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Virtual proving ground (VPG) simulations have been popular with passenger vehicles. VPG uses LS-DYNA based non-linear contact Finite Element analysis (FEA) to estimate fully analytical road loads and to predict structural components durability with PG road surfaces and tire represented as Finite elements. Heavy vehicle industry has not used these tools extensively in the past due to the complexity of heavy vehicle systems and especially due to the higher number of tires in the vehicle compared to the passenger car. The higher number tires in the heavy vehicle requires more computational analysis duration compared to the passenger car. However due to the recent advancements in computer hardware, virtual proving ground simulations can be used for heavy vehicles. In this study we have used virtual proving ground based simulation studies to predict the durability performance of a trailer suspension frame.

Reduction of alternator noise has become an increasingly important task in automotive industry as requirements for passenger compartment comfort increase, and other components such as the engine, exhaust system, etc. are made quieter. However, the aim of this study is to identify the noise sources of a numbers of alternator bands and to develop design guidelines to reduce the overall noise levels sacrificing the specified performance. With these guidelines, design engineers can reduce alternator noise effectively. To identify mechanical, aerodynamic and electromagnetic noise generation mechanisms, the alternator was reconfigured in many different ways, so as to separate each individual noise source. Noise generated by each configuration running at different speeds was measured, and its characteristics were analyzed. A special test stand was designed and fabricated, and tests were conducted in the automotive laboratory.

This paper studies the proportional directional control valves design influence on the energetic behavior of a mid-power compact excavator. In particular, with reference to the hydraulic circuit actuating the primary workgroup, in the paper the hydraulic power metering performed with the boom cylinder proportional control valve is studied, and some design solution useful in reducing both the hydraulic power dissipation, and the power absorption from the machinery prime mover are highlighted. The analysis, experimentally performed for different operating conditions, is carried out highlighting the influence of a metering configuration both on the supply pressure modulation and on the flow-rate supplied to the actuator.

In an effort to reduce the dry stopping distance required for heavy trucks, it is imperative to increase the effectiveness of the foundation brake systems. Where brakes are torque limited, increasing the brake output can be obtained by increasing brake size, chamber size, slack length, and friction of the braking materials. Looking just at the aspect of foundation brakes, the majority of current tractor and trailer brakes are of the S-Cam and Drum type. Two commercially available alternatives that produce higher output are Air Disc brakes and larger sized S-Cam brakes. Using one type, or a combination of these brakes (discs and drums on different axles) warrants a comparative study. The goal is to improve the effectiveness of the brake system, while maintaining or improving upon vehicle stability during braking. NHTSA's Vehicle Research and Test Center recently completed a brake test study of the effectiveness and stability characteristics of tractor and trailer combinations.

The hybrid electric vehicle is currently changing the automotive market at an impressive rate. While not as highly publicized, the transit bus market is being transformed at an equal rate. As these markets move forward, the school bus market remains largely unchanged. As an unchanged market, there is still the opportunity to optimize a hybrid vehicle platform for school buses. This study begins the modeling process of an existing class C school bus and investigates the potential that both series and parallel hybrids hold to reduce fuel consumption and emissions for a school bus. The primary focus of this study is to investigate the potential benefits of adding an electricity grid interconnection to hybrid electric school buses, allowing them to add to the hybrid potential with a pre-charged battery pack from the electric utility grid. These vehicles are known as plug-in hybrids.

A Decision Network is an explicit model of the Thinking Breakdown Structure of any complex scientific, engineering, or societal challenge. Each node in the Decision Network represents a fundamental question that must be answered, i.e. a choice that demands a solution. A Decision Network provides an integrated Decision Management framework for any Systems Engineering effort that links business, technology and design choices. Effective Decision Management is the key to Systems Engineering success. This paper will provide an overview of a decision-centric approach to Systems Engineering built around Decision Networks. Lessons learned through the use of Decision Networks in other industries will be extrapolated for use in vehicle Systems Engineering.

This paper describes the implementation effort behind adding a pair of suspension links between the axle and frame of a light truck with a Hotchkiss-type suspension. These links, referred to as anti-windup bars (or traction bars), were introduced into an existing system to improve NVH performance; however, doing so required modifications to maintain other vehicle attributes, including vehicle safety and durability life. The authors address the management of these attributes and related design decisions for the components involved, focusing on the conflicting requirements involved. Physical vehicle testing, using design revisions recommended by Finite Element (FE) simulations, was performed to confirm component performance and related system behavior. Test results suggested improvements to the FE models that were required to more closely approximate the vehicle's behavior.

In this paper a lumped parameters numerical model is reviewed to study the meshing process of external gear pumps and motors, with the aim of highlighting the influence of some geometrical design parameters and operating conditions on inter-teeth volumes pressures. The inter-teeth space is modeled adopting a two-volume approach, properly tailored both for the pump and for the motor units behavior description. In both cases, the communications between the interconnected inter-teeth volumes and the high and low pressure ports are sketched as variable equivalent turbulent restrictors; flow areas have been determined as functions of the gears and of the meshing grooves main design parameters. The inter-teeth pressures, and the leakage flows, are calculated solving the incompressible and isothermal continuity equation, contemporarily applied to both volumes and properly combined with the classical turbulent orifice equation.

This paper discusses implementing 120V AC on trucks. We will discuss the following topics: A. A brief history of AC generation B. AC power requirements on trucks C. Issues and concerns D. Summary and conclusion

A revolution in mobile hydraulic equipment is occurring. Conventional hydraulic spool valves with hydromechanical pressure compensators are being replaced by valve assemblies with four valve independent metering with electronically-controlled pressure compensation. In the system described here, two of the four independent valves are active during metering. This new topology offers significant advantages due to the two degrees of freedom provided. One of these degrees of freedom used to control velocity is more fully described in a related paper. In this paper, it is shown how the second degree of freedom can be used to control pressure in an actuator workport or minimize velocity errors due to valve coefficient errors. Workport pressure control can be used to limit maximum or minimum workport pressures (e.g. prevent cavitation). Given certain criteria, an optimal solution can be obtained.

This paper discusses a statistical approach to the analysis of power consumption in Class 8 Sleeper Trucks. We will also make recommendations for the electrical design of Class 8 truck. The paper discusses past electrical devices, why device use has increased, and how electrical system design has changed to keep up with truck evolution. We will analyze the electrical loads on the vehicle. This will include a list of cab and sleeper loads common to heavy trucks, current draws, and the advantages this analysis will give to the electrical designers. The analysis also provides peak and average electrical consumption for typical trucks, which helps in optimizing the associated electrical design of a truck power system. Six Sigma is used to analyze the electrical load data. Six Sigma is a systematic, data driven approach to statistically describe a process. Our process of designing an electrical system will greatly benefit from the use of this tool.

The sloshing behavior of a liquid cargo is an issue that needs to be taken into account when evaluating the dynamic performance of tankers. In general, hazardous liquid materials require a free volume into the tank to absorb thermal expansion changes; therefore, tank has to be filled partially. Under that condition, sloshing is produced at the liquid surface which interacts with container walls generating forces that affect the vehicle’s behavior. In this work, results obtained from experimental tests carried out in a scaled elliptical-transversal-section tank for different filling levels, baffles’ geometries, and baffles’ arrays are presented. Tank is instrumented so that longitudinal forces due to sloshing can be measured when tank is suddenly stopped. The analysis of the results allows identifying the best baffle configuration to be applied in order to attenuate the longitudinal sloshing generated when the vehicle is moving on highways.

Harmonization of systems and components leads to platform strategies within the truck industry as already known from the automotive industry. With respect to the Electrical- and Electronic Distribution System (EEDS) the investigations are focusing on common electrical systems and components, i.e. ECUs, sensors, actors, switches and connectors, to be used as carry-over parts in order to increase the volume and the quality and to reduce the cost. This investigation shows the different aspects and requirements on electronics and the Electrical Distribution System (EDS) within a communized electrical power supply. Finally a recommendation for best practices based on a currently available technology is given.

In this study, the air suspension is newly applied to the engine mounting layout for getting the significant vibration isolation effect. In this case, the genetic algorithm so called GA is also applied for the optimization of many parameters, calculations of stiffness matrix and inverse stiffness matrix to prevent the coupled vibration of lateral and rolling modes and to obtain the displacement of each mounting point. As a result, inexperienced engineers can easily obtain the optimum engine mounting layout in a minute. By the confirmation test of FEM, the engine lateral vibration level at 25Hz dropped below 1/10 and its effect was significant.

Dual clutch based transmissions (DCT) have been developed for passenger vehicles in Europe. Compared to a single clutch based transmission (SCT), DCT eliminates torque interrupts during gear-shifting so that the vehicles can run as smooth as one using an automatic transmission (AT). Traditionally AT needs to use torque converters to transmit engine torque to drivelines. However, a torque converter is complicated and expensive, and offers lower driveline efficiency than SCT and DCT. DCT technology is a cost-effective avenue to achieve smooth shifting while taking advantage of the some beneficial features of both AT and SCT. This paper presents the results of an analysis of the application of DCT on medium duty (MD) trucks. First, we set up a 6-speed DCT with two groups of three gear ratios in correspondence to two ceramic dry clutches. Clutch dampers are included in the DCT model. For simplicity but without loss of generality, the synchronizers are not included for this study.

Real-time theory is introduced to analyze reliability and robustness for ECU (Electronically Controlled Unit) of vehicle AMT (Automatic Mechanical Transmission). Real time analysis architecture is proposed. Analysis and simulation for the four working stages of AMT are illustrated. The results show, the real time system model with 9 tasks working on 4 processors is reasonable, and the designed Blended Timer-Triggered Scheduler is feasible as well as robust, which provide the system more extendibility and reliability.

Carbon based friction materials continue to gain increasing acceptance in many friction applications. One unique class of carbon based friction materials is Chemical Vapor Deposited carbon fabric (CVD Fabric™) Since 1991, CVD Fabric™ has been used in production automotive wet friction applications including limited slip differentials and heavy and medium duty truck transmission synchronizers. It offers stable friction levels, low wear rates and is readily wetted by transmission oils. Because CVD Fabric does not soften with temperature and is unaffected by solvents, this high energy absorption, high abuse tolerant material may provide significant performance advantages in off-highway wet brake and clutch applications. This paper will explore the Physical, mechanical and tribological properties of CVD Fabric wet friction materials.

The on-road lateral stability of an articulated steer vehicle is investigated for both small and high deviations. First, for small deviations, a linear model of the vehicle is devised and analyzed. This planar model is generated based on some simplifying assumptions. For instance, the equations describing the tire forces and moments are linearized, and the tire rolling resistance is neglected. A linear stability analysis of the straight line motion of the vehicle with constant forward speed is conducted by using this simplified model for different values of the torsional stiffness and damping at the articulation joint. To investigate the lateral stability of the vehicle at higher deviations, the motion of a virtual prototype of the vehicle in ADAMS/View is simulated for different conditions. Finally, the results from the simulations and the linear stability analyses are compared.

The present article looks into possibilities for using drive axle semiactive suspension systems of a tractor in a tractor-semitrailer combination. The problem has been studied by means of computer-aided simulation, with ADAMS/Car MSC software. The shock absorbers of the semiactive suspension are provided with closed-loop preview control. Thus, the steering front axle of the tractor functions as a sensor to register road irregularities that the wheels of the drive axle should overcome. There has been suggested a simplified control logic for the semiactive suspension, being based on the outcomes of the study of the closed-loop preview control algorithm. When used for the drive axle of the tractor in the tractor-trailer combination, the semiactive suspension has been demonstrated to reduce the coefficient of variation of dynamic vertical forces on road pavement by 5,5 to 7%, in comparison with the conventional suspension types.

Transient fluid slosh within a partly-filled tank could impose high stresses on the tank structure and affect the directional performance in an adverse manner. A three-dimensional nonlinear model of a partly filled circular cylindrical tank with and without baffles is formulated and analyzed to derive the pressure distribution over the wetted tank surface. The baffles and end caps are modeled with curved shapes in accordance with the current standard. The analyses are performed for 40% and 60% fill volumes and different types of baffles, including single-nozzle and multiple-orifice baffles, using the FLUENT software under time varying acceleration fields representing simultaneous braking and turning maneuvers. The pressure data are further analyzed to evaluate steady-state and transient slosh forces, load shifts along the longitudinal and lateral axes, and the roll, pitch and yaw moments imposed on the tank structure.