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Technical Paper

Evaluation of DIC Based Forming Limit Curve Methods at Various Temperatures of Aluminum Alloys for Automotive Applications

Aluminum alloys are increasingly utilized in automotive body panels and crash components to reduce weight. Accurately assessing formability of the sheet metal can reduce design iteration and tooling tryouts to obtain the desired geometry in aluminum stampings. The current ISO forming limit curve (FLC) procedure is a position dependent technique which produces the FLC based on extrapolation at the crack location. As aluminum sheet metal use increases in manufacturing, accurate determination of the forming limits of this material will be necessary prior to production. New time dependent methods using digital imaging correlation (DIC) account for variations in material behavior by continuously collecting strain data through the material necking point. This allows more accurate FLC determination that is necessary for efficient design in the automotive stamping industry.
Journal Article

Development of a Non-Linear Clutch Damper Experiment Exhibiting Transient Dynamics

Many powertrain structural sub-systems are often tested under steady state conditions on a dynamometer or in a full vehicle. This process (while necessary) is costly and time intensive, especially when evaluating the effect of component properties on transient phenomena, such as driveline clunk. This paper proposes a laboratory experiment that provides the following: 1) a bench experiment that demonstrates transient behavior of a non-linear clutch damper under non-rotating conditions, 2) a process to efficiently evaluate multiple non-linear clutch dampers, and 3) generates benchmark time domain data for validation of non-linear driveline simulation codes. The design of this experiment is based on a previous experimental work on clunk. A commercially available non-linear clutch damper is selected and the experiment is sized accordingly. The stiffness and hysteresis properties of the clutch damper are assumed from the measured quasi-static torque curve provided by the manufacturer.
Journal Article

Advanced Control Strategies for a Roll Simulator - A Feedback Linearization Technique Explored

This paper presents a feedback linearization control technique as applied to a Roll Simulator. The purpose of the Roll Simulator is to reproduce in-field rollovers of ROVs and study occupant kinematics in a laboratory setting. For a system with known parameters, non-linear dynamics and trajectories, the feedback linearization algorithm cancels out the non-linearities such that the closed-loop dynamics behave in a linear fashion. The control inputs are computed values that are needed to attain certain desired motions. The computed values are a form of inverse dynamics or feed-forward calculation. With increasing system eigenvalue, the controller exhibits greater response time. This, however, puts a greater demand on the translational actuator. The controller also demonstrates that it is able to compensate for and reject a disturbance in force level.
Technical Paper

Tractor-Semitrailer Stability Following a Steer Axle Tire Blowout at Speed and Comparison to Computer Simulation Models

This paper documents the vehicle response of a tractor-semitrailer following a sudden air loss (Blowout) in a steer axle tire while traveling at highway speeds. The study seeks to compare full-scale test data to predicted response from detailed heavy truck computer vehicle dynamics simulation models. Full-scale testing of a tractor-semitrailer experiencing a sudden failure of a steer axle tire was conducted. Vehicle handling parameters were recorded by on-board computers leading up to and immediately following the sudden air loss. Inertial parameters (roll, yaw, pitch, and accelerations) were measured and recorded for the tractor and semitrailer, along with lateral and longitudinal speeds. Steering wheel angle was also recorded. These data are presented and also compared to the results of computer simulation models. The first simulation model, SImulation MOdel Non-linear (SIMON), is a vehicle dynamic simulation model within the Human Vehicle Environment (HVE) software environment.
Technical Paper

Establishing Occupant Response Metrics on a Roll Simulator

This paper presents the results of an in-depth study of the measurement of occupant kinematic response on the S-E-A Roll Simulator. This roll simulator was built to provide an accurate and repeatable test procedure for the evaluation of occupant protection and restraint systems during roll events within a variety of occupant compartments. In the present work this roll simulator was utilized for minimum-energy, or threshold type, rollover events of recreational off-highway vehicles (ROVs). Input profiles for these tests were obtained through a separate study involving autonomous full vehicle tests [1]. During simulated roll events anthropomorphic test device (ATD) responses were measured using on-board high speed video, an optical three-dimensional motion capture system (OCMS) and an array of string potentiometers.
Technical Paper

Validation of a Roll Simulator for Recreational Off-Highway Vehicles

A two-degree-of-freedom Roll Simulator has been developed to study the occupant kinematics of Recreational Off-Highway Vehicles (ROVs). To validate the roll simulator, test data was collected on a population of ROVs on the market today. J-turn maneuvers were performed to find the minimum energy limits required to tip up the vehicles. Two sets of tests were performed: for the first set, 10 vehicles were tested, where the motion was limited by safety outriggers to 10-15 degrees of roll; and for the second set, three of these vehicles were re-tested with outriggers removed and the vehicle motion allowed to reach 90 degrees of roll. These quarter-turn rollover tests were performed autonomously using an Automatic Steering Controller (ASC) and a Brake and Throttle Robot (BTR). Lateral and longitudinal accelerations as well as roll rate and roll angle were recorded for all tests.
Journal Article

An Iterative Markov Chain Approach for Generating Vehicle Driving Cycles

For simulation and analysis of vehicles there is a need to have a means of generating drive cycles which have properties similar to real world driving. A method is presented which uses measured vehicle speed from a number of vehicles to generate a Markov chain model. This Markov chain model is capable of generating drive cycles which match the statistics of the original data set. This Markov model is then used in an iterative fashion to generate drive cycles which match constraints imposed by the user. These constraints could include factors such number of stops, total distance, average speed, or maximum speed. In this paper, systematic analysis was done for a PHEV fleet which consists of 9 PHEVs that were instrumented using data loggers for a period of approximately two years. Statistical analysis using principal component analysis and a clustering approach was carried out for the real world velocity profiles.
Technical Paper

Addressing Drivability in an Extended Range Electric Vehicle Running an Equivalent Consumption Minimization Strategy (ECMS)

The EcoCAR Challenge team at The Ohio State University has designed an extended-range electric vehicle capable of 50 miles all-electric range via a 22 kWh lithium-ion battery pack, with range extension and limited parallel operation supplied by a 1.8 L dedicated E85 engine. This vehicle is designed to drastically reduce fuel consumption, while meeting Tier II Bin 5 emissions standards. This vehicle design is implemented in a GM crossover utility vehicle as part of the EcoCAR Challenge. This paper explains the implementation of the vehicle's control strategy in order to maintain high efficiency and improve drivability. The vehicle control strategy employs both distinct operating modes and an Equivalent Consumption Minimization Strategy (ECMS) to find the most efficient operating point. The ECMS strategy does an online search for the most efficient torque split in order to meet the driver's command.

Autonomous Ground Vehicles

In the near future, we will witness vehicles with the ability to provide drivers with several advanced safety and performance assistance features. Autonomous technology in ground vehicles will afford us capabilities like intersection collision warning, lane change warning, backup parking, parallel parking aids, and bus precision parking. Providing you with a practical understanding of this technology area, this innovative resource focuses on basic autonomous control and feedback for stopping and steering ground vehicles. Covering sensors, estimation, and sensor fusion to percept the vehicle motion and surrounding objects, this unique book explains the key aspects that makes autonomous vehicle behavior possible. Moreover, you find detailed examples of fusion and Kalman filtering.
Technical Paper

Micro-Texture Tailored Friction Modeling and Discrete Application in Drawability Improvement

Friction plays an important role in the deep drawing process. Previous research shows friction condition can be tailored by applying micro-textures on tooling surfaces. A friction model is proposed to reveal the mechanism of altering friction condition by configuring micro-texture. A discrete friction concept is proposed to improve drawability of sheet metal and demonstrates numerically on a non-symmetric geometry drawing process.
Technical Paper

Welding Characteristics in Deformation Resistance Welding

Deformation Resistance Welding (DRW) is a process that employs resistance heating to raise the temperature of the materials being welded to the appropriate forging range, followed by shear deformation which increases the contacting surface area of the materials being welded. Because DRW is a new process, it became desirable to establish variable selection strategies which can be integrated into a production procedure. A factorial design of experiment was used to examine the influence of force, number of pulses, and weld cycles (heating/cooling time ratio) on the DRW process. Welded samples were tensile tested to determine their strength. Once tensile testing was complete, the resulting strengths were observed and compared to corresponding percent heat and percent reduction in thickness. Tensile strengths ranged from 107 kN to 22.2 kN. A relationship between the maximum current and the weld variables was established.
Technical Paper

Pedestrian head impact testing and PCDS reconstructions

Pedestrian research and testing at the NHTSA Vehicle Research and Test Center has recently focused on assessment of proposed ISO and EEVC head impact test procedures, and extension of these procedures to additional vehicle frontal surfaces. In addition to test parameter sensitivity evaluation, reconstruction of PCDS (Pedestrian Crash Data Study) cases with laboratory impact tests and computer simulations has been conducted. This paper presents the results of this research.
Technical Paper

Laser Lap Welding of Galvanized Steel with No Gap

Laser welding has long been evaluated as a joining technique for galvanized steels in a lap-joint configuration in the automotive industry. However, a problem associated with the low boiling point of zinc limits the application of the laser process in a lap-joint configuration. Zinc-coatings at the interface of the two coated sheets vaporize during welding and the volume of the zinc vapor expands rapidly. The venting of the zinc vapor from the weld pool causes expulsion of the molten metal during welding and a portion of zinc vapor remains in the weld as porosity after welding. To improve the weld quality of galvanized steel, many efforts have been attempted worldwide, but limited success has been reported. Edison Welding Institute (EWI) investigated the laser weldability of galvanized steel in a lap-joint configuration with no gap using a dual beam laser welding technique.
Technical Paper

Application of Conductive Heat Resistance Seam Welding for Joining a 7075-T6 Alloy and a 5754 Dissimilar Thickness Combination

Conductive heat resistance seam welding (CHRSEW) is a new process developed at Edison Welding Institute for creating butt joints on aluminum sheet. The process uses conventional resistance seam welding equipment, and takes advantage of steel cover sheets on either side of the intended joint. Resulting joints are fusion in character, and can be manufactured at very high welding speeds (∼ 3 to 4 m/min). In this study, the conductive heat resistance seam welding process was extended to some new applications. These included joining a 7075-T6 alloy, and a dissimilar thickness 1- to 2-mm 5754 configuration. The former is generally considered unweldable by fusion methods, and is of considerable interest for aerospace applications. The latter is representative of a tailor welded blank for automotive applications. Resulting welds were evaluated using metallurgical examinations and mechanical testing.
Technical Paper

Vibration Weldability Study for Painted Plastics

Weldability study has been performed on Polypropylene (PP) and PC/ABS samples to investigate how the paint layer along the weld joint affects the vibration weldability. The plastic used for this study were PP representing semicrystalline thermoplastics and PC/ABS representing amorphous thermoplastics. Both resins were molded to generate sample plaques for the study. Design of Experiment (DOE) studies were initially conducted with unpainted plaques and then repeated with the painted plaques for comparison. Optimal welding parameters were determined through DOE and the maximum weld strength under optimized welding conditions were determined and compared. Following each DOE, a regression analysis, using the weld strength as a response, was performed.
Technical Paper

Recent Developments in Friction Stir Welding

Friction stir welding (FSW) is a new welding process developed at The Welding Institute in Cambridge, U.K. This process uses a non-consumable rotating third body to generate frictional heat and create forging to facilitate continuous solid-state joints. In this paper, the current state of the art of FSW is discussed. A preliminary description of the process is provided, followed by the results of some relatively simple thermal modeling. The modeling results are used to provide a description of temperature distributions in FSW, as well as illustrate the effects of variations in process conditions. Representative microstructures of FSW on an Al 6061 alloy are then presented. Properties of these friction stir welds are then discussed and compared to those of both the base metal and to comparable GTAW welds. Some discussion is then given to the effects of section thickness on FSW. Examples are given of friction stir welds on aluminum alloys ranging from 2 to 30 mm in thickness.
Technical Paper

Improving Fillet Weld Fatigue Performance by Improving Weld Shape

The fatigue performance of fillet-welded transverse attachments was compared for several procedure variants for both FCAW and SAW on ½ in. steel plates. Measurements of weld toe shape on adjacent pieces of weld indicated that smoother weld toes, as evidenced by larger weld toe radius, were correlated to improved fatigue performance for both processes. Fatigue tests conducted on 59 and 109 ksi yield strength plates did not show an effect of plate strength. Weld procedures designed to provide smooth toes, such as reduced parameter FCAW beads at horizontal weld toes and flat position FCAW at higher heat inputs, were shown to provide fatigue performances near post-weld improved fillets.
Technical Paper

NVH Research Facilities at The Ohio State University: Existing Facilities and Envisioned Enhancements

The automotive NVH research infrastructure at Ohio State includes the Center for Automotive Research, the Acoustics and Dynamics Laboratory, and the Gear Dynamics and Gear Noise Research Laboratory. This paper describes the facilities of these laboratories. Two unique existing facilities, namely the transmission error measurement of gears and a laboratory for the experimental measurement of engine breathing systems, will be emphasized. Also covered are the enhancements that are envisioned through a recent grant from the Ohio Board of Regents.
Technical Paper

Plasma-Enhanced Catalysis for Automotive Exhausts

This paper presents a concept for enhancing catalytic removal of pollutant species from an exhaust stream by placing placing the plasma adjacent to the catalyst surface. Model calculations of the behavior of the electron energy distribution function (EEDF), which influences the chemistry and ionization levels near the surface, are performed and analyzed. Preliminary experiments attempting to reduce these theoretical ideas to practice in N2/NO mixtures, are discussed. Although removal of NO is observed, this is due to gas phase effects alone. The present experimental arrangement is not able to produce the requisite conditions outlined by theory to enact plasma-enhanced catalysis.
Technical Paper

The Impact of Injection Timing on In-Cylinder Fuel Distribution in a Natural Gas Powered Engine

One obstacle hindering the use of port fuel injection in natural gas engines is poor idle performance due to incomplete mixing of the cylinder charge prior to ignition. Fuel injection timing has a strong influence on the mixing process. The purpose of this work is to determine the impact of fuel injection timing on in-cylinder fuel distribution. Equivalence ratio maps have been acquired by Planar Laser Induced Fluorescence in an optical engine with a production cylinder head. Experimental results have been used to determine the injection timing which produces the most uniform fuel distribution for the given engine.