Search Results

As part of the National Advanced Driving Simulator (NADS) program, the Vehicle Research and Test Center (VRTC) in East Liberty, Ohio is evaluating the NADS vehicle dynamics software. As part of VRTC's effort, an extensive vehicle testing program to provide data for the simulation evaluation was performed. This paper describes VRTC's testing of a 1994 Ford Taurus GL passenger car. Each of the test maneuvers run by the Taurus are described, along with instrumentation setup, control actuation, test conditions, and driver procedures. The test data reduction and processing are detailed. Sample results of the testing and an analysis of test repeatability and measurement noise are also presented.

A sled-to-sled subsystem side impact test methodology has been developed by using two sleds at the WSU Bioengineering Center in order to simulate a car-to-car side impact, particularly in regards to the door velocity profile. Initially this study concentrated on tailoring door pulse to match the inner door velocity profile from FMVSS 214 full-scale dynamic side impact tests. This test device simulates a pulse quite similar to a typical door velocity of a full size car in a dynamic side impact test. Using the newly developed side impact test device three runs with a SID dummy were performed to study the effects of door padding and spacing in a real side impact situation. This paper describes the test methodology to simulate door intrusion velocity profiles in side impact and discusses SID dummy test results for different padding conditions.

This paper describes the development of an automated Door Test Facility for implementing the Door Component Test Methodology for side impact analysis. The automated targeting and loading of the door inner/trim panels with Side Impact Dummy (SID) ribcage, pelvis, and leg rams will greatly improve its test-to-test repeatability and expedite door/trim/armrest development/evaluation for verification with the dynamic side impact test of FMVSS 214 (Occupant Side Impact Protection). This test facility, which is capable of evaluating up to four (4) doors per day, provides a quick evaluation of door systems. The results generated from this test methodology provide accurate input data necessary for a MADYMO Side Impact Simulation Model. The test procedure and simulation results will be discussed.

Automotive engine air intake filters are constantly being challenged to deliver higher filtration performances. The need to protect the engine from abrasive contaminants is ever increasing to achieve longer engine life and improved engine performance. This paper discusses some of the key issues affecting engine filter performance. Currently, the SAE J726 procedure is used to test and evaluate engine air induction filters (AIF). The advantages and limitations of this procedure are discussed. Based on this procedure current engine air filtration technologies are also compared. Engine protection requirements are also discussed relating to contaminant size and concentrations. To design robust engine air induction filters, the particle size and concentration ingested by the engine should be controlled. In addition to the overall mass (gravimetric) efficiency of the filters, the fractional size efficiency of these filters should also be measured.

The objective of this work was to estimate the effects of different filter test housings on measurements of automotive air filter efficiency. This objective was motivated by the questions that arise from designing filters on the basis of uniform face velocities and testing filters in housings providing nonuniform velocities. Velocity distributions upstream of a filter were measured with a laser Doppler anemometer and then used with filtration models to estimate filter initial efficiency. A single filter design was tested in a standard and modified SAE J726 Universal Panel Filter Test Housing and in a housing with a shallow angle diffuser followed by a rectangular duct matched to the filter cross section. The velocity measurements showed that the SAE J726 housing presents a very non-uniform flow to the filter. Housing modifications had small effects. The diffuser-duct housing profiles approach fully-developed duct flow profiles.

A Paper-Tire is a virtual product defined as a set of force and moment equations that are entirely determined by well defined and widely recognized tire characteristics (such as cornering stiffness, peak location, and slide/peak ratio). The vehicle dynamicist may use the Paper-Tire concept to study the effects of tires with various hypothetical characteristics on vehicle behavior. If the dynamicist discovers a set of characteristics yielding a desired vehicle response, he could then ask tire manufacturers to attempt to develop a tire specification with the preferred characteristics. (There is, of course, no guarantee that tire manufacturers can develop a practical tire with the preferred characteristics.) The paper explains the general principles of the Paper-Tire concept with the help of the BNPS model (derived from the ‘Magic Formula’). A limited set of examples for tire cornering and braking performance are provided at a single load; further possible developments are indicated.

The removal of toxic, corrosive, irritant, and odorous gases is a key strategy in improving air quality in any closed space. The technologies of granulated activated carbon or chemically impregnated dry media are commonly employed to address this issue. Both of these methods have their limitations in manufacturability, volume of space, and/or pressure drop associated with use in a given application. A new air quality technology has been developed which integrates liquid based chemisorption gas treatment with a shaped fiber media carrier. The patented wicking fiber shape holds more than its own weight in active reagents within intra-fiber channels. While the liquid volume is captured and retained through capillary action, a large surface area of the chemisorptive liquid is presented to the air flow for reaction and neutralization of the target contaminant gases. The wicking fibers may be implemented as fiber bundles, woven materials, or as non-wovens.

The Variable Dynamic Testbed Vehicle (VDTV) is presently being developed by the National Highway Traffic Safety Administration (NHTSA). It is being designed to have a “steer-by-wire” front steering system and an independent rear steering system. These steering systems enable the VDTV to emulate the directional control characteristics of a broad range of passenger vehicles. In this study, a “model-following” control method is used to modify both the steady-state and transient lateral response characteristics of a small-size VDTV to match those of compact-size and mid-size vehicles. For two classes of steering inputs considered in this study (“pseudo-step” and “sinusoidal”), the model-following control design method allowed the VDTV to accurately and robustly track the lateral responses of the target vehicles over a range of forward speed.

The Variable Dynamic Testbed Vehicle (VDTV) concept has been proposed as a tool to evaluate collision avoidance systems and to perform driving-related human factors research. The goal of this study is to analytically investigate to what extent a VDTV with adjustable front and rear anti-roll bar stiffnesses, programmable damping rates, and four-wheel-steering can emulate the lateral dynamics of a broad range of passenger vehicles. Using a selected compact-sized automobile as a baseline, our study indicated this baseline vehicle can be controlled to emulate the lateral response characteristics (including the vehicle's understeer coefficient and the 90% lateral acceleration rise time in a J-turn maneuver) of a fleet of production vehicles, from low to high lateral acceleration conditions.

This paper describes a tire model designed for the full range of operating conditions under both on- and off-road surface conditions. The operating conditions include longitudinal and lateral slip, camber angle and normal load. The model produces tire forces throughout the adhesion range up through peak coefficient of friction, and throughout the saturation region to limit slide coefficient of friction. Beyond the peak coefficient of friction region, the off-road portion of the model simulates plowing of deformable surfaces at large side slip angles which can result in side forces significantly above the normal load (e.g., equivalent coefficients of friction greatly exceeding unity). The model allows changing the saturation function depending the surface currently encountered by a given tire in the vehicle dynamics model.

The main features of suggested model are as follows. Elastic crankshaft rotates in main bearings, bearing supports elastically deform in the linear and the angular directions under action of forces resulted from journals and bearings interaction. The linear and the angular elasticity limits of supports and crankshaft of a particular engine is a subject of FEM study. The model of dynamically loaded bearings considers the misalignment and the angular displacements of journals and mixed lubrication conditions. A new method to obtain hydrodynamic forces as well as moments is described. In addition to the existing bearing performance evaluation criteria, the deviation criteria has been suggested. The model and its modifications have been on-going basis for study and the improvement of several types of diesel locomotive engines. Some of the results of these studies are presented.

Automotive systems often employ a variety of intercoupled embedded controllers. To ensure that the controller actions are coordinated and that unwanted interaction does not occur, system testing is necessary over the entire operating range of the automotive systems. A cost effective, safe, and convenient means to perform much of the testing of embedded controller code is to use real-time simulation for all or major parts of the automotive system. However, the integration of various automotive system models and controllers into a single simulation model for hard real-time is a difficult task which is complicated by the usual approach of synchronizing the various computational tasks and I/O activites. This paper describes a new methodology involving asynchronous operation of processors and processes.

Transient operation in port-injected engines often results in long lasting air-fuel ratio excursions. These excursions lead to high levels of pollutant emissions even in three-way catalyst equipped vehicles. The reduction of these excursions can be achieved by controlling fuel injection, but the exact amount of fuel to be injected is dependant on air flow and deposited fuel dynamics. This paper describes a complete model of the intake port, taking into account physical evolutions of three phases in a bidimensional geometry. Back-flow of hot burned gases, droplet trajectories, droplet evaporation, deposited fuel film flow, deposited fuel film evaporation, and air flow are taken into account. The model is used to predict air-fuel ratio excursions during engine transients. Results are compared to measurements made on a real four-cylinder engine with an oxygen sensor on the exhaust port of one cylinder, for several operating conditions.

Presented in this paper is the nonlinear modeling and control of the idle speed of a Ford 4.6L-2 valve V-8 fuel injected engine. The nonlinear model of the engine is based on a Hammerstein type model which is identified through input-output data without a priori knowledge of the engine dynamics. The nonlinear model is used in a frequency domain controller design methodology to achieve the performance goal of maintaining the engine idle speed within a prespecified asymmetric output tolerance despite external torque disturbances. An experimental verification of the nonlinear controller is included.

Based on fundamental study about the toughness of hot rolled microalloyed steels, a new steel composed of 0.4 % carbon, 1.10 % manganese, 0.5 % chromium and 0.15 % vanadium was developed. The steel shows high toughness and high proof stress after well-controlled hot rolling. The newly designed steering racks for passenger cars using the steel bar have properties equivalent to the racks of conventional quenched and tempered carbon steels.

An experimental study of two warm and hot forged 0.30% carbon ferrite/pearlite microalloyed steels demonstrates that the optimal combination of strength and toughness is achieved in a warm forged, fan cooled condition. The properties of the warm forged microalloyed steel approached the combination of strength and toughness achieved in a heat treated 1037 steel, tested at an equivalent hardness level of 20 to 28 HRC. These warm forged microalloyed steels were successfully substituted for heat treated 1037/1040 steels in two automotive transmission hub applications. The benefits of implementing the warm forged microalloyed steel hubs include the elimination of the heat treatment, and the associated costs and problems.

A confusing number of equations have been developed and published for calculating the air/fuel ratio of an operating engine from the composition of its exhaust gasses. These methods make varying use of the information available from the gas concentration measurements, but they all are based on the same chemistry of combustion. The method described here is a single algorithm that duplicates the results of all the well known published equations and can adapt to different measurement circumstances, such as when an oxygen measurement is not available or if the gas sampling point is moved to after the catalyst. Data are presented to demonstrate the equivalence of the algorithm and equation evaluations.

There are strong demands for reduced production costs of ordinary bolts, of which a large number are used throughout automobiles. In addition, there are continued demands for higher performance and lower weight in automobiles. For this reason, there is an increasing trend to develop steel for high strength bolts or to adopt the plastic region tightening method. At present, the principal materials used in high strength bolts of class 10.9 are medium carbon alloy steel. When a low carbon boron steel bolt is used as a class 10.9 bolt under high stress, delayed fracture may occur, so that these cannot always be used for the body and chassis applications. The authors have developed a new low carbon boron steel with increased delayed fracture strength on the same order as that of JIS-SCM435 (equivalent to SAE4135) medium carbon alloy steel. Attention was focused principally on decreasing the amounts of phosphorus and sulfur in the steel.

Vibration behavior of a crankshaft in operation is complicated and difficult to simulate because of oil effects on journals, coupled vibration of crankshaft system parts, combustion and inertia acting on the crankshaft. Particularly, the stiffness and damping of oil film vary with crank angles and thus the numerical analysis must deal with nonlinear vibration. This oil film effects also diversify the vibration modes of the crankshat; the vibration modes in an actual operation differs from that in statically experiment modal analysis. This paper describes a new method developed by the author to analyses, predict, and reduce noise and vibration using several techniques including numerical simulation, finite element method, Sommerfeld concept on oil film effects, and modal frequency response.

Time-domain numerical modelling of performance for complete engine systems is now routine in most automotive design offices. To achieve this with a minimal computer run-time overhead, drastic simplification of the exhaust silencer box models is required. Complete exhaust systems are often modelled as simple capacitances bounded by orifices. This is justified on the grounds that the influence of exhaust system geometric detail on the engine torque-speed characteristic is less significant than that of the backpressure of the ‘lumped’ system. In contrast to engine performance, acoustic modelling of silencer boxes is usually carried out in the frequency-domain, since this offers a computationally cost-effective means of including very complex internal geometries with minimal computer time overhead. One limitation of these models is the difficulty of characterising the engine as an acoustic source, though empirical methods are often employed.