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It is well known that the ride quality of trucks is much harsher than that of automobiles. Additionally, truck drivers typically drive trucks for much longer duration than automobile drivers. These two factors contribute to the fatigue that a truck driver typically experiences during long haul deliveries. Fatigue reduces driver alertness and increases reaction times, increasing the possibility of an accident. One may conclude that better ride quality contributes to safer operation. The secondary suspensions of a tractor have been an area of particular interest because of the considerable ride comfort improvements they provide. A gap exists in the current engineering domain of an easily configurable high fidelity low computational cost simulation tool to analyze the ride of a tractor semi-trailer. For a preliminary design study, a 15 d.o.f. model of the tractor semi-trailer was developed to simulate in the Matlab/Simulink environment.

In this paper, a soft computing approach to a model-free vehicle stability control (VSC) algorithm is presented. The objective is to create a fuzzy inference system (FIS) that is robust enough to operate in a multitude of vehicle conditions (load, tire wear, alignment), and road conditions while at the same time providing optimal vehicle stability by detecting and minimizing loss of traction. In this approach, an adaptive neuro-fuzzy inference system (ANFIS) is generated using previously collected data to train and optimize the performance of the fuzzy logic VSC algorithm. This paper outlines the FIS detection algorithm and its benefits over a model-based approach. The performance of the FIS-based VSC is evaluated via a co-simulation of MATLAB/Simulink and CarSim model of the vehicle under various road and load conditions. The results showed that the proposed algorithm is capable of accurately indicating unstable vehicle behavior for two different types of vehicles (SUV and Sedan).

This paper presents the application of a proposed fuzzy inference system as part of a stability control design scheme implemented with active steering actuator sets. The fuzzy inference system is used to detect the level of overseer/understeer at the high level and a speed-adaptive activation module determines whether an active front steering, active rear steering, or active 4 wheel steering is suited to improve vehicle handling stability. The resulting model-free system is capable of minimizing the amount of model calibration during the vehicle stability control development process as well as improving vehicle performance and stability over a wide range of vehicle and road conditions. A simulation study will be presented that evaluates the proposed scheme and compares the effectiveness of active front steer (AFS) and active rear steer (ARS) in enhancing the vehicle performance. Both time and frequency domain results are presented.

Electric vehicles are receiving considerable attention because they offer a more efficient and sustainable transportation alternative compared to conventional fossil-fuel powered vehicles. Since the battery pack represents the primary energy storage component in an electric vehicle powertrain, it requires accurate monitoring and control. In order to effectively estimate the battery pack critical parameters such as the battery state of charge (SOC), state of health (SOH), and remaining capacity, a high-fidelity battery model is needed as part of a robust SOC estimation strategy. As the battery degrades, model parameters significantly change, and this model needs to account for all operating conditions throughout the battery's lifespan. For effective battery management system design, it is critical that the physical model adapts to parameter changes due to aging.

The components in a hybrid electric vehicle (HEV) powertrain include the battery pack, an internal combustion engine, and the electric machines such as motors and possibly a generator. These components generate a considerable amount of heat during driving cycles. A robust thermal management system with advanced controller, designed for temperature tracking, is required for vehicle safety and energy efficiency. In this study, a hybridized mid-size truck for military application is investigated. The paper examines the integration of advanced control algorithms to the cooling system featuring an electric-mechanical compressor, coolant pump and radiator fans. Mathematical models are developed to numerically describe the thermal behavior of these powertrain elements. A series of controllers are designed to effectively manage the battery pack, electric motors, and the internal combustion engine temperatures.

Driver modeling is essential to both vehicle design and control unit development. It can improve the understanding of human driving behavior and decrease the cost and risk of vehicle system verification and validation. In this paper, three driver models were implemented to simulate the behavior of drivers subject to a run-off-road recovery event. Target path planning, pursuit behavior, compensate behavior, physical limitations, and neuromuscular modeling were taken into consideration in the feedforward/feedback driver model. A transfer function driver model and a cost function based driver model from a popular vehicle simulation software were also simulated and a comparison of these three models was made. The feedforward/feedback driver model exhibited the best balance of performance with smallest overshoot (0.226m), medium settling time (1.20s) and recovery time (4.30s).

Composites are now extensively used in applications where outstanding mechanical properties are necessary in combination with weight savings, due to their highly tunable microstructure and mechanical properties. These properties present great potential for part integration, which results in lower manufacturing costs and faster time to market. Composites also have a high level of styling flexibility in terms of deep drawn panel, which goes beyond what can be achieved with metal stampings. The so-called multifunctional or smart composites provide significant benefits to the vehicles as compared to the traditional materials that only have monotonic properties.

Design of Automotive Composites reports that successful designs of automotive composites occurred recently in this arena. The chapters consist of eleven technical papers selected from the Automotive Composites and other relevant sessions that the editors have been organizing for the SAE International World Congress over the past five years. The book is divided into four sections: o Body Structures o Powertrain Components o Suspension Components o Electrical and Alternative Vehicle Components The composite design examples presented in Design of Automotive Composites come from the major OEMs and top-tier suppliers and are most relevant to the automotive materials challenges currently faced by the industry. Many of the innovative ideas have already been implemented on existing or new model vehicles, although a great deal of innovation is still in the works.

Motor vehicle crashes involving novice drivers are significantly higher than matured driver incidents as reported by the National Highway Traffic Safety Administration Fatality Analysis Reporting System (NHTSA-FARS). Researchers around the world and the United States are focused on how to decrease crashes for this driver demographic. Novice drivers usually complete driver education classes as a pre-requisite for full licensure to improve overall knowledge and safety. However, compiled statistics still indicate a need for more in-depth training after full licensure. An opportunity exists to supplement in-vehicle driving with focused learning modules using automotive simulators. In this paper, a training program for “Following Etiquette” and “Situational Awareness” was developed to introduce these key driving techniques and to complete a feasibility study using a driving simulator as the training tool.

Exhaust gas turbo-charging helps exploit the improved fuel efficiency of downsized engines by increasing the possible power density from these engines. However, turbo-charged engines exhibit poor transient performance, especially when accelerating from low speeds. In addition, during low-load operating regimes, when the exhaust gas is diverted past the turbine with a waste-gate or pushed through restricted vanes in a variable geometry turbine, there are lost opportunities for recovering energy from the enthalpy of the exhaust gas. Similar limitations can also be identified with mechanical supercharging systems. This paper proposes an electrical supercharging and turbo-generation system that overcomes some of these limitations. The system decouples the activation of the air compression and exhaust-energy recovery functions using a dedicated electrical energy storage buffer. Its main attributes fast speed of response to load changes and flexibility of control.

To facilitate the design of a non-pneumatic tire for NASA's new Moon mission, the authors used the Finite Element Method (FEM) to investigate the interaction between soil and non-pneumatic tire made of different cellular shear bands. Cellular shear bands, made of an aluminum alloy (AL7075-T6), are designed to have the same effective shear modulus of 6.5E+6 Pa, which is the shear modulus of an elastomer. The Lebanon sand of New Hampshire is used in the model. This sand has a complete set of material properties in the literature and Drucker-Prager/Cap plasticity constitutive law with hardening is employed to model the sand. The tires are treated as deformable bodies, and the authors used the penalty contact algorithm to model the tangential behavior of the contact. The friction between tire and sand is considered by using Coulomb's law. Numerical results show deformation of sand and tire.

This research examines a Discrete Element Method (DEM) for modeling the behavior of sand under various loading conditions as a critical first step in developing computational tools to aid in designing new sand-tire interaction systems for improved traction and mobility. Sand as a material is challenging to model computationally due to its unusual behavior: sometimes resembling a fluid and sometimes behaving more like a solid, yet never exactly replicating either. This behavior arises from the particulate nature of sand which, in contrast to the systems typically modeled in continuum mechanics, is not readily represented by continuum models. In sand, elements (i.e. particles) do not have permanent associations with neighboring elements as they do in most continua, but rather are free to migrate anywhere in the domain according to their interactions with other elements.

The number of control actuators available on spark-ignition engines is rapidly increasing to meet demand for improved fuel economy and reduced exhaust emissions. The added complexity greatly complicates control strategy development because there can be a wide range of potential actuator settings at each engine operating condition, and map-based actuator calibration becomes challenging as the number of control degrees of freedom expand significantly. Many engine actuators, such as variable valve actuation and flow control valves, directly influence in-cylinder combustion through changes in gas exchange, mixture preparation, and charge motion. The addition of these types of actuators makes it difficult to predict the influences of individual actuator positioning on in-cylinder combustion without substantial experimental complexity.

This paper discusses the development of several models and accompanying results for the simulation of the longitudinal and vertical dynamics of a front wheel drive drag car. Models developed include provisions for wheelie bar, chassis flexibility, and anti-squat geometry. The simulation computes quarter-mile times and speeds for various combinations of input parameters. It allows for the analysis of the various factors that affect steady state axle loads and dynamic load transfer, their effects on traction, and the resulting quarter-mile times. Results of case studies examine specific vehicle components and parameters and their effects on performance. These include the wheelie bar, wheel rates, anti-squat properties, and chassis flexibility.

Many of the suspension adjustments that are made to improve the handling of asymmetric cars racing on banked oval tracks are not intuitively obvious to the engineer who is used to thinking of symmetric cars on relatively flat roads. This paper investigates the effects of typical suspension adjustments on the steady state handling of a Winston Cup race car. A relatively simple nonlinear car model is combined with a sophisticated tire model to predict steady-state handling on a banked track. The concept of dynamic wedge is explained, and its effects on handling of asymmetric race cars on banked ovals are examined. Results are presented that show the sensitivity of the handling to changes in various suspension characteristics.

Using a previously validated and documented CFD methodology, this research simulated the flow field in the intake region (inlet duct, plenum, ports, valves, and cylinder) involving the four cylinders (#1, #3, #4, #6) of a straight-six IC engine. Each cylinder was studied with its intake valves set at high, medium and low valve lifts. All twelve viscous 3-D turbulent flow simulation models had high density, high quality computational grids and complete domains. Extremely fine grid density were applied for every simulation up to 1,000,000 finite volume cells. Results for all the cases presented here were declared “fully converged” and “grid independent”. The relative magnitude of total pressure losses in the entire intake region and loss mechanisms were documented here. It was found that the total pressure losses were caused by a number of flow mechanisms.

A computational methodology has been developed for loss prediction in intake regions of internal combustion engines. The methodology consists of a hierarchy of four major tasks: (1) proper computational modeling of flow physics; (2) exact geometry and high quality and generation; (3) discretization schemes for low numerical viscosity; and (4) higher order turbulence modeling. Only when these four tasks are dealt with properly will a computational simulation yield consistently accurate results. This methodology, which is has been successfully tested and validated against benchmark quality data for a wide variety of complex 2-D and 3-D laminar and turbulent flow situations, is applied here to a loss prediction problem from industry. Total pressure losses in the intake region (inlet duct, manifold, plenum, ports, valves, and cylinder) of a Caterpillar diesel engine are predicted computationally and compared to experimental data.

The control of body roll on passenger vehicles can be used as a tool for controlling the “weight shift” that occurs during maneuvering. Distribution of load to the tires will determine the ability of each tire to generate lateral forces required for the maneuver and thus will significantly affect handling. In this investigation, the effects on weight shift and hence, on handling, of total roll stiffness, front to rear roll stiffness distribution, total roll damping, and roll damping distribution were examined. These results were then used to guide the development and analysis of several roll control algorithms. The results of the investigation indicate that roll control can be effective in improving handling and stability. However, simulation of the control algorithms showed that the controllers must be specifically tuned for the vehicle in which they are to be used.

Track testing of race cars is expensive and racing series typically limit the amount of testing that can be done on circuit tracks. Because of this, we saw the need to develop a computer model that could simulate a car on a track with any specified surface roughness and with aerodynamic loading acting on the vehicle. This model allows an analysis of the effect of aerodynamic loading on the vertical dynamic response of the vehicle. Vehicle parameters specific to an IMSA GTP car including aerodynamic data from wind tunnel testing and nonlinear shock characteristics were used in this study. Simulations were run for various speeds and ride height configurations and it was found that very small changes in the static settings of the front and rear ride heights can lead to large differences in the resulting ride heights at speed. This can be attributed to the variations in the nonlinear aerodynamic loading as the ride height and speed of the vehicle change.

A simulation of the vertical response of a nonlinear 1/4 car model consisting of a sprung and an unsprung mass was developed. It is being used for preliminary evaluation of various suspension configurations and control algorithms. Nonlinearities include hysteretic shock damping and switchable damping characteristics. Road inputs include discrete events such as bumps and potholes as well as randomly irregular roads having specified power spectral densities (PSDs). Fast Fourier transform data analysis procedures are used to process data from the simulation to obtain PSDs, rms values, and histograms of various response quantities. To aid in assessing ride comfort, the 1/3 octave band rms acceleration of the sprung mass is calculated and compared with specifications suggested by the International Standards Organization (ISO). Cross plots of the rms values of acceleration, suspension travel, and the force of the road on the tire are used to compare the performance of various suspensions.