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Sandwich specimens with DP590 steel face sheets and structural epoxy foam cores are investigated under three-point bending conditions. Experimental results indicate that the maximum loads correspond to extensive cracking in the foam cores. Finite element simulations of the bending tests are also performed to understand the failure mechanisms of the epoxy foams. In these simulations, the plastic behavior of the steel face sheets is modeled by the Mises yield criterion with consideration of plastic strain hardening. A pressure sensitive yield criterion is used to model the plastic behavior of the epoxy foam cores. The epoxy foams are idealized to follow an elastic perfectly plastic behavior. The simulation results indicate that the load-displacement responses of some sandwich specimens agree with the experimental results.

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.

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.

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.

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.

The crush strength of aluminum 5052-H38 honeycomb materials under combined compressive and shear loads are investigated here. The experimental results indicate that both the peak and crush strengths under combined compressive and shear loads are lower than those under pure compressive loads. A yield function is suggested for honeycomb materials under the combined loads based on a phenomenological plasticity theory. The microscopic crush mechanism under the combined loads is also investigated. A microscopic crush model based on the experimental observations is developed. The crush model includes the assumptions of the asymmetric location of horizontal plastic hinge line and the ruptures of aluminum cell walls so that the kinematic requirement can be satisfied. In the calculation of the crush strength, two correction factors due to non-associated plastic flow and different rupture modes are considered.

Vehicle motions can adversely affect the ability of a driver or occupant to quickly and accurately push control buttons located in many advanced vehicle control, navigation and communications systems. A pilot study was conducted using the U.S. Army Tank Automotive and Armaments Command (TACOM) Ride Motion Simulator (RMS) to assess the effects of vertical ride motion on the kinematics of reaching. The RMS was programmed to produce 0.5 g and 0.8 g peak-to-peak sinusoidal inputs at the seat-sitter interface over a range of frequencies. Two participants performed seated reaching tasks to locations typical of in-vehicle controls under static conditions and with single-frequency inputs between 0 and 10 Hz. The participants also held terminal reach postures during 0.5 to 32 Hz sine sweeps. Reach kinematics were recorded using a 10-camera VICON motion capture system. The effects of vertical ride motion on movement time, accuracy, and subjective responses were assessed.

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.