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Advances in electronic countermeasures for lane-change crashes, including both camera-based rear vision systems and object-detection systems, have provided more options for meeting driver needs than were previously available with rearview mirrors. To some extent, human factors principles can be used to determine what countermeasures would best meet driver needs. However, it is also important to examine sets of crash data as closely as possible for the information they may provide. We review previous analyses of crash data and attempt to reconcile the implications of these analyses with each other as well as with general human factors principles. We argue that the data seem to indicate that the contribution of blind zones to lane-change crashes is substantial.

Workstation design is one of the most essential components of proactive ergonomics, and digital human models have gained increasing popularity in the analysis and design of current and future workstations (Chaffin 2001). Using digital human technology, it is possible to simulate interactions between humans and current or planned workstations, and conduct quantitative ergonomic analyses based on realistic human postures and motions. Motion capture has served as the primary means by which to acquire and visualize human motions in a digital environment. However, motion capture only provides motions for a specific person performing specific tasks. Albeit useful, at best this allows for the analysis of current or mocked-up workstations only. The ability to subsequently modify these motions is required to efficiently evaluate alternative design possibilities and thus improve design layouts.

A quasi-dimensional, multi-zone, direct injection (DI) diesel combustion model has been developed and implemented in a full cycle simulation of a turbocharged engine. The combustion model accounts for transient fuel spray evolution, fuel-air mixing, ignition, combustion and NO and soot pollutant formation. In the model, the fuel spray is divided into a number of zones, which are treated as open systems. While mass and energy equations are solved for each zone, a simplified momentum conservation equation is used to calculate the amount of air entrained into each zone. Details of the DI spray, combustion model and its implementation into the cycle simulation of Assanis and Heywood [1] are described in this paper. The model is validated with experimental data obtained in a constant volume chamber and engines. First, predictions of spray penetration and spray angle are validated against measurements in a pressurized constant volume chamber.

Interference between physical objects in the workspace and the moving human body may cause serious problems, including errors in manual operation, physical damage and trauma from the collision, and increased biomechanical stresses due to movement reorganization for avoiding the obstacles. Therefore, a computer algorithm to detect possible collisions and simulate human motions to avoid obstacles will be an important tool for computer-aided ergonomics and optimization of system design in the early stage of a design process. In the present study, we present a method of modifying motions for obstacle avoidance when the object intrudes near the center of the planned motion. We take the motion modification approach, as we believe that for a certain class of obstacle avoidance problems, a person would modify a pre-planned motion that would result in a collision to a new one that is collision-free, as opposed to organizing a totally unique motion pattern.

Although biomechanics models can predict the stress on the musculoskeletal system, they cannot predict how the muscle load associated with exertion is perceived. The short-term goal of the present study was to model the perception of effort in lifting and reaching tasks. The long-term goal is to determine the correlation between objective and subjective measures of effort and use this information to predict fatigue or the risk of injury. Lifting and reaching tasks were performed in seated and standing situations. A cylindrical object and a box were moved with one hand and two hands, respectively, from a home location to shelves distributed in the space around the subject. The shoulder and torso effort required to perform these tasks were rated on a ten point visual analog scale.

Numerical models are used for computing the shock response in many areas of engineering applications. Current analysis methods do not account for uncertainties in the model parameters. In addition, when numerical models are calibrated based on test data neither the uncertainty which is present in the test data nor the uncertainty in the model are taken into account. In this paper an approach for model update under uncertainty and error estimation for shock applications is presented. Fast running models are developed for the model update based on principal component analysis and surrogate models. Once the numerical model has been updated the fast running models are employed for performing probabilistic analyses and estimate the error in the numerical solution. The new developments are applied for computing the shock response of large scale structures, updating the numerical model based on test data, and estimating the error in the predictions.

Analytical and experimental investigations of a diesel engine cylinder block are performed. An attempt is made to reduce modeling and analysis costs in the design process of an engine. Traditionally, the engine has been modeled using either 8-node or 20-node solid elements for stress and thermal analyses and modeled using 4-node plate and shell elements for the dynamic analysis. In this paper, a simpler finite element modeling technique using only 8 node solid elements for both dynamic and static analyses is presented. Based on this integrated modeling technique of finite elements, eigenvalues are calculated and compared with the experimental data obtained from modal testing of an actual engine cylinder block.

A combined experimental and analytical approach was followed in this work to study stress distributions and causes of failure in diesel cylinder heads under steady-state and transient operation. Experimental studies were conducted first to measure temperatures, heat fluxes and stresses under a series of steady-state operating conditions. Furthermore, by placing high temperature strain gages within the thermal penetration depth of the cylinder head, the effect of thermal shock loading under rapid transients was studied. A comparison of our steady-state and transient measurements suggests that the steady-state temperature gradients and the level of temperatures are the primary causes of thermal fatigue in cast-iron cylinder heads. Subsequently, a finite element analysis was conducted to predict the detailed steady-state temperature and stress distributions within the cylinder head. A comparison of the predicted steady-state temperatures and stresses compared well with our measurements.

Quantitative LIF measurements of liquid fuel films on the piston of direct-injected gasoline engines are difficult to achieve because generally these films are thin and the signal strength is low. Additionally, interference from scattered laser light or background signal can be substantial. The selection of a suitable fluorescence tracer and excitation wavelength plays an important role in the success of such measurements. We have investigated the possibility of using toluene as a tracer for fuel film measurements and compare it to the use of 3-pentanone. The fuel film dynamics in a motored engine at different engine speeds, temperatures and in-cylinder swirl levels is characterized and discussed.

Dummy response and restraint configuration factors associated with a known child injury environment were investigated using a spinal-cord injury accident case, a full-scale reconstruction, and sled simulations. The work is one of several studies undertaken in association with the International Task Force on Child Restraining Systems to support the development of improved neck injury criteria and restraint systems for young children. A two-vehicle crash involving a restrained child occupant was investigated in detail and reconstructed in full-scale at the Transport Canada Motor Vehicle Test Centre using the CRABI 6-Month dummy. Vehicle damage and crush characteristics closely resembled that of the case vehicles. Dummy instrumentation included head and chest accelerometers and upper and lower neck transducers. The case occupant had been facing forward and had sustained a contusion of the spinal cord at T2 that resulted in paraplegia.

Static deployments of driver-side airbags into the legs of human subjects were used to investigate the effects of inflator capacity, internal airbag tethering, airbag fabric, and the distance from the module on airbag-induced skin abrasion. Abrasion mechanisms were described by measurements of airbag fabric velocity and target surface pressure. Airbag fabric kinematics resulting in three distinct abrasion patterns were identified. For all cases, abrasions were found to be caused primarily by high-velocity fabric impactrather than scraping associated with lateral fabric motion. Use of higher-capacity inflators increased abrasion severity, and untethered airbags produced more severe abrasions than tethered airbags at distances greater than the length of the tether. Abrasion severity decreased as the distance increased from 225 to 450 mm. Use of a finer-weave airbag fabric in place of a coarser-weave fabric did not decrease the severity of abrasion.

A four-valve-pentroof, direct-injection, optical engine fueled with n-heptane has been operated at four different steady-state HCCI operating conditions including 10% and 65% residuals, both at low and high swirl conditions. Both, planar toluene LIF and volume chemiluminescence show large scale inhomogeneity in the ensemble averaged images. The interpretation of the toluene-tracer LIF signals (when premixed with the fresh-air charge) as a marker for reaction homogeneity is discussed. A binarization scheme and a statistical analysis of the LIF images were applied to the per-cycle planar-LIF images revealing inhomogeneities both from cycle-to-cycle and within the regions of individual cycles that track with the average heat release rate. Comparison of these two homogeneity metrics between the four operating conditions reveals weak but discernable differences.

Night vision enhancement systems (NVES), which use infrared (IR) cameras, are designed to supplement the visibility provided by standard headlamps. There are two main NVES systems: active, near infrared (NIR) systems, which require an IR source but give a complete picture of the scene in front of the driver, and passive, far infrared (FIR) systems, which do not need an IR source but only enhance relatively warm objects (such as people and animals). There are three main display alternatives: a head-up display (HUD) superimposed on the direct view of the road, a HUD just above the dashboard but separated from the direct view, and a conventional display somewhere in the dashboard. This paper analyzes what a NVES should do to improve night visibility based on night crash statistics, driver vision and visibility conditions in night driving, driver tasks and behavior, and the options offered by various technological approaches. Potential problems with using NVES are also discussed.

Coordinate measurement gages dominate in the area of dimensional control and variation reduction of automotive body assembly processes. However, coordinate measurement gages do not have the capability to track certain measured features. This incapability introduces inherent measurement error created by part (feature) mislocation in constrained non-measured directions. This inherent measurement error weakens the methods used for process control and variation reduction. In this paper, a principle of measurement uncertainty is developed in order to estimate the measurement error caused by this deficiency. The developed principle describes measurement error, which is independent of any other error related to the mechanical or optical coordinate measurement machines (CMMs, OCMMs). Additionally, an error map determined by the measurement uncertainty principle is created for error compensation.

For applications of planar laser induced fluorescence (PLIF) to measure the fuel or equivalence ratio distributions in internal combustion (IC) engines it is typically assumed that the addition of a fluorescence tracer to a base fuel does not alter the combustion performance. We have investigated the impact on combustion performance through the addition of various amounts of 3-pentanone or toluene to iso-octane fuel. Correlations between equivalence ratio for a range of fuel/tracer mixtures and engine parameters, like peak pressure, location of peak pressure, indicated mean effective pressure (IMEP), and peak burn rate are discussed for data obtained in a spark-ignition direct-injection (SIDI) gasoline engine operated with near homogeneous charge. For typical tracer concentrations the impact on combustion performance is mostly negligible.

The increasing availability of camera-based displays for indirect vision in vehicles is providing new opportunities to supplement drivers' direct views of the roadway and surrounding traffic, and is also raising new issues about how drivers perceive the positions and movements of surrounding vehicles. We recently reported evidence that drivers' perception of the distance to rearward vehicles seen in camera-based displays is affected not only by the visual angles subtended by the images of those vehicles, but also by the sizes of those images relative to the sizes of the displays within which they are seen (an influence that we have referred to as a framing effect). There was also evidence for a similar, but weaker, effect with rearview mirrors.

We have proposed First Order Analysis (FOA) as a method, which the engineering designers themselves can use easily in an initial design stage. In this paper, we focus on the crashworthiness, and present the method to predict the collapse behavior of the frame member. This method is divided into two parts. Those are (1) collapse analysis under loading conditions of combined axial force and bending moment to the cantilever, and (2) collapse analysis of structural member considering the previously obtained moment - rotation angle relationship using the beam element. In comparison with the results according to the detailed Finite Element Analysis (FEA) model, effectiveness and validity of this method are presented.

In this paper, the formability of AA5754 aluminum laser-welded blanks produced by Nd:YAG laser welding is investigated under biaxial straining conditions. The mechanical behavior of the laser-welded blanks is first examined by uniaxial tensile tests conducted with the weld line perpendicular to the tensile axis. Shear failure in the weld metal is observed in the experiments. Finite element simulations under generalized plane strain conditions are then conducted in order to further understand the effects of weld geometry and strength on the shear failure and formability of these welded blanks. The strain histories of the material elements in the weld metal obtained from finite element computations are finally used in a theoretical failure analysis based on the material imperfection approach to predict the failure strains for the laser-welded blanks under biaxial straining conditions.

Experiments to obtain the failure loads of spot welds are first reviewed under combined opening and shear loading conditions. A failure criterion is then presented for spot welds under combined opening and shear loading conditions based on the results from the experiments and a lower bound limit load analysis. In order to account for spot welds under more complex loading conditions, another lower bound limit load solution is presented to characterize the failure loads of spot welds under combinations of three forces and three moments. Based on the limit load solution, 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 sheet thickness, nugget radius and combinations of loads.

The spark process has previously been shown to heavily influence ignition stability, particularly in direct-injected gasoline engines. Despite this influence, few studies have addressed spark behavior in direct-injected engines. This study examines the role of environmental factors on the behavior of the spark. Through measurement of the spark duration, by way of the ignition current trace, several observations are made on the influence of external factors on the behavior of the spark. Changing the level of nitrogen in the cylinder (to simulate EGR), the level of wetting and velocity imparted by the spray, the ignition dwell time and the orientation of the ground strap, observations are made as to which conditions are likely to produce unfavorable (shorter) spark durations. Through collection of a statistically significant number of sample spark lengths under each condition, histograms have been assembled and compared under each case.