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This research compares the responses of a vehicle modeled in the 3D vehicle simulation program SIMON in the HVE simulation operating system against instrumented responses of a 3-axle tractor, 2-axle semi-trailer combination. The instrumented tests were previously described in SAE 2001-01-0139 and SAE 2003-01-1324 as part of a continuous research effort in the area of vehicle dynamics undertaken at the Vehicle Research and Test Center (VRTC). The vehicle inertial and mechanical parameters were measured at the University of Michigan Transportation Research Institute (UMTRI). The tire data was provided by Smithers Scientific Services, Inc. and UMTRI. The series of tests discussed herein compares the modeled and instrumented vehicle responses during quasi-steady state, steady state and transient handling maneuvers, producing lateral accelerations ranging nominally from 0.05 to 0.5 G's.

Air flow in the underhood area is the primary source of engine cooling. A quick look at the vehicle underhood reveals exceptionally complex geometry. In addition to the engine, there are fans, radiator, condenser, other heat exchangers and components. The air flow needs to have adequate access to all relevant parts that require cooling. Due to complex geometry, the task to ensure sufficient air cooling is not a simple one. The air flow entering from the front grille is affected by many components on its path through the underhood. Even small geometry details affect the flow direction and can easily cause recirculation regions which reduce the cooling efficiency. Therefore, air cooling flow analysis requires detailed treatment of the underhood geometry and at the same time accurate air flow modeling. Recent advances in the lattice-Boltzmann equation (LBE) modeling are allowing both.

In this paper, we explain the process of designing a fuzzy based controller which can be installed in a vehicle. This controller uses sensors and actuators to coordinate suspension, brakes and steering system in critical situations to help a driver maintain the kinetic balance of the vehicle. An advantage of this controller is that it doesn't interfere with the driver's habit in vehicle control and it resumes functioning only in critical moments. Using various actuators and sensors, we introduce a new approach to detect instability and the turnover threshold. This makes the proposed fuzzy analyzer a novel one.

Two simulation analysis case studies for optimization of disc brake assembly level performance and component structural strength using CAE tools were discussed. The first case study discussed was about disc brake assembly level simulation studies to optimize brake pads contact pressures in order to achieve uniform brake friction pad wear during operation, and optimize the guide pin reaction loads. In the second case study, structural optimization of brake torque plate using CAE tools was discussed. The CAE results were validated with the component testing.

To validate the integrity of a commercial vehicle's exhaust system's structural design is a challenging job. An integrated approach to use both simulation/modeling and hardware testing must be employed to reduce product development cost. In addition to the considerations of the geometry and configuration specs of 70-90 parts and joints as well as material's thermal and mechanical property data in model development, representative loading must be used. For base excitation type of loading, such as the one experienced by the vehicle's exhaust system, one must decide whether to conduct the time domain transient analysis or frequency domain random vibration analysis. Although both methods are well known, few discussions can be found in the literature regarding their effective use in the framework of product design and development. Based on our study, the random vibration method should be used first for identifying high stress locations in the system and for design optimization.

Construction of a transient model for a Class 8 tractor-trailer negotiating mountain terrain is presented. Four basic brake models for free and forced cooling (GSRS, UMTRI, Limpert, and HVE Brake Designer®) are converted to consistent units. The units have been reduced to those accepted variables in the thermodynamic/heat transfer literature (hc, A, cp, M), thereby facilitating model comparison and coefficient selection from the published literature. The data has been compared to real test published data. The effect of varying the desired vehicle speed, vehicle weight, number of adjusted brakes, and slope magnitude on brake drum temperatures is explored.

Chassis dynamometer testing of two 60 foot articulated transit busses, one conventional and one hybrid, was conducted at the National Renewable Energy Laboratory's, ReFUEL facility. Both test vehicles were 2004 New Flyer busses powered by Caterpillar C9 8.8L engines, with the hybrid vehicle incorporating a GM-Allison advanced hybrid electric drivetrain. Both vehicles also incorporated an oxidizing diesel particulate filter. The fuel economy and emissions benefits of the hybrid vehicle were evaluated over four driving cycles; Central Business District (CBD), Orange County (OCTA), Manhattan (MAN) and a custom test cycle developed from in-use data of the King County Metro (KCM) fleet operation. The hybrid vehicle demonstrated the highest improvement in fuel economy (mpg basis) over the low speed, heavy stop-and-go driving conditions of the Manhattan test cycle (74.6%) followed by the OCTA (50.6%), CBD (48.3%) and KCM (30.3%).

Faulty brakes on heavy trucks continue to be a leading cause of vehicle-based Out-of-Service (OOS) violation citations, and are a contributing factor in many heavy truck crashes. In order to allow the driver and fleet manager to quickly diagnose one functional aspect of the vehicle's braking system, an electronic brake stroke sensor has been developed. This paper discusses the development and operation of the digital brake stroke sensor along with initial in-lab test results.

This paper deals with the study of experimental investigations on Homogenous Charge Diesel Combustion (HCDC) system. The study had been carried out in a four-stroke air- cooled single cylinder diesel engine of rated power 4.4 kW thereby converting a ceramic-coated diesel engine into HCDC mode by using a port fuel injector to create a homogenous charge. Electronic fuel injection circuit was developed to control the injection timing and duration of the premixed charge. Gasoline was premixed and port injected before ignition whereas the diesel fuel was injected by the conventional injector directly into the cylinder. Port injected gasoline and direct injected diesel were tested for various proportions to optimize the operating range without varying any existing engine parameters (unmodified engine). From the study conducted, it was found that oxides of nitrogen (NOx) and smoke emissions were reduced simultaneously at 40% premixed charge.

Research has shown that the emission characteristics of Biodiesels are different compared to petroleum derived diesel. Though overall emissions of most of the Biodiesels are less than that of diesel, it has been found that many bio-esters have higher NOX emissions. This necessitates the testing of the various blends and selection of the Biodiesel that has acceptable emission characteristics especially with respect to NOX emissions. Due to the sheer number of variations, it becomes very tedious to manually test for every blend and for every Biodiesel. This paper introduces an elegant method of the above required analysis by establishing an Artificial Neural Network (ANN) that is trained to predict engine emission based on fuel properties. Emission data is collected by testing a CI engine under different loads for series of blends with diesel of various Biodiesels and is used to train the network.

Due to higher diesel fuel prices, operators of heavy trucks, especially large fleets, are looking for ways to increase fuel economy. One way to increase fuel economy is to reduce the “parasitic” horsepower losses on the engine. Today's mechanically driven cooling fans are a large draw on the engine horsepower. The function of the Thermal Kits is to provide auxiliary engine cooling and air conditioning condenser cooling with electric fans and electric water pumps. This paper details the application of Thermal Kits to various heavy duty truck applications, including control system development and vehicle integration. Fuel economy improvements from these Kits in various applications are currently being independently validated and should be available by the 2006 Commercial Vehicle Conference.

This paper describes an analytical process for the design of a brake shoe assembly that consists of the linings, shoe table, webs, and rivets. One fundamental performance requirement for the brake shoe assembly is that the linings will not lose clamp force within the desired service life. Key elements of the analytical process involved developing an FEA model with given loading conditions and developing a mathematical model to study the influence parameters of the forces acting on the lining.

The CFD tools in aerodynamic design process have been commonly used in aerospace industry in last three decades. Although there are many CFD software algorithms developed for aerodynamic applications, the nature of a complex, three-dimensional geometry in incompressible highly separated, viscous flow made computational simulation of ground vehicle aerodynamics more difficult than aerospace applications. However, recent developments in computational hardware and software industry enabled many new engineering applications on computational environment. Traditional production process has largely influenced by computational design, analysis, manufacturing and visualization. Different aspects of linking advanced computational tools and aerodynamic vehicle design challenges are discussed in the present work. Key technologies like parallel computation, turbulence modeling and CFD/wind tunnel compatibility issues are presented.

Carbon particles have the capability to be electrically charged. A very high static electrical field attracts particles through Coulomb forces in that they touch statistically the high voltage electrode of a capacitor incorporated into the main exhaust gas flow. By touching the electrode they are charged. Having the same polarity they are repelled and move to the grounded electrode where they are discharged. This procedure produces an electrical current. The RMS value of this amplified signal represents the particle mass. The dependency on the gas flow speed is corrected by a mathematical procedure incorporating the intake parameters of the engine. For high accurate measurements a low constant exhaust gas speed is necessary achieved by a pump sucking the gas through a bypass. To avoid interference from capacitor blade vibrations and gas flow oscillations inside the exhaust silencers a low-pass filter with a cut-off frequency of 2 Hz e.g. is necessary.

One of the key technologies of automotive active safety systems is to calculate the wheel speed and wheel angular acceleration or deceleration. Obtaining an accurate control quantity is the prerequisite for active safety systems no matter what control logics are used to realize the control function. This paper puts forward a new wheel speed processing algorithm. This method was simulated in MATLAB \ Simulink. Then it was tested in a certain type of vehicle of FAW by applying dSPACE RCP. It proves that this algorithm assures the precision at high and low speed and the real-time performance at low speed.

In efforts to prevent airflow noise and conserve heated and/or cooled air, express bus design has favored fixed windows, double glasses and closed structures with lower rates of ventilation. However, because there are many passengers in an express bus at the same time, offensive odor, carbon dioxide and other contaminants may accumulate in the bus's indoor. If sufficient amounts of ambient air are not brought into or distributed throughout the passenger compartment of the bus, in-bus air problems may result. An air ventilating system of the express bus that is properly designed, and that has a good performance of natural ventilation, can promote the air quality of the passenger compartment and the comfort of passengers. In order to design an effective ventilating system of the express buses, some design factors such as air inlet/outlet positions, air distribution, proportion of ambient air, and airflow control are considered computationally and experimentally in this work.

A hybrid search optimization is presented in order to optimize hybrid laminated fibrous composite E-springs for vehicle suspension systems. This optimization is conducted with both of the geometrical configuration and laminate structure of the E-spring. A genetic algorithm along with a hill-climbing random-walk approach are used through a developed NURBS-based technique in order to conduct this optimization. A mathematical-modeling-based mid-ware technology is introduced in order to fully automate the optimization process through linking the run engines of mathematical modeling and finite element analysis from within the mathematical modeling engine. A hybrid approach of the inter-laminar shear stress and Tsai-Wu criteria is first implemented in order to identify failure indices of the resulting optimum shape and laminate structure.

Non-round substrates are often applied in exhaust applications with limited packaging space, including commercial vehicles, and the shape of their metallic shells are often designed to be similar, but enlarged to accommodate the layer of support mat. This gap is often planned to be constant around its perimeter, but measured data indicates this rarely occurs. This study evaluates a particular oval converter mount design and applies a unique method to couple finite-element modeling with support mat response characteristics to predict non-round shell shapes, planning for uneven gap distributions. This method allows for increased awareness of acceptable mount designs, as well as improved manufacturing and durability performance, which becomes even more important within commercial vehicle design applications, subject to larger substrate sizes, increased backpressures, and extended mileage requirements.

Applying FEA optimization analysis in our utility vehicle and golf car virtual prototyping has proven very useful in accelerating time to market for new product, and reducing R&D cost. This article looks at reducing manufacturing costs, correlating FEA model with field test data and diagnosing field failure root causes. The cost reduction application uses topological analysis for preliminary design and uses Goal Driven Optimization with six independent factors corresponding to two separate loads for final dimension determination. A parametric model is the basic requirement for DOE. The model can be imported from CAD directly, and it can also be created after non-parametric geometry or the initial FEA file is imported.

The National Research Council of Canada (NRC) has completed the second round of full-scale wind tunnel tests on Class-8 tractor-trailer combinations. The primary intent of the program is to effect a reduction in greenhouse-gas emissions by reducing the fuel consumption of trucks through aerodynamic drag reduction. Add-on aerodynamic components developed at the NRC several decades ago have become important contenders for drag reduction. This program has encouraged the commercialization of these technologies and this round of tests evaluated the first commercial products. Three primary devices have been evaluated, with the combination able to reduce fuel consumption by approximately 6,667 liters (1,761 US gal) annually, based on 130,000 km (81,000 miles) traveled per tractor at a speed of 100 km/hr (62 mi/hr).