Search Results

In this paper the integrated control of front and rear active differentials with active front steering is investigated in order to improve dynamics, stability and to reduce the drawbacks of mechanical self-locking differentials. The proposed integrated centralized control feeds back both the yaw rate and the wheel speed measurements to the control inputs which are the front wheel steering angle and the torque transferred by the electronic differentials between the left and the right wheels of both vehicle's axles. The control of the electronic differentials is not only aimed at keeping the wheel speed differences at desired values but it is also integrated with the active steering control (a PI action from the yaw rate error) to produce a yaw moment (also depending on the yaw rate error) which improves handling and stability.

This paper presents a longitudinal control algorithm for an adaptive cruise control (ACC) with collision avoidance (CA) in multiple vehicle traffic situations. The proposed algorithm consists of a multi-target tracking filter, a primary target selection algorithm and an integrated ACC/CA system. The multi-target tracking filter is used to smooth the sensor signal, and makes it possible to apply to a control system. The primary target selection algorithm decides an in-lane target and provides the information to an integrated ACC/CA system in order to drive a subject vehicle smoothly and improve safety in complex traffic situations. Finally, the integrated ACC/CA system computes the desired acceleration. The performance and safety benefits of the multi-vehicle ACC/CA system is investigated via simulations using real data on driving. Simulation results show that the response of multi-vehicle ACC/CA system is more smooth and safer at a change of traffic situations.

Electronic Stability Control (ESC) has the potential of improving yaw stability and reducing the occurrence of a crash when a vehicle experiences a rear tire tread separation. Two instrumented 4-door, RWD SUV’s equipped with ESC were tested to evaluate the effectiveness of their ESC systems on maintaining yaw stability under these circumstances. The test vehicles were evaluated with the tread and outer steel belt removed from the right rear tire. Tests were run with the ESC engaged and then repeated with the ESC disengaged. All runs were completed with the tires inflated to the manufacturer’s recommended pressure. An analysis of the data collected shows that there are significant differences in the steering input required to generate a loss of control response with and without ESC enabled. Results of Sine with Dwell testing demonstrate a significant reduction in vehicle spinout response with the ESC engaged.

An electric vehicle model has been developed with four direct-drive in-wheel motors. A high-level vehicle stability controller is proposed, which uses the principles of fuzzy logic to determine the corrective yaw moment required to minimize the vehicle sideslip and yaw rate errors. A genetic algorithm has been used to optimize the parameters of the fuzzy controller. The performance of the controller is evaluated as the vehicle is driven through a double-lane-change maneuver. Preliminary results indicate that the proposed control system has the ability to improve the performance of the vehicle considerably.

The paper describes a closed-loop vehicle simulation environment developed to support a virtual vehicle design and testing methodology, proposed for the University of Windsor Formula SAE team. Virtual prototyping and testing were achieved through co-simulation of Matlab/Simulink® and Carsim®. The development of the required hybrid-control driver and vehicle models are described. The proposed models were validated with in vehicle test data. The proposed methods have shown to be effective and robust in predicting driver response, while controlling the vehicle within the developed simulation environment.

One popular complement to track testing that successful race teams use to better understand their vehicle’s behavior is dynamic shaker rig testing, such as 7-post and 8-post testing. Compared to track testing, rig testing is more repeatable, costs less, and can be conducted around the clock. While rig testing certainly is an attractive option, an extensive number of tests may be required to find the best setup. To make better use of rig test time, more efficient testing methods are needed. One method to expedite rig testing is to use rig test data to perform system identification and generate a model of the experiment, which may then be applied to identify potential gains for further rig study. This study develops a system identification method for use in rig testing, using data generated from a known physical model. The results show that this method can be used to accurately predict sensor response during an 8-post test for different shock selections.

Nitrocarburizing is an economical surface hardening process and is proposed as an alternative heat treatment method to carbonitriding. The focus of this study is to compare the size and shape distortion and residual stresses resulting from the ferritic nitrocarburizing and gas carbonitriding processes for SAE 1010 plain carbon steel. Gas, ion and vacuum nitrocarburizing processes utilizing different heat treatment temperatures and times were performed to compare the different ferritic nitrocarburizing processes. Navy C-Ring specimens and prototype stamped parts were used to evaluate size and shape distortion. X-ray diffraction techniques were used to determine the residual stresses in the specimens. Overall, the test results indicate that the nitrocarburizing process gives rise to smaller dimensional changes than carbonitriding, and that the size and shape distortion can be considerably reduced by applying appropriate ferritic nitrocarburizing procedures.

Demands on loaded, rotating components, e.g., bearings, shafts & gears continue to escalate. Modern manufacturing strategies require improvements in traditional measurements and process control tools. Traditionally residual stress examination in bearings was accomplished with depth profiles obtained using X-Ray diffraction (XRD) and electrochemical layer removal. More recently Barkhausen Noise Analysis (BNA) has proven itself in the evaluation of microstructure as well as surface residual stress in ferromagnetic materials. Traditional BN analysis parameters have been used for fixed measurement depths, usually near the surface. This study is an examination on a set of as-hardened and ground bearing rings manufactured with variations in processing. The Barkhausen signal was analyzed to yield information about a range of depths. XRD & BNA depth profiles were gathered and they correlate well. This allows a calibration of the BN signal to the residual stress.

Studies used 1981–2006 FARS and state crash data to examine the relative importance of vehicular, driver, and environmental factors in influencing odds of driver fatality in two-vehicle (car-to-car, light truck-to-car, and light truck-to-light truck) frontal crashes for 1981–2003 model-year vehicles. It was found that all vehicle factors, including vehicle frontal stiffness, have a second order effect compared to vehicle weight. Most of the driver factors included were found to be highly significant. Assumptions and methodology used by other vehicle size/weight safety studies were also evaluated. Results show trends similar to those of other key studies, with one notable exception.

This paper highlights a distinctive, highly-innovative, and project-based approach to supplying cutting-edge, market-driven and industry-focused education courses, at post-graduate level, in key motorsports engineering, business, and management subjects, using a highly-flexible, supported distance learning format. Such courses aim to deliver high-quality, usable knowledge to engineers, managers, and even drivers, with minimum disruption to their normal work patterns.

Clemson University has recently partnered with the State of South Carolina, BMW, Michelin, Timken, and other partner companies to create new MS and PhD programs in Automotive Engineering. These academic programs are housed in a new 90,000 square foot facility located at the newly created Clemson University International Center for Automotive Research (CU-ICAR) in Greenville, SC. This paper describes a unique course, Automotive Development Processes, developed as a part of the Automotive Engineering curriculum by the authors, Dr. Julian Weber, Manager in BMW Electric/Electronics and Driver Environment development in Munich, Germany, and Dr. John Ziegert, a member of the Automotive Engineering Faculty at Clemson University. Due to geographic and time constraints for Dr. Weber, the course is offered as a 2 week intensive course during the university’s Maymester term.

In early design phases vehicle safety testing has revealed the occurrence of both spot weld failure and sheet metal tearing that contributed to below specification performance. This would require redesign and additional testing to meet the specification. Because of cost and weight requirements in vehicle development, it is desirable to create efficient body designs for vehicle safety performance. To develop more efficient structures, it is useful to be able to predict both connection and material failure in a variety of loading conditions using finite element (FE) models. Two new FE methodologies were developed separately to aid in predicting these phenomena. Since it is a widely used explicit FE code, LS-DYNA™ was chosen as the program with which to implement the new material and spot weld models. One methodology uses a force based failure criteria to model failure in, and next to, spot welds.

Emergence of fatty acid methyl esters (biodiesel) as a diesel fuel blend component, as well as fuel additization for management of mandated fuel sulfur reductions, have resulted in dramatic increases in fuel surfactant levels. This step change in fuel surfactancy has given rise to consistent failures of conventional separation and coalescence media used for separation of water from diesel fuel. Reported here are results of coalescing media development efforts that focused on treating fuel-water separation as an adsorption based or liquid-solid separation problem. Stationary phase surface area invariably promotes separation in adsorption based regimes. Media were developed with 60 and 160 fold increases in surface area relative commercial separation media currently used for this application. Media were tested in 7 (B7), 20 (B20), and 40 (B40) percent biodiesel in ultra low sulfur diesel blends.

With the automotive industry using high-pressure common rail fuel systems to meet current and future emissions requirements, water removal is even more critical to extend the life of these fuel systems. To meet this challenge, the automotive industry is attempting to improve the current water removal test methods. International Organization of Standardization (ISO) and Technical Specification (TS) 16332 [1] and Society of Automotive Engineers (SAE) J1488 [2] are the two major standardized test methods used by the automotive industry at this time. ISO/TS 16332 is replacing ISO 4020 [3] and SAE J1488 is still the U.S. National test method. ISO/TS 16322 is still being developed at the time of the writing. The SAE Filter Test Methods Committee (FTMC) is incorporating improved methodologies to SAE J1488 to improve our National test method and meet the automotive industry's needs. This paper will discuss only the SAE FTMC action items and results.

The seatbelt system, originally designed for protecting occupants in frontal crashes, has been reported to be inadequate for preventing occupant head-to-roof contact during rollover crashes. To improve the effectiveness of seatbelt systems in rollovers, in this study, we reviewed previous literature and proposed vertical head excursion corridors during static inversion and dynamic rolling tests for human and Hybrid III dummy. Finite element models of a human and a dummy were integrated with restraint system models and validated against the proposed test corridors. Simulations were then conducted to investigate the effects of varying design factors for a three-point seatbelt on vertical head excursions of the occupant during rollovers. It was found that there were two contributing parts of vertical head excursions during dynamic rolling conditions.

A hardening depth evaluation technique using eddy current has been developed, which can be applied to a mass production line for destructive (cutting) inspections. Using this technique, changes in the hardness of the induction-hardened structure can be detected based on the changes in magnetic permeability. This technique reduces the thermal effect and improves measurement accuracy through a multi-frequency exciting method and a difference method algorithm.

Fuel additives are being used more frequently to meet “premium diesel fuel” requirements. Although these additives improve performance, they also affect the water separation characteristics. This program was designed to determine the effects of various additives on fuel/water separation in low- and ultra-low sulfur diesel fuel. The additives studied include detergents and lubricity additives. A soy-based biofuel is also considered. The fuel/water separation tests conducted with coalescer filter technology generally produced higher efficiencies while the addition of a detergent additive package at 175-ppm generally produced lower water separation efficiencies.

Moving ground systems with rotating wheels have been used in wind tunnel tests during the last decades. Several studies on the effects of rotating wheels and the importance of wheel aerodynamics have been published. It is well known that both the local flow field and the global aerodynamic forces are affected by rotation of the wheels. Different studies indicate that the most significant effect from rotating the wheels is interference effects between the rear wheels and the underbody and vehicle base [1], [2]. A detailed flow field investigation around the wheels in close proximity to the vehicle has been performed on a passenger car in the Volvo Aerodynamic Wind Tunnel. Two omnidirectional 12-hole pressure probes were traversed in a number of planes close to the wheels. Effects of changing different parameters such as ground simulation and rim geometry were investigated. The local flow field has been scrutinised and related to the global aerodynamic properties of the vehicle.

The Advanced Crash Avoidance Technologies (ACAT) program initiated by the National Highway Safety Administration had two major objectives. These were to develop a standardized Safety Impact Methodology (SIM) tool to evaluate the effectiveness of advanced technologies in avoiding and mitigating specific types of vehicle crashes; and to develop and demonstrate objective tests that are used in the SIM to verify the safety impact of a real system. Honda and Dynamic Research Inc. (DRI) have been developing and applying such SIMs for several years and have a Cooperative Agreement with NHTSA to further develop a SIM that provides an estimate of full systems safety benefits at a national level.

Mg96Zn2Y2 cast alloy is composed of an α-Mg phase, Mg12ZnY phase and Mg3Zn3Y2 phase. The coarse dendritic Mg grains have transformed into small cellular Mg grains with the addition of an increasing amount of Zr. Furthermore, increasing the cooling rate led to the precipitation of the fine Mg3Zn3Y2 phase and the Mg12ZnY phase forming a net-like structure. We found that this alloy has mechanical properties equivalent to those of commercial aluminum alloys with good tensile and fatigue properties at temperatures above 473 K.