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One of the primary reasons that FMVSS 111 currently requires flat rearview mirrors as original equipment on the driver's side of passenger cars is a concern that convex mirrors might reduce safety by causing drivers to overestimate the distances to following vehicles. Several previous studies of the effects of convex rearview mirrors have indicated that they do cause overestimations of distance, but of much lower magnitude than would be expected based on the mirrors' levels of image minification and the resulting visual angles experienced by drivers. Previous studies have investigated mirrors with radiuses of curvature up to 2000 mm. The present empirical study was designed to investigate the effects of mirrors with larger radiuses (up to 8900 mm). Such results are of interest because of the possible use of large radiuses in some aspheric mirror designs, and because of the information they provide about the basic mechanisms by which convex mirrors affect distance perception.

A general failure criterion for spot welds is proposed with consideration of the plastic anisotropy and the separation speed for crash applications. A lower bound limit load analysis is conducted to account for the failure loads of spot welds under combinations of three forces and three moments. Based on the limit load solution and the experimental results, an engineering failure criterion is proposed with correction factors determined by different spot weld tests. The engineering failure criterion can be used to characterize the failure loads of spot welds with consideration of the effects of the plastic anisotropy, separation speed, sheet thickness, nugget radius and combinations of loads. Spot weld failure loads under uniaxial and biaxial opening loads and those under combined shear and twisting loads from experiments are shown to be characterized well by the engineering failure criterion.

Current automotive design practices related to driver visibility are based on static laboratory studies of mostly straight ahead viewing that were conducted by Meldrum and others beginning in 1962. These individual studies have never been replicated either in the lab or in actual driving situations to determine the validity of their procedures. After a thorough review of the literature related to driver eye location and a statistical analysis of previous static eye location data, an experimental design is proposed to determine dynamic eye location distribution characteristics. This design will provide information on: (a) the relationship of static anthropometric measurements to dynamic eye location; (b) the difference between dynamic on-the-road eye location versus static in-the-lab eye location distributions: (c) the effect of different types of vehicle seating package parameters on eye location; and, (d) a validation of previous static eye location studies.

In recent years, automotive occupant restraint system development has gained impetus, stimulated, in part, by new federal standards. But in the resolution of the basic question of whether automobiles should be equipped with restraints, many new problems have arisen, including, ironically, some brought on by regulation. While there is little doubt that restraint systems can provide the single most important contribution to occupant protection, such restraint systems remain useless unless adequately installed and properly worn. Current problems involve not only what concepts provide most promise for future restraint systems, but diverse and often conflicting industry and governmental opinion about what are the best interests of the motoring public. Restraints are still not provided in buses, trucks, and utility vehicles. In addition, the problems of child and infant restraints and restraints for retrofit in older vehicles remain unresolved.

Five different nonplanar mirrors were evaluated as driver-side rearview mirrors in a field test using Ford employees. Two were spherical convex (differing in radius of curvature), and three were aspheric (differing primarily in the proportion of their surfaces over which radius of curvature was variable). Each participant drove for four weeks with one of the nonplanar mirrors. At three times during the test the participants filled out questionnaires concerning their experience with the mirrors. Driver preferences for the experimental mirrors increased moderately between surveys at one week and at four weeks. At four weeks, all five nonplanar mirrors were preferred to the standard flat mirror by at least a small amount. For each of the five mirror designs there was a large range of opinion. Most notably, a small number of people strongly disliked the aspheric design that involved the largest variable-radius area.

A formulation that accounts for manufacturing variability in the analysis of structural/acoustic systems is presented. The methodology incorporates the concept of fast probability integration with finite element (FEA) and boundary element analysis (BEA) for producing the probabilistic acoustic response of a structural/acoustic system. The advanced mean value method is used for integrating the system probability density function. FEA and BEA are combined for producing the acoustic response that constitutes the performance function. The probabilistic acoustic response is calculated in terms of a cumulative distribution function. The new methodology is used to illustrate the difference between the results from a probabilistic analysis that accounts for manufacturing uncertainty, and an equivalent deterministic simulation through applications. The probabilistic computations are validated by comparison to Monte Carlo simulations.

An effective fatigue driving stress is proposed to predict the failure of spot welds under cyclic combined loading conditions. The effective fatigue driving stress is obtained based on the Mises yield criterion in terms of the resultant forces and moments in a plastic collapse analysis of spot welds under complex combined loading conditions as discussed in Lin et al. [1]. The effective fatigue driving stress can be used to correlate the fatigue data of spot welds with consideration of the effects of the sheet thickness, nugget diameter and loading conditions. Experimental results for coach-peel and lap-shear specimens under cyclic loading conditions are used to evaluate the applicability of the effective fatigue driving stress. The experimental results for spot welds in both coach-peel and lap-shear specimens are correlated very well based on the effective fatigue driving stress.

In the I-bumper (inflatable bumper) concept [1], two explosive airbags are released just before the main body-to-body crash in order to absorb the kinetic energy of colliding vehicles. The release also actuates other components in the I-bumper, including a movable bumper and an energy absorption morphing lattice structure. A small explosive charge will be used to deploy the airbag. A conventional airbag model will be used to reduce the crash energy in a controlled manner and reduce the peak impact force. An analytic model of the explosive airbag is developed in this paper for the I-bumper system and for its optimal design, while the complete system design (I-bumper) will be discussed in a separate paper. Analytical formulations for an explosive airbag will be developed and major design variables will be identified. These are used to determine the required amount of explosive and predict airbag behavior, as well to predict their impact on the I-bumper system.

The greatest demand facing the automotive industry has been to provide safer vehicles with high fuel efficiency at minimum cost. Current automotive vehicle structures have one fundamental handicap: a short crumple zone for crash energy absorption. This leaves limited room for further safety improvement, especially for high-speed crashes. Breakthrough technologies are needed. One potential breakthrough is to use active devices instead of conventional passive devices. An innovative inflatable bumper concept [1], called the “I-bumper,” is being developed by the authors for crashworthiness and safety of military and commercial vehicles. The proposed I-bumper has several active structural components, including a morphing mechanism, a movable bumper, two explosive airbags, and a morphing lattice structure with a locking mechanism that provides desired rigidity and energy absorption capability during a vehicular crash.

An automotive absorption air conditioning system would use engine-rejected heat as its energy source. Three possible cycles were studied, based on using water-lithium bromide, ammonia-water, and refrigerant 22-dimethyl ether of tetraethylene glycol as the refrigerant-absorbent pairs. Heat balances were calculated for the cycles and for a comparable vapor compression cycle. Energy input requirements, cooling capacities, coefficients of performance, and pressures and temperatures at various points in the cycle are given. Energy input requirements are compared with test data on the heat rejection from a 390 cu in. displacement production engine.

This analytical study examined the potential benefits of applying two embodiments of adaptive lighting to the U.S. and European low-beam patterns: curve lighting that involves shifting the beam horizontally into the curve, and motorway lighting that involves shifting the beam vertically upward. The curve lighting simulations paired 240-m radius left and right curves with a horizontal shift of 10°, and 80-m radius curves with a horizontal beam shift of 15°. The motorway lighting simulations involved upward aim shifts of 0.25° and 0.5°. For both curve and motorway lighting, changes in both seeing and glare illuminance were considered. Market-weighted model year 2000 U.S. and European beam patterns were used. We conclude that curve lighting, as simulated here, would substantially improve seeing performance on curves for both types of beams. On right curves (but not on left curves) there would be an increase in disability glare for oncoming traffic.

The nature of the potentially hazardous interaction between a passenger-side airbag and a rear-facing child restraint is described, as well as the expectations regarding airbag interaction with other types of child restraint systems. Progress made in developing tools to study the problem and test criteria to evaluate possible solutions are summarized, efforts to inform the public are noted, and promising directions for dealing with the problem are addressed. Primary emphasis is placed on the work of the Society of Automotive Engineers (SAE) Child Restraint and Airbag Interaction (CRABI) Task Force and that of its members.

Closed-form stress intensity factor solutions at the critical locations of spot welds in four types of commonly used specimens are obtained based on elasticity theories and fracture mechanics. The loading conditions for spot welds in the central parts of four types of specimens are first examined. The resultant loads on the weld nugget and the self-balanced resultant loads on the lateral surface of the central parts of the specimens are then decomposed into various types of symmetric and anti-symmetric parts. Closed-form structural stress and stress intensity factor solutions for spot welds under various types of loading conditions are then adopted from a recent work of Lin and Pan to derive new closed-form stress intensity factor solutions at the critical locations of spot welds in the four types of specimens.

When performing vibration analysis of complex vehicle structures, it is often important to be able to evaluate the effects of design changes in one or more substructures (e.g., for design optimization). It may also be convenient to allow different components to be modeled independently by different groups or organizations. For both cases, it is inevitable that some substructures will have non-matching finite element meshes at the interface where they are physically connected. Thus, a key challenge is to be able to handle the dynamic assembly of components with non-matching meshes and the subsequent global vibration analysis in a systematic and efficient manner. To tackle this problem, the enhancement of component mode synthesis methods for handling finite element models partitioned into non-matching substructures is considered in this paper. Some existing methods are reviewed, and new methods are developed.

This paper presents a general control module to control the speed of an electric vehicle (EV). This module consists of a microprocessor and several C-programmable micro-controllers. It uses an identification algorithm to estimate the system parameters on-line. With the estimated parameters, control gains are calculated via pole-placement. In order to compensate for the internal errors, a cross-coupling control algorithm is included. To estimate the true velocity and acceleration from measurements, a discrete-time Kalman filter was utilized. The experimental results validate the general control module for EVs.

The Federal Motor Vehicle Safety Standards currently require driver-side rearview mirrors to be flat. For rearview mirrors of typical size, this requirement normally results in a blind zone on the driver side that is large enough to conceal an average size passenger car. In recent years a number of studies have suggested that nonplanar rearview mirrors may be an effective solution to this problem. This paper reviews the evidence on possible effectiveness of nonplanar mirrors, assesses the strength of that evidence, and makes tentative recommendations. The main conclusion is that the use of nonplanar mirrors would probably result in a net gain in safety, but that the effectiveness of the mirrors is likely to depend on details of how they are implemented. Issues that should be resolved by additional research (some of which is already underway) are: (1) How would U.S. drivers respond to a mixed fleet of vehicles, some of which had flat mirrors and some of which had nonplanar mirrors?

The effects of image size on perceived distance have been of concern for convex rearview mirrors as well as camera-based rear vision systems. We suggest that the importance of image size is limited to cases-such as current rearview mirrors-in which the field of view is small. With larger, richer fields of view it is likely that other distance cues will dominate image size, thereby substantially diminishing the concern that distortions of size will result in distortions of distance perception. We report results from an experiment performed in a driving simulator, with static simulated rearward images, in which subjects were asked to make judgments about the distance to a rearward vehicle. The images showed a field of view substantially wider than provided by any of the individual rearview mirrors in current systems. The field of view was 38 degrees wide and was presented on displays that were either 16.7 or 8.5 degrees wide, thus minifying images by factors of 0.44 or 0.22.

The importance of eye-to-display distance for distance perception in rear vision may depend on the type of display. At least in terms of its influence on the effective magnification of images, eye-to-display distance is almost irrelevant for flat rearview mirrors, but it is important for convex rearview mirrors and for other displays, such as video displays, that create images closer to the driver than the actual objects of interest. In the experiment we report here, we investigate the influence of eye-to-display distance on distance perception with both flat rearview mirrors and camera-based video displays. The results indicate that a simple model of distance perception based on the visual angles of images is not very successful. Visual angles may be important, but it appears that relationships between images of distant objects and the frames of the displays are also important. Further work is needed to fully understand how drivers might judge distance in camera-based displays.

Advances in camera and display technology have increased interest in using camera-based systems for all rear-vision functions. The flexibility of camera-based systems is unprecedented, and raises the possibility of providing drivers with fields of view that are very different from, and potentially much better than, those of conventional rearview mirrors. Current fields of view are based on a combination of driver needs and the practical constraints of mirror systems. In order to make the best use of the greater flexibility offered by cameras, a reassessment of drivers' needs for rear vision is needed. A full reassessment will require consideration of many factors. This paper offers a preliminary analysis of one of those factors: the visual workload involved in using rear-vision systems with single versus multiple displays.

High-intensity discharge (HID) headlamps have several advantages over tungsten-halogen headlamps, including greater light efficiency (lumens per watt) and longer life. However, from the safety point of view, the primary attraction of HID headlamps is that, because they produce more total light, they have the potential to provide more useful illumination to the driver. At the same time, there are concerns with the effects of HID illumination on perception of the colors of important objects and glare to oncoming traffic. This paper reviews research evidence that we have accumulated over the past 14 years concerning the potential benefits and drawbacks associated with the use of HID headlighting. We conclude that the evidence strongly supports the use of well-designed HID headlamps.