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Multidimensional numerical simulations are performed to predict and optimize engine performance of a spark-ignited natural gas engine. The effects of swirl and combustion chamber geometry on in-cylinder turbulence intensity, burning rate and heat transfer are investigated using the KIVA multidimensional engine simulation computer code. The original combustion model in the KIVA code has been replaced by a model which was recently developed to predict natural gas turbulent combustion under engine-like conditions. Measurements from a constant volume combustion chamber and engine test data have been used to calibrate the combustion model. With the numerical results from KIVA code engine thermal efficiencies were predicted by the thermodynamics based WAVE code. The numerical results suggest alternative combustion chamber designs and an optimum swirl range for increasing engine thermal efficiency.

Welding residual stress is one of the primary factors responsible for cracking at the access hole interface between the flange and web plate of welded heavy W-shapes. During multi-pass welding, cracks can be found in either the flange plate or the web plate, depending upon welding sequence, joint details and access hole size. In this study, an integrated numerical and experimental investigation was conducted to evaluate the effects of welding parameters and joint geometry on the magnitude and distribution of residual stresses in thick-section butt joints. The results provide guidelines for improved design for welding of heavy W-shapes.

The Maryland Mass Transit Administration conducted an LNG transit bus demonstration in Baltimore, Maryland. A refueling facility was constructed and maintenance facilities were modified to provide support for the demonstration. During the demonstration operational data were collected on the buses and facilities. Problems encountered with the vehicle LNG fuel systems are reviewed and discussed. This paper summarizes the findings and operation of the LNG fleet during the demonstration and projects future LNG vehicle and operational costs.

Ford Motor Company has introduced its dedicated Natural Gas Vehicle (NGV) trucks as mid-year 1997 offerings to complement its dedicated Crown Victoria and bi-fuel Qualified Vehicle Modifier (QVM) product line-up. The 5.4L F-250 full-size pick-up truck and the 5.4L E-250/E-350 full-size vans are production vehicles maintaining Original Equipment Manufacturer (OEM) quality and warranty while complying with all applicable corporate, federal and state requirements. Both trucks are the first OEM vehicles to certify at the Super Ultra Low Emission Vehicle (SULEV) California medium-duty vehicle standard, the Federal Ultra Low Emission Vehicle (ULEV) standard, and the Federal Inherently Low Emission Vehicle (ILEV) emission standard. The use of natural gas (NG) as a vehicle fuel required unique hardware changes in the areas of fuel storage, fuel metering, and the emission control system.

EPS has now become a compelling technology that nowadays rapidly replacing hydraulic power steering in world market because of its fuel efficiency, sophisticated assist control, additional safety and convenience features. There are various types of EPS such as Column assist type, Pinion assist type and Rack assist type. Small cars with less rack force are equipped with Column or Pinion assist type EPS but for full-sized vehicles with big rack power consumption need Rack assist EPS, what we call R-EPS. Each type of EPS has merits and demerits, but from the perspective of vehicle handling performance, R-EPS has some strong points. And this is why author started this study. Subjective handling evaluation has proven the superiority of R-EPS but objective evaluation was needed. So authors have tried to compare the on center handling characteristics of each EPS on the rig tests and proposed somewhat easy and reliable test method.

The use of Aluminum Metal Matrix Composites (MMC's) is becoming a viable solution to help meet the new regulations of the medium to heavy-duty truck markets. The objective of this paper is to present both analytical and dynamometer data that demonstrate the damage tolerance of a selectively reinforced Aluminum MMC brake drum. In particular, dissimilar coefficients of thermal expansion (CTEs) between the MMC and Aluminum portion of the drum results in favorable compressive stresses in the Aluminum. This state of stress facilitates the slowing of crack growth for flaws whose depth reaches the boundary between MMC and Aluminum. This paper will present an analytical study utilizing finite-element models to predict stress levels in a drum subject to thermal and mechanical loading. Examination of the stress-fields for braking events at room temperature and elevated temperature provides evidence of the aforementioned compressive stresses in the Aluminum portion of the drum.

Dynamic traction testing of a sample of drive tires for class 8 tractor-trailers provides information about the relation among rolling resistance, tire design, and traction performance in snow conditions. The tests were conducted to address concerns that low rolling resistance tires used to save fuel and reduce emissions may have inferior traction on snow. In addition to the dynamic traction testing, based on ASTM F-1805, rolling resistance was tested using ISO 28580, and characteristics of the tread design were measured, including tread depth and void ratio, using ASTM F421 and ASTM F-870. In general, tires designed for increased traction, usually made with open shoulders, had a higher snow traction rating than tires designed for highway applications with closed shoulders. There was no significant correlation between the snow traction rating and the coefficient of rolling resistance.

The increasing use and implementation of computer simulation in the vehicle engineering process has allowed for complex vehicles to be designed and tested in a virtual environment prior to a full-size vehicle being built. This approach is of particular importance in the commercial truck markets of Australia, New Zealand, and South Africa where large truck-trailer combinations, often referred to as “road trains”, are becoming more common. Such trucks can carry more freight per vehicle; however their overall length and mass means additional safety standards must be in place to ensure a safely operating vehicle. To that end the National Transport Commission (NTC) Australia has been developing vehicle specifications called Performance Based Standards, or PBS. Performance Based Standards include specifications for longitudinal performance such as Startability, Gradeability, Acceleration Capability, and Tracking ability on a straight path.

In order to improve ride comfort and reduce interior noise of commercial vehicles, modal sensitivity analysis and optimization design of a commercial vehicle cab was carried out, which increased the first natural frequency of the optimized cab by 23.96%. The result of cab modal test verified the correctness of the finite element model and the effectiveness of the improving method. The structure-acoustic coupling model of the cab was established, and the acoustic response of the coupled sound field was predicted. The sound pressure level of the optimized cab was reduced. In comparison of the optimized cab with the original one, the optimization scheme was confirmed to be effective and reasonable.

In order to obtain the comprehensive evaluation of thermal management system for the retarder, the complete driveline thermal management model is built. The characteristic parameters for the thermal management system are determined and the hydromechanical characteristics for the retarder are fixed by the rig test. On the basis of the same whole vehicle driving cycle, comparing to the traditional mechanical-drive system, the independent-drive system makes the working temperature of the heat source more stable. Meanwhile the parasitic power caused by the radiator fan is decreased markedly on the condition that the heat reject requirement of the heat source is satisfied.

In order to meet the stringent crashworthy regulations and to improve the fuel economy more and more composite materials have been used in automotive industry. The damage and the corresponding failure mechanisms of the composite materials during loading are entirely different from the isotropic materials. The numerical modeling of the above and prediction of the corresponding performance parameters of a composite structure are very important. Normally, the numerical modeling of the composite structures was done with a single layer of shell or solid elements. However, the approach of using single layer of elements cannot capture the effect of delamination which causes the split of the composite structures through thickness. In order to prove this an axial impact study was conducted on cylindrical pultruded glass polyester composite tubes.

The Federal Aviation Administration (FAA) and Coast Guard recently adapted increases in the average passenger weight used to calculate load and conduct safety analysis and tests in multiple modes of transportation. The Federal Transit Authority (FTA) has proposed similar measures. The increased passenger weight requirements were created in response to the Center for Disease Control's (CDC) documented rise in weight among the country's citizens and followed crash or failure incidents in which a cause was overweight equipment. The current certification requirements under CFR 49, Part 567 state that Gross Vehicle Weight Rating (GVWR) of a motor vehicle shall not be less than the sum of the unloaded vehicle weight, rated cargo weight and 150 pounds (68 kg) times the number of designated seating positions. Actual occupant weight distributions versus certified weight per occupant seat causes a potential conflict between a vehicle's in-use weight versus its certified GVWR.

This paper discusses research conducted by the U.S. Army Research Laboratory (ARL) - Vehicle Technology Directorate (VTD) on advanced suspension control. ARL-VTD has conducted research on advanced suspension systems that will reduce the chassis vibration of ground vehicles while maintaining tire contact with the road surface. The purpose of this research is to reduce vibration-induced fatigue to the Warfighter as well as to improve the target aiming precision in-theater. The objective of this paper was to explore the performance effectiveness of various formulations of the Generalized Predictive Control (GPC) algorithm in a simulation environment. Each version of the control algorithm was applied to an identical model subjected to the same ground disturbance input and compared to a baseline passive suspension system. The control algorithms considered include a GPC with Implicit Disturbances, GPC with Explicit Disturbances, and GPC with Preview Control.

The automotive industry is heading towards introduction of newer and newer technology aimed at providing better comforts and value to the end user. The public/ private transport vehicles in urban/rural areas with FE has wide level of acceptance in South East Asian countries. The acceptance of FE buses is mainly because of the ram air cooling of the engine, lesser maintenance, higher fuel efficiency etc whereas rear engine buses with entry plus one step are deprived of these benefits. Hence, we have designed and developed a new Front Engine Semi -Low Floor bus having floor at E+1 step. The primary design challenge was to meet the uniform floor throughout the length of the vehicle. This uniqueness will help in easy ingress and egress of the passengers which helps in reducing the turn around rime of the vehicle. Other challenges includes, meeting the customer requirements in terms of application, load and duty cycle for this new design.

In the truck industry there is a continuous demand to increase the efficiency and to decrease the emissions. To acknowledge both these issues a waste heat recovery system (WHR) is combined with a partially premixed combustion (PPC) engine to deliver an efficient engine system. Over the past decades numerous attempts to increase the thermal efficiency of the diesel engine has been made. One such attempt is the PPC concept that has demonstrated potential for substantially increased thermal efficiency combined with much reduced emission levels. So far most work on increasing engine efficiency has been focused on improving the thermal efficiency of the engine while WHR, which has an excellent potential for another 1-5 % fuel consumption reduction, has not been researched that much yet. In this paper a WHR system using a Rankine cycle has been developed in a modeling environment using IPSEpro.

Semi-active suspension systems for ground vehicles have been the focus of research for several years as they offer improvements in vehicle comfort and handling. This kind of suspension has attracted more interest compared to active suspension systems especially due to lower cost and energy consumption. In this paper the capabilities of a semi-active front axle suspension are investigated for a commercial vehicle. A half-truck model of a 4x2 tractor and semitrailer combination is developed in Matlab/Simulink for this purpose. Also, a 2 DOF roll plane model is considered to capture the roll motion of the vehicle body mass. Employing the above-mentioned models, results from on-off and continuous variable semi-active damping systems are compared to the ones from the passive suspension system according to ride comfort and handling safety characteristics.

The basic scope of heavy-commercial vehicle (HCV) development which was just concentrated on fuel-economy, durability and performance feel is not capable of fulfilling the increasing customer expectations anymore. HCV developers concentrate on additional vehicle attributes such as steering, ride comfort, NVH, braking, ergonomics and exterior-interior design in order to provide the passenger-car like perception to HCV drivers during long distance drives. The objective of this paper is to present the model validation methodology and the optimization study on suspension & steering hard points of a HCV. The results of the optimization study on suspension kinematics and steering performance of the vehicle is verified using both full vehicle simulations and vehicle testing. A full vehicle ADAMS/Car model is used for the validation and optimization study which has beam-element leaf springs on solid axle and air springs on drive axle for front and rear, respectively.

Recent infrastructural developments and emerging automotive market in India has given an impetus to the transportation industry and has led to high end research activities in synchronization with growing customer demands and competition especially in last decade. Since average speeds in India has gone up from 50 kmph in the year 2000 to almost 100 kmph in 2011, even the Light Commercial Vehicles (5 to 9.6T) are gradually experiencing a shift from low speed to high speed goods carrier. These new age vehicles are developed with a driver centric outlook towards safety and comfort. They are better optimized and equipped to the changing needs of the consumer and road conditions. Increase in vehicle speed poses many challenges in terms of occupant safety and control. In view of this, refinement of different vehicle handling parameters with respect to steering system compliance becomes far more critical.

The Articulated Suspension Exploratory Platform (ASEP) is developed in an effort to improve the characteristics and capabilities of the existing recently developed Surface Ground Mobility Platform SGMP. Special attention is placed on the design of the passive suspension mechanism in order for the platform to be suitable for operation in remote and challenging environments. To improve the capacity of the suspension and the overall quality, different designs have been analyzed based on a number of system requirements. The advantages of the final design are its linear motion, obstacle capacities, slope climbing and down-hill stability, as well as compact size and low cost.

In a new technology called “in wheel motor,” in which the motor is installed in the wheel, the electric vehicle can become more compact, which leads to a new type of mobility. Moreover, the front wheel steering is controlled by an electrical unit instead of the traditional mechanical unit of a steering wheel inside the car. In such a “steer-by-wire” method, the motor uses an electric signal. Because the degrees-of-freedom of this steer control are increased and a variety of steer controls based on the electric signal are possible, further improvement of the control stability is needed. In other words, the steer control technique can pose a problem for drivers, and so further research in this area is needed. That is, proportional derivative steering assistance can improve emergency evasion performance and the steering delay upon counter steering. Moreover, rear-wheel active steering can improve vehicle response during emergency evasion maneuvers.