Truck Braking Research Articles

Effects of heavy truck braking on inverted asphalt pavement considering vehicle dynamics

Inverted asphalt pavement is an innovative pavement structure where the unbound aggregate base (UAB) is sandwiched between the asphalt concrete (AC) layer and cement-treated base (CTB). This structure has the potential to improve rutting resistance of pavement and prevent propagation of reflective cracks. However, its implementation has been limited due to the lack of experience. In addition, the braking condition of the vehicle applied on the pavement surface plays a significant role on the pavement responses, thereby affecting its service life. This study conducted a simulation using finite layer method to investigate the effects of heavy truck braking on inverted asphalt pavement considering vehicle dynamics. The results indicated that truck braking would generate a significant horizontal load and change the magnitude of the vertical load at each axle. Furthermore, the impact of vertical load on mechanical responses would gradually enhance and eventually dominate with increasing pavement depth. It was also observed that when the truck was treated as a whole, vehicle braking would result in a 3.2% to 10.2% increase in critical responses, but cause a 0.023% and 31.7% decrease in predicted rutting and life respectively. Among three truck axles, the effect of driving axle was close to that of the entire truck, but the effect of other axles was greater or lower than that of the entire truck. A comparison of three inverted pavements found that a thick AC layer could effectively reduce the critical responses and extend the pavement life. Furthermore, a thick CTB layer could also achieve most of the above purposes due to higher integral stiffness of pavement.

Analysis of truck braking using multiple simulations

In the field of road vehicles, the merging of mechanical assemblies and electronic computing architecture has become indispensable. In the present paper, a thorough study of the braking performance of heavy goods vehicles is presented. Operating conditions and other influencing factors during use create multiple combinations that influence the behavior and performance of braking systems in different ways. However, for such a speed of development, the dedicated means of research become insufficient, thus new study methods are needed to guarantee complex results with a minimum of consumed resources. Such a variant of the study is also addressed in this paper, where the results are obtained based on multiple simulations, carried out simultaneously, but in a much shorter time than in the experimental cases and with a large volume of data.

Influence of road profiles and truck braking on the dynamic load transfer to the pavement

ABSTRACT During the braking manoeuvre of a vehicle on a pavement, the mechanics associated with load transfer is complex due to the presence of slip, load shift between the front and rear axles, and development of longitudinal forces. The road profiles, braking intensity, truck mass, and speed during braking play a critical role here. This investigation reports an attempt to collect such data. A unique Hardware-in-Loop set-up was integrated with vehicle dynamics software, TruckMaker, to perform a realistic braking manoeuvre. Three truck loadings were chosen from the axle load survey conducted in the field (unladen, laden, and overloaded). Three ISO road profiles (A, B, C) generated using the power spectral density approach, three initial speeds (30, 50, and 80 km/h), and three braking intensities (Partial (10%), Partial (45%), and Complete (100%)) were chosen for the simulation. In total 81 simulations were performed considering all the above-said factors. From the analysis of wheel slip values, it was identified that the wheels of unladen trucks lock during complete braking, irrespective of the speeds and road profiles. The complete braking manoeuvre for all vehicle types showed more load shift from the rear axle to the front axle compared to partial braking manoeuvres. Also, the unladen trucks were found to transfer more percentage (>50%) of their rear axle load to the front axle during braking. The maximum longitudinal force developed at the tyre-pavement interface was found to be independent of the loading conditions during complete braking.

The effect of interface modifications combination of multiple friction blocks on truck brake squeal

In order to study the effect of interface modifications combination of multiple friction blocks on truck brake squeal, a field test is carried out in this study. In the test, the vibration acceleration and the noise signals of the truck braking system are collected. The test results show that the high frequency squeal noise during braking is resulted from the frictional vibration of the braking system. A simplified finite element model of the heavy truck braking system is stablished to investigate the effect of slotting and chamfering of friction block on brake squeal. The results of complex eigenvalue analysis indicate that the interface modifications have a great influence on truck brake squeal. A proper combination of slotting and chamfering of friction blocks is useful for the reduction of brake squeal tendency. This study can provide guidance for the design and optimization of silent braking system.

Study of the control algorithm of the braking system of an autonomous haul truck braking system with the use of imitational models

The paper considers different ways of controlling the braking systems of haul trucks. The general approaches used in the development of control systems for such braking systems are described. Methods of testing and imitational mathematical models, used for the analysis of brake system control systems operation, are presented. The developed control system and the imitational model allow us to analyze the brake system behavior under different operating modes of a haul truck.

Research and implementation of new-type supercapacitor and battery hybrid energy storage system

When a dump truck brakes, it is difficult to effectively absorb the braking energy due to the transient mutation of braking energy. At the same time, braking energy production is too high to store easily. Focusing on these problems, this paper proposes a new type of two-stage series supercapacitor and battery (SP&B) hybrid energy storage system (ESS). Using the characteristics of supercapacitors, which can charge and discharge quickly with large currents, the system combines the supercapacitors with a battery with a high energy storage capacity. This allows sudden large currents to be absorbed and released rapidly, while large amounts of energy can be stored. This system can also reduce the charge and discharge times of the SP&B to meet the working requirements of dump truck braking while improving the service life of the system. After completion of the research and implementation of the proposed SP&B hybrid ESS, a laboratory dynamic model was set up as an experimental platform and vehicle operation experiments were performed. The obtained results show that the energy recovery efficiency of the hybrid ESS can reach 53.5%, which can realize both security and stability for dump truck braking energy recovery and utilization (BER&U) systems.

Asphalt road surface vibration and force distribution generated by pickup truck braking

This paper presents a method for dynamic vibration and force measurement using a microcontroller. In the experiment, data were obtained by vibration frequency measurement at the asphalt road surface when the vehicle brakes were applied, and the data were analyzed using additional equipment and software. By using the SW-420 device, frequencies in the range of 10–1000 Hz were applied and tested. The results obtained indicated that the proposed system can be used to determine the force acting on the road surface while the vehicle is in motion. The estimated forces were within the range of 0.20–4.10 × 1010 N at velocities of 20–100 km·h−1. A relative maximum error of 0.20% was achieved.

Design philosophy and requirements of granular wear surface thickness for bridges subjected to extreme truck load

With the increasing demand to build bridge systems to transport extremely heavy trucks in the mining industry, advancements in the current bridge design provisions are needed to account for the extraordinary weight and configuration of the mining trucks. There are no design provisions specifically developed to determine the granular wear surface thickness for haul road bridges. This research study proposed a design philosophy for bridge gravel wear surface design and developed a set of provisions for possible inclusion in international bridge and pavement codes. Three design requirements were developed, among which are two compulsory requirements and one optional requirement. The two compulsory design requirements include: Maintain gravel cohesion, and prevent concrete deck cracking during the passage of the design vehicle. The optional design requirement is: Minimize concrete deck cracking during the rare event of truck braking. Design recommendations and design-aids pertaining to each design requirement...

Hardware-in-the-Loop Pneumatic Braking System for Heavy Truck Testing of Advanced Electronic Safety Interventions

The rapid innovation underway with vehicle brake safety systems leads to extensive evaluation and testing by system developers and regulatory agencies. The ability to evaluate complex heavy truck braking systems is potentially more rapid and economical through hardware-in-the-loop (HiL) simulation which employs the actual electronics and vehicle hardware. Though the initial HiL system development is time consuming and expensive, tests conducted on the completed system do not require track time, fuel, vehicle maintenance, or technician labor for driving or truck configuration changes. Truck and trailer configuration and loading as well as test scenarios can be rapidly adjusted within the vehicle dynamics simulation software to evaluate the performance of automated safety interventions (such as ESC) over a wide range of conditions. Hardware-in-the-loop simulation does not obviate the need for all track testing; vehicle models for simulation must be validated against track data for each truck platform. But HiL simulation can supplement and extend track data for tests at higher speeds, low friction surfaces, and alternate vehicle configurations. A HiL pneumatic braking system was developed for this purpose by the National Highway Traffic Safety Administration, with the goal of evaluating performance as it relates to safety. This paper describes the system in detail and includes some sample results of the testing. Language: en

Safety Testing of an Improved Brake System for Automatic Platooning of Trucks

An automatic platooning technology for energy-saving logistics utilizing intelligent transportation systems (ITS) technologies have been developed in the Energy-Saving ITS Project of Japan. The automatic platooning of trucks is studied to save energy consumption by reducing air resistance. Considering the experimental testing and practical application for automatic platooning, it is important to ensure driver safety, and high levels of safety and efficacy are required for truck braking systems. Therefore, a new brake system for automatic platooning needs to be developed. In this study, two approaches are proposed. One is to design a secondary brake system working in a fail situation with the main brake system, the other is to adjust for different maximum decelerations for the preceding and following trucks. In the first step, the proposed measure was investigated using an actual vehicle and a simulation experiment. Based on this, the proposed brake system was developed and mounted on the experimental trucks, and full brake testing was carried out to evaluate its effectiveness. The experimental result showed that the improved brake system was effective in ensuring brake safety by incorporating these functions in the trucks.

Braking performance and influence of microstructure of advanced cast irons for heavy goods vehicle brake discs

It is well known that truck brakes dissipate several megajoules of energy every few seconds, which leads to high thermal stresses in the rubbing parts. Therefore, premature failure by cracking of truck brake discs is a matter of major concern. Improving the design and material of brake discs may enhance braking performance. This study focuses on the latter aspect and was carried out with the aim of developing new material solutions for increasing disc lifespan. To do so, braking experiments were conducted on a specially designed braking tribometer. The brake pads that were used were made from a commercial brake lining material. Two advanced cast irons with different graphite morphology were studied in comparison with the lamellar grey cast iron commonly used for brake disc. To verify the friction and thermal behaviour of the two cast irons, braking tests were carried out as a series of stop-brakings with increasing dissipated power and energy and as a series of slowdowns to achieve heat accumulation effects. Thermal phenomena were studied through bulk temperature measurements and infrared monitoring of the disc surface. Friction behaviour, braking performance and variations in thermal loading were analysed in relation to the level of energy dissipation. The two advanced cast irons and lamellar cast iron had equivalent braking performance and stored similar amounts of heat, according to their thermophysical properties. Observations of the rubbing surfaces indicated damage mechanisms affected by the graphite morphology. Less plastic deformation on the surface was observed with an interdendritic graphite.

HEADWAY TIME AND CRASHES AMONG NOVICE TEENS AND EXPERIENCED ADULT DRIVERS IN A SIMULATED LEAD TRUCK BRAKING SCENARIO.

Driving simulators can be used to evaluate driving performance under controlled, safe conditions. Teen drivers are at particular risk for motor vehicle crashes and simulated driving can provide important information on performance. We developed a new simulator protocol, the Simulated Driving Assessment (SDA), with the goal of providing a new tool for driver assessment and a common outcome measure for evaluation of training programs. As an initial effort to examine the validity of the SDA to differentiate performance according to experience, this analysis compared driving behaviors and crashes between novice teens (n=20) and experienced adults (n=17) on a high fidelity simulator for one common crash scenario, a rear-end crash. We examined headway time and crashes during a lead truck with sudden braking event in our SDA. We found that 35% of the novice teens crashed and none of the experienced adults crashed in this lead truck braking event; 50% of the teens versus 25% of the adults had a headway time <3 seconds at the time of truck braking. Among the 10 teens with <3 seconds headway time, 70% crashed. Among all participants with a headway time of 2-3 seconds, further investigation revealed descriptive differences in throttle position and brake pedal force when comparing teens who crashed, teens who did not crash and adults (none of whom crashed). Even with a relatively small sample, we found statistically significant differences in headway time for adults and teens, providing preliminary construct validation for our new SDA.

Light Truck Braking System Match and Optimization

In order to make the front and rear axle braking force close to the ideal braking force distribution curves, this paper presents a new idea about the design of automotive brake systems. Firstly, the paper has studied the mathematical conversion relationship from the coordinate of utilization adhesion coefficient and braking strength to the coordinate of the front and rear axle braking force. On this basis, the optimal parameters and constraints complying with ECE regulation are determined. And the optimization objective is the degree of deviation between the curve of actual braking force distribution and the curve of the ideal braking force distribution. Taking a light truck for example, genetic algorithm is used to optimize the vehicle front-rear braking force distribution in the platform of MATLAB. Finally, it is proved that the result of global optimization can meet the design goals.

Modeling and Troubleshooting with Interventions Applied to an Auxiliary Truck Braking System

We consider computer assisted troubleshooting of complex systems, where the objective is to identify the cause of a failure and repair the system at as low expected cost as possible. Three main challenges are: the need for disassembling the system during troubleshooting, the difficulty to verify that the system is fault free, and the dependencies in between components and observations. We present a method that can return a response anytime, which allows us to obtain the best result given the available time. The work is based on a case study of an auxiliary braking system of a modern truck. We highlight practical issues related to model building and troubleshooting in a real environment.

Anytime Near-Optimal Troubleshooting Applied to an Auxiliary Truck Braking System

We consider computer assisted troubleshooting of complex systems, for example of a vehicle at a workshop. The objective is to identify the cause of a failure and repair a system at as low expected cost as possible. Three main challenges are: the need for disassembling the system during troubleshooting, the difficulty to verify that the system is fault free, and the dependencies in between components and observations. We present a method that can return a response anytime, which allows us to obtain the best result given the available time. The work is based on a case study of an auxiliary braking system of a modern truck. We highlight practical issues related to model building and troubleshooting in a real environment.

Discrete element simulation of the behavior of bulk granular material during truck braking

PurposeTo simulate the dynamic feature of bulk granular material (such as agricultural products) during sudden braking of a truck by applying discrete element method.Design/methodology/approachThe bulk granular material was modeled by the discrete element approach, in which the spherical elements were used to represent the granular particles; the interaction between two in‐adhesive particles was modeled by Hertz for normal interaction, and by Mindlin and Deresiewicz for tangential interaction; the interaction between two particles with adhesion was modeled by the JKR theory for normal interaction, and by Thornton's theory for the tangential interaction. Different initial conditions (braking speeds/accelerations) were considered. The dynamic system was numerically solved by the central difference based explicit time integration, and the dynamic impact forces were recorded to further analysis.FindingsThe computation predicted that the resultant dynamic force acting upon the front wall behaves in four stages, i.e. increasing, plateau, sharp increasing and drop with damped fluctuation. It was observed that, the shorter the breaking time is, the faster the force reaches its peak, and the greater the peak value is. The phenomenon was in good agreement with physical principals and common knowledge.Research limitations/implicationsIt is an application of the discrete element method and, therefore, no important contribution is made to advance the methodology.Practical implicationsThe proposed modeling approach may serve as a useful tool for advanced design of trucks.Originality/valueThis paper is the first to apply the advanced discrete element method to the problem concerned.

Axle load shifts during truck braking and their implications for bridge and pavement design

The axle load shifts of four truck types during braking are estimated using theoretical braking models and the implications of these axle load shifts for bridge and pavement design are explored. The truck types examined are a three-axle straight truck, a five-axle tractor semi-trailer, a seven-axle tractor semi-trailer with two air-lift belly axles, and a seven-axle B-train tractor-double trailer, each loaded to legal Ontario limits with weigh-out commodities. Each of the truck types experienced a substantial load transfer to the front steering axles under braking, mainly from the rear tandem axle groups, where the front axle load increase varied from 38 to 48%. The bridge design implications of the load shifts are examined in terms of the Ontario Bridge Formula and the moments induced in simple-span bridges compared with the moments induced by a reference design truck. For the braking model used, the decelerations and associated shifts in axle load do not lead to higher forces for bridge design and evaluation. The pavement damage implications are analyzed in terms of load equivalency functions derived from some load tests conducted at a number of pavement sites across Canada in 1986. These equivalencies increased up to 50% of the static values for the three-axle truck at maximum braking. It is suggested that the major damage implications are at intersections in urban areas and that increased structural sections could be designed to handle the increased equivalencies. Key words: bridge design, pavement design, truck braking, truck loads, pavement damage, bridge damage.

Parametric analyses of large truck braking efficiencies

Simplified braking models are used to analyze the braking efficiencies of a range of truck types under a variety of loading conditions and tire–pavement coefficients of friction. These analyses show that while most of the fully loaded trucks are capable of achieving a braking efficiency of 70%, the braking efficiencies of the unloaded or partially unloaded trucks deteriorate substantially. A bobtail tractor, an unloaded semi-trailer with tridem rear axle group and two air-lift belly axles, and a B-train double trailer with rear trailer unloaded have estimated braking efficiencies of 40–50%. The braking distances required by the unloaded and partially loaded vehicles from a 100 km/h operating speed are two to four times longer than those specified in the Canadian geometric design standards. Comparisons of the model-estimated braking distances with those obtained in one set of field tests show that the models are capable of reflecting accurately observed field behaviour. The results presented in the paper demonstrate the need for a systematic review of those highway design standards that are based on the braking capabilities of vehicles using the highway system. Key words: highway geometric design, truck braking efficiency, braking distances, highway safety.

Truck braking distance and speed estimates

The most frequently cited cause of truck accidents is “speed too fast for prevailing conditions.” To cite this cause, a speed estimate is necessary. This paper shows the factors that should be considered. The factors most useful in estimating a truck's braking capability include vehicle configuration, loading, location of the centre of mass, and axles with brakes. The exact value of some of the variables is difficult to obtain.The formulation proposed in this paper builds on a simple and effective procedure used by police agencies to estimate speed from skid marks. The formula given by R. Rivers' “Traffic accident investigator's handbook” is formalized and the elements in his correction factor N are derived. Basic equations for the braking of straight trucks and combinations are derived. The difficulty of implementing the equations in practice for all but the simplest situation is obvious from the complexity of the equations. A lumping of all the parameters into a simplified form is developed based on truck stopping distances obtained from published experimental data. All the trucks in the data had well-adjusted brakes. The final equation to estimate speed from a truck's skid marks accounts for the average ability of such vehicles to stop as well as the variance in stopping ability. Key words: truck braking, braking efficiency, stopping sight distance, skid marks.