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Abstract An analysis method for the stability of combined braking system of tractor-semitrailer based on phase-plane is investigated. Based on a 9 degree of freedom model, considering longitudinal load transfer, nonlinear model of tire and other factors, the braking stability of tractor-semitrailer is analyzed graphically on the phase plane. The stability of both tractor and semitrailer with different retarder gear is validated with the energy plane, β plane, yaw angle plane and hinged angle plane. The result indicates that in the long downhill with curve condition, both tractor and semitrailer show good stability when retarder is working at 1st and 2nd gear, and when it is at 3rd gear, the tractor is close to be unstable while semitrailer is unstable already. Besides, tractor and semitrailer both lose stability when retarder is working at the 4th gear.

In 2006, there were approximately 23,500 rear-end crashes involving heavy trucks (i.e., gross vehicle weight greater than 4,536 kg). The Enhanced Rear Signaling (ERS) for Heavy Trucks project was developed by the Federal Motor Carrier Safety Administration (FMCSA) to investigate methods to reduce or mitigate those crashes where a heavy truck has been struck from behind by another vehicle. Visual warnings have been shown to be effective, assuming the following driver is looking directly at the warning display or has his/her eyes drawn to it. A visual warning can be placed where it is needed and it can be designed so that its meaning is nearly unambiguous. FMCSA contracted with the Virginia Tech Transportation Institute (VTTI) to investigate potential benefit of additional rear warning-light configurations as rear-end crash countermeasures for heavy trucks.

This paper presents an integrated design method for active trailer steering (ATS) systems of articulated heavy vehicles (AHVs). Of all contradictory design goals of AHVs, two of them, i.e. path-following at low speeds and lateral stability at high speeds, may be the most fundamental and important, which have been bothering vehicle designers and researchers. To tackle this problem, a new design synthesis approach is proposed: with design optimization techniques, the active design variables of ATS systems and passive design variables of trailers can be optimized simultaneously; the ATS controller derived from this approach has two operational modes, one for improving lateral stability at high speeds and the other for enhancing path-following at low speeds. To demonstrate the effectiveness of the proposed approach, it is applied to the design of an ATS system for an AHV with a tractor and a full trailer.

Torsional stiffness properties were developed for both a 53-foot box trailer and a 28-foot flatbed control trailer based on experimental measurements. In order to study the effect of torsional stiffness on the dynamics of a heavy truck vehicle dynamics computer model, static maneuvers were conducted comparing different torsional stiffness values to the original rigid vehicle model. Stiffness properties were first developed for a truck tractor model. It was found that the incorporation of a torsional stiffness model had only a minor effect on the overall tractor response for steady-state maneuvers up to 0.4 g lateral acceleration. The effect of torsional stiffness was also studied for the trailer portion of the existing model.

A truck-trailer combination is modeled using ADAMS/Car from MSC Software for handling and ride comfort performance simulations. The handling events include a double lane change and lateral roll stability. The ride comfort performance events include several sized half-rounds and various RMS courses. The variables for handling performance evaluation include lateral acceleration, roll angles and tire patch normal loads. The variables for ride performance evaluation are absorbed power and peak acceleration. This study considers the trailer spring stiffness, anti-roll bar and jounce bumper gap as the design variables. Through DOE simulations, we derived the response surface models of various performance variables so that we could consider the performance sensitivities to the design variables.

The objective of this study was to evaluate the concept of a heavy-duty tractor - motorized semi-trailer hybrid electric combination, which would have electric drive axles on the semi-trailer. The scope of the project included an analysis of the general concept of a power-driven semi-trailer, the positioning of the concept of the heavy-duty tractor - motorized semi-trailer hybrid electric combination in the general context of the technology, and the evaluation of the applicability of the concept for different duty cycles. Several transport activities were analyzed to determine specific duty cycles for heavy-duty vehicles: highway line haul and regional haul, construction haul, and off-highway hauling of raw materials, such as forestry transport with Class 8 and off-highway tractor-trailer combinations.

Due to the diversity of Heavy Duty Vehicles (HDV), the European CO2 and fuel consumption monitoring methodology for HDVs will be based on a combination of component testing and vehicle simulation. In this context, one of the key input parameters that need to be accurately defined for achieving a representative and accurate fuel consumption simulation is the vehicle's aerodynamic drag. A highly repeatable, accurate and sensitive measurement methodology was needed, in order to capture small differences in the aerodynamic characteristics of different vehicle bodies. A measurement methodology is proposed which is based on constant speed measurements on a test track, the use of torque measurement systems and wind speed measurement. In order to support the development and evaluation of the proposed approach, a series of experiments were conducted on 2 different trucks, a Daimler 40 ton truck with a semi-trailer and a DAF 18 ton rigid truck.

This paper reviews fuel-saving technologies for commercial trailers, provides an overview of the trailer market in the U.S., and explores options for policy measures at the federal level that can promote the development and deployment of trailers with improved efficiency. For trailer aerodynamics, there are many technologies that exist and are in development to target each of the three primary areas where drag occurs: 1) the tractor-trailer gap, 2) the side and underbody of the trailer, and 3) the rear end of the trailer. In addition, there are tire technologies and weight reduction opportunities for trailers, which can lead to reduced rolling resistance and inertial loss. As with the commercial vehicle sector, the trailer market is diverse, and there are a variety of sizes and configurations that are employed to meet a wide range of freight demands.

The underbody of a truck is responsible for an appreciable portion of the vehicle’s aerodynamic drag, and thus its fuel consumption. This paper investigates experimentally the flow around side-skirts, a common underbody aerodynamic device which is known to be effective at reducing vehicle drag. A full, 1/10 scale European truck model is used. The chassis of the model is designed to represent one that would be found on a typical trailer, and is fully reconfigurable. Testing is carried out in a water towing tank, which allows the correct establishment of the ground flow and rotating wheels. Optical access into the underbody is possible through the clear working section of the facility. Stereoscopic and planar Particle Image Velocimetry (PIV) set-ups are used to provide both qualitative images of and quantitative information on the flow field.

This SAE standard establishes the minimum construction and performance requirements for a combination cable consisting of 11 conductors and 4 twisted pairs for use on trucks, trailers, and dollies in conjunction with SAEJ2691. (15 pole connectors.) The cable includes both power and unjacketed SAE J1939-15 paired signal circuits along with dual ground wires to accommodate grounding requirements within the constraints of the SAE J2691 terminal capacity.

Abstract A wind-tunnel study was undertaken to investigate the drag reduction potential of two-truck platooning, in the context of understanding some of the factors that may influence the potential fuel savings and greenhouse-gas reductions. Testing was undertaken in the National Research Council Canada 2 m × 3 m Wind Tunnel with two 1/15-scale models of modern aerodynamic tractors paired with dry-van trailers configured with and without combinations of side-skirts and boat-tails. Separation distances of 0.14, 0.28, 0.49, 0.70 and 1.04 vehicle lengths were tested (3 m, 6 m, 10.5 m, 15 m, and 22.5 m full scale). Additionally, within-lane lateral offsets up to 0.31 vehicle widths (0.8 m full scale) were evaluated, along with a full-lane offset of 1.42 vehicle widths (3.7 m full scale). This study has made use of a wind-averaged-drag coefficient as the primary metric for evaluating the effect of vehicle platooning.

In this paper, dynamics and stability of an articulated vehicle in the yaw plane are examined through analysis, simulations, and vehicle testing. Control of a vehicle-trailer combination using active braking of the towing vehicle is discussed. A linear analytical model describing lateral and yaw motions of a vehicle-trailer combination is used to study the effects of parameter variations of the trailer on the dynamic stability of the system and limitations of different control strategies. The results predicted by the analytical model are confirmed by testing using a vehicle with a trailer in several configurations. Design of the trailer makes it possible to vary several critical parameters of the trailer. The test data for vehicle with trailer in different configurations is used to validate the detailed non-linear simulation model of the vehicle-trailer combination.

A time-accurate finite element model for predicting the coupled dynamic response of tanker trucks and their liquid payloads is presented along with an experimental validation of the model. The tanker truck components are modeled using rigid bodies, flexible bodies, joints and actuators. The model is validated using a full-scale army heavy class tactical trailer carrying a water tank. The trailer is placed on an n-post motion base simulator which was used to perform harmonic/ramp pitch, roll and stir excitations of the trailer in order to simulate typical road maneuvers. Experiments were carried out with an empty tank and a 65%-filled tank. The time-histories of the tires and suspension system deflections are measured for the various input motion excitations. The experiment's measurements are compared with the results predicted using the computational model. The comparison shows that the model can predict with reasonably good accuracy the test tanker-trailer's dynamic response.

Alternative implementations of a Rear Cross Traffic Alert (RCTA) system intended to actively notify drivers of the presence of rear cross-path traffic when backing were evaluated in naturalistic settings. The feature is one of several emerging technologies designed to assist drivers when backing - in this case, enhancing drivers' awareness of traffic approaching from the rear. The study allowed performance under a range of RCTA system driver interface implementations to be contrasted with conventional and wide Field of View (FOV) Rear Vision systems. Evaluations were conducted using a sample of 70 drivers under naturalistic settings and environments with repeated exposures to backing tasks. The study also made use of a staged conflict situation with a confederate vehicle in order to more precisely quantify driver behavior and system usage across drivers under controlled conflict situations.

Beam-type structural elements are generally utilized in construction of majority of the automotive structures, e.g. the buses, trailers, and solid axles. These components are usually subjected to spatially-random or uncertain load conditions during their service lives. Moreover, material properties of the beams-type structural elements may vary from a sample to another in a random manner. The situation will be more complex when both material properties and load conditions exhibit random natures in the spatial domain. In the present paper, an algorithm is presented to assess the probabilistic behavior of the beam-type vehicle's components in relation with the strength and deflection requirements. A consistent finite element reliability model that may be employed for beams with arbitrary inclinations under simultaneous spatially-random loading conditions and random material properties is introduced.

A 1:10-scale wind tunnel development program was undertaken by the National Research Council of Canada and Airshield Inc. in 1994 to develop trailer side skirts that would reduce the aerodynamic drag of single and tandem trailers. Additionally, a second wind tunnel program was performed by the NRC to evaluate the fuel-saving performance of boat-tail panels when used in conjunction with the skirt-equipped single and tandem trailers. Side skirts on tandem, 8.2-m-long trailers (all model dimensions converted to full scale) were found to reduce the wind-averaged drag coefficient at 105 km/h (65 mi/h) by 0.0758. The front pair of skirts alone produced 75% of the total drag reduction from both sets of skirts and the rear pair alone produced 40% of that from both pairs. The sum of the drag reductions from front and rear skirts separately was 115% of that when both sets were fitted, suggesting an interaction between both.

Although considerable efforts have been made with respect to the reduction of fuel consumption of trucks during the last decades, the diminishing natural resources as well as the evolution of the truck traffic require continuous improvements in the field of aerodynamics. Indeed, the forces generated by the air on the trucks may originate, depending on weather, road type, truck type, dimension, etc., up to 50% of the fuel consumption. In order to analyze the influence of proportion variations (mainly related to the length) and add-on devices on the aerodynamic performance of a truck, a representative model was first generated. This simplified geometry of a tractor-trailer was based on the geometrical data of six European OEMs: Daimler, Iveco, and MAN (tractors), Kögel, Krone and Schmitz Cargobull (trailers). The model included a reduced level of details (exterior mirrors, wheels, simplified underbody and engine block).

In this study, a closed-loop driver-truck-trailer system model is established with ADAMS/Car. A double lane change maneuver (DLCM) path boundary is set up based on the NATO AVTP 03-160W requirement. The best driver preview path at a given speed to pass the DLCM is derived from optimization of the closed-loop driver-vehicle-road system, where the objective is to successfully pass the DLCM at the given forward speed. This must be done without violating the maneuver boundary, lifting any tires off the ground, as well as staying within the Driver's steering effort limit. Depending upon the Driver's control strategy, which is reflected by the formulation of the optimal objective, the dynamic responses of the truck-trailer combination will vary. Two extreme conditions are discussed in this study: full and no consideration of trailer, respectively, when negotiating the DLCM.

Improving driving safety and freeway capacity is an indispensable research issue for road vehicles, especially for tractor semi-trailers, which on the one hand exhibit unstable motion modes at high speeds due to their articulated configurations and undertake the largest part of freight transportation on freeways. Automatic driving is rated as the ultimate solution of vehicle safety since it can significantly reduce accidents resulting from human driver errors. Proposed in this paper is a gain-scheduled PID controller for automatic path-following of a tractor semi-trailer. The PID controller minimizes the vehicle's predicted lateral deviation and heading error with respect to the desired path at a preview point, and gains of the controller are scheduled with respect to vehicle speed.

New corrosion resistant coatings for brake tubing have been evaluated by use of the accelerated vehicle corrosion test and the trailer corrosion test. These tests appear useful for comparing the end point perforation resistance of the tubing coating combination and for comparing the corrosion and paint adhesion properties of the coatings, respectively. The paper discusses the procedure and results of the accelerated vehicle corrosion test as well as burst pressure tests after accelerated vehicle corrosion testing.