예제, 실내모형실험 그리고 다주형 합성교량에 대한 현장실험을 통해 성공적으로 검증하였다. The paper aims at developing a more reliable and accurate BWIM(Bridge Weigh-In-Motion) algorithm using measured strain data and examining its efficiency with various tests on bridges. It proposes a BWIM algorithm using density estimation function and average modification factor for moment-strain relationship. Density estimation function has been proved to be reliably applied when multiple axle loads are estimated. An average modification factor is applied to minimize overall error that can be encountered between theoretically computed moments and measured strains at multiple locations in a bridge. The developed algorithm has been successfully examined through numerical simulations, laboratory tests, and also by field tests on a multi-girder composite bridge.

Evaluation of fatigue and rut damage prediction methods for asphalt concrete pavements subjected to multiple axle loads

The new Mechanistic–Empirical Pavement Design Guide (MEPDG) developed under NCHRP 1-37A does away with the American Association of State Highway and Transportation Officials-derived equivalent single axle load concept and calculates damage caused by various axle configurations directly. However, the calculation of pavement damage caused by multiple axles (tandem, tridem, etc.) is significantly affected by the summation method used to describe the response of the pavement due to the passage of a given axle type or truck configuration. In this paper, the results from different methods of accounting for the passage of a given axle group are compared using laboratory fatigue and rut data from repeated cyclic load tests. The evaluation criterion for these different summation methods was the degree of agreement with the measured laboratory performance. The results show that for fatigue damage, dissipated energy and strain area methods have an excellent agreement with the laboratory values, whereas peak and peak mid-way methods have poor agreement. This implies that it is important to consider the entire strain pulse when calculating fatigue damage under multiple axles. For rutting damage, the peak strain method has the best agreement with the laboratory values, whereas dissipated energy and peak mid-way methods underestimate the rutting damage. Finally, the MEPDG procedure for calculating the strain under multiple axles considerably underestimates the damage for both fatigue and rutting. However, model calibration in the MEPDG does improve the prediction of the damage due to multiple axles for fatigue and to a lesser extent for rutting.

Directional Response of Multi-Articulated Vehicles with Multiple Axles to Steering Input

Directional response and directional stability of vehicle combinations are the main research topics in vehicle safety. This paper uses simplified mathematical models to analyze the steering sensitivity in lane-change maneuvers of multi-articulated vehicles with multiple axles. It also calculates the frequency response, pole, and zero in the transfer functions of each variable for two types of tractor and double-trailer combinations having multiple axles. The following conclusions are drawn. (1) Steering sensitivity of multi-articulated vehicles with multiple axles in lane-change maneuvers is composed of steering sensitivity in steady-state turns and the parameters of lane-change maneuvers. (2) The effect of the number of trailer axles on the damping ratio of zero is larger than that of the other parameters for multiple axles. (3) A large steering angle is necessary to change running lanes for multi-articulated vehicles with multiple axles that have low steering sensitivity in lane-change maneuvers; therefore, the rise time is short. Moreover, if the vehicle combination has a low damping ratio of oscillatory modes, the settling time is long, and the overshoot and maximum deviation are large.

Directional Response of Multi-Articulated Vehicles with Multiple Axles to Steering Input

Directional response and directional stability of vehicle combinations are main research topics in vehicle safety. This paper analyzes the steering sensitivity in lane-change maneuvers of multi-articulated vehicles with multiple axles using simplified mathematical models. It also calculates the frequency response, pole, and zero in the transfer functions of each variable for two types of tractor-double-trailer, a tractor-semitrailer and a truck-full-trailer having multiple axles. The following conclusions are drawn. (1) The steering sensitivity of multi-articulated vehicles with multiple axles in lane-change maneuvers is composed of steering sensitivity in steady-state turns and the parameters of lane-change maneuvers. (2) The effect of the number of trailer axles on the damping ratio of zero is larger than that of the other parameters for multiple axles. (3) A large steering angle is necessary to change running lanes for multi-articulated vehicles with multiple axles that have low steering sensitivity in lane-change maneuvers; therefore, the rise time is short. Moreover, if the vehicle combination has a low damping ratio of oscillatory modes, the settling time is long, and the overshoot and maximum deviation are large.

Directional Stability of Multi-Articulated Vehicles with Multiple Axles

This paper presents a theoretical study on the directional stability of multi-articulated vehicles with multiple axles. The vehicle dynamics model is derived in the horizontal plane having degrees of freedom of vehicle side-slipping and yawing. For an equal vertical load of each axle as well as an equal cornering coefficient of each wheel of the multiple axles, the equations of motion can be reduced to ones with a single axle and additional terms that are functions of the number of axles and the distances between them. Two types of tractor and double-trailer combinations with multiple axles are examined with regard to straight running stability as well as steering sensitivity in steady-state turning. Non-oscillatory stability incorporating steering sensitivity is analyzed using the stability factor of multiple-axle vehicle combinations. A parameter study of oscillatory stability and steering sensitivity is conducted, and the following conclusions are drawn. (1) The terms on multiple axles are added in the tractor yawing moment and part of the trailer yawing moment. (2) Multiple-axle vehicles differ from single-axle vehicles in non-oscillatory stability and steering sensitivity. (3) A multiple-axle dolly improves oscillatory stability.

Multiple axle loadings

ABSTRACT The effect of multiple axle loads on the fatigue life of asphalt pavements is a key issue dealing with the effect of heavy trucks on pavement distresses. Equivalent Single Axle loads are currently calculated with simplified hypotheses. This is an important stake for the ecological transportation: increasing the load per truck results in decreasing the emission of toxic gases per ton of transported goods. To study the effect of multiple axles, real displacement signals in the pavement are needed. The LCPC's accelerated testing facility (Nantes, France) enables the measurement of real loading signals in an experimental pavement. Parameters describing the pavement strain curves were computed for this database. A factorial analysis gives four independent parameters that define an experimental plan of a campaign of fatigue tests whose aim is to identify how the fatigue life is affected by the shape parameters.

Application of the structural articulation method to dynamic impact loading of railway bridges – a case study

This article demonstrates a practical application of the structural articulation method. An existing prototype railway bridge was selected to compare our new method with the industry codes of practice. The response history and dynamic increment of the bridge were investigated through a variety of methods: lump sum mass analysis (LSMA) and suspension system analysis (SSA) for a single-axle force, and SSA for multi-axle forces. We considered both a local irregularity and a global sinusoidal irregularity. The dynamic impact load induced by either form of track irregularity increases approximately linearly with the vehicle speed up to a certain point, then tends to decrease gradually. This behaviour reveals that the dynamic impact load induced by track irregularities is dominated by the resonance of the bridge. If a bridge must support multiple axles, or if an especially accurate dynamic impact factor is required for safety reasons, then multi-axle SSA is recommended because this approach is the most accurate and likely to produce a weaker response than single-axle analysis. The random irregularity is generated by the stochastic track irregularity process. It is found that the dynamic impact load induced by the random irregularity is negligible, compared with the deterministic irregularity.

多軸・多重連結車両の方向安定性解析(機械力学,計測,自動制御)

多軸・多重連結車両の方向安定性解析(機械力学,計測,自動制御)

Comparative Linear Analysis of Alternative Layouts of Heavy Goods Vehicles

This paper presents comparative analyses of steering wheel responses of various layouts for heavy goods vehicles, including rigid and articulated configurations. Newton and Lagrange techniques have been adopted to formulate and verify the generalized linear model for multi-axle rigid and articulated vehicles. The model is then used to simulate, analyze and compare steering angle response of a variety of commercially available vehicles. The study includes the analyses of steady state response and dynamic behavior for different layouts in terms of axle positions, number of axles and multiple steered axles.

A Laboratory Investigation of the Effect of Multiple Axle and Truck Configurations on HMA Mixture Rutting

ABSTRACT Few studies have investigated pavement damage resulting from different axle and truck configurations, and they were generally limited to single and tandem axles. The unconfined compression cyclic load test with loading cycles that simulate different axle and truck configurations was used to examine their relative effect on permanent deformation of an asphalt mixture. The laboratory investigation indicates that the rutting damage due to different axle configurations is approximately proportional to the number of axles. However, the effect of rest period between axles groups within a truck configuration is significant. Calculating truck rutting damage by simply summing the vertical permanent deformation corresponding to its constituent axle groups results in erroneous predictions. The application of Miner's rule results in improved truck rutting damage predictions for a wider range of truck configurations, although it does not account for the effect of rest periods within a truck configuration. Fin...

Mathematical models for motion of the rear ends of vehicles

A new treatment of the path of the rear wheels of single and multiple axle vehicles produces simple first order differential equations for the motion of the rear wheels relative to the front wheels. We show for the first time, under the assumption of no slipping, that the path of the rear wheels depends only on the path of the front wheels and not on the vehicle speed. We examine motion along straight, circular and winding roads, giving closed form solutions in the first two cases. We also provide a straightforward algorithm for computing vehicle offtracking for any road geometry. We believe these results will be of significant benefit to road designers.