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Current state-of-the-art vehicles implement pedestrian protection features that rely on pedestrian detection sensors and algorithms to trigger when impacting a pedestrian. During the development phase, the vehicle must “learn” to discriminate pedestrians from the rest of potential impacting objects. Part of the training data used in this process is often obtained in physical tests utilizing legform impactors whose external biofidelity is still to be evaluated. This study uses THUMS as a reference to assess the external biofidelity of the most commonly used impactors (Flex-PLI, PDI-1 and PDI-2). This biofidelity assessment was performed by finite element simulation measuring the bumper beam forces exerted by each surrogate on a sedan and a SUV. The bumper beam was divided in 50 mm sections to capture the force distribution in both vehicles. This study, unlike most of the pedestrian-related literature, examines different impact locations and velocities.

Power steering systems provide significant design challenges. They are detrimental to fuel economy since most require the continuous operation of a hydraulic pump. This generates heat that must be dissipated by fluid lines and heat exchangers. This paper presents a simple one-dimensional transient model for power steering components. The model accounts for the pump power, heat dissipation from fluid lines, the power steering cooler, and the influence of radiation heat from exhaust system components. The paper also shows how to use a transient thermal model of the entire system to simulate the temperatures during cyclic operation of the system. The implications to design, drive cycle simulation, and selection of components are highlighted.

In 1972, the first SAE paper describing the use of computer simulation as a design tool for automotive air conditioning was written by these authors. Since then, many such simulations have been used and new tools such as CFD have been applied to this problem. This paper reviews the work over that past 35 years and presents several of the improvements in the basic component and system models that have occurred. The areas where “empirical” information is required for model support and the value of CFD cabin and external air flow modeling are also discussed.

A kinematic analysis of the head-neck unit has been conducted in 37 simulated traffic accidents in order to investigate correlations between neck response and injuries. Belted fresh human cadavers in the age range 18 to 74 years have been used as front and rear-seat passengers. The analysed data included 23 frontal collisions, impact velocity 30 km/h, 50 km/h and 60 km/h, barrier impact and 14 90°-car to car lateral collisions with near-side passengers (6 cases) as well as far-side rear-seat passengers with an in-board upper anchoring point for the shoulder belt (8 cases). The head bending angle depended on the type of the collision. At the frontal collision, the mean head bending maxima amounted 79°, the evaluated mean angular velocity maxima and angular acceleration maxima corresponded to 41 rad/s and 2208 rad/s2, the mean maximum velocity in trajectory of the head was 10 m/s, the mean maximum acceleration along the path amounted 23 g.

This analysis is part of a retrospective real accident study of 670 occupants in 428 cars. In most cases the real accidents were reconstructed from police reports by means of photographs, accident drawings and descriptions of the damaged cars. In fatal crashes the cars, and in most cases the sites of the accidents were examined. Among 272 occupants involved in car side collisions, we found 41 belt protected near side front passengers, whose cars were impacted by another car with main impact points at the front passengers' doors and B-pillars. The analysis of the correlation between technical parameters of the real accidents and injuries of the passengers showed a high significant discrimination between MAIS and some regional AIS 0-3 on one hand, and MAIS and some regional AIS 4-6 on the other hand already for each of the technical variables EES, delta v and maximum deformation.

Recently there has been a greater awareness of the increased risk of certain injuries associated with air bag deployment, especially the risks to small occupants, often women. These injuries include serious eye and upper extremity injuries and even fatalities. This study investigates the interaction of a deploying air bag with cadaveric upper extremities in a typical driving posture; testing concentrates on female occupants. The goals of this investigation are to determine the risk of upper extremity injury caused by primary contact with a deploying air bag and to elucidate the mechanisms of these upper extremity injuries. Five air bags were used that are representative of a wide range of air bag ‘aggressivities’ in the current automobile fleet. This air bag ‘aggressivity’ was quantified using the response of a dummy forearm under air bag deployment.

The number of passenger cars equipped with side air bags is steadily increasing. With the aim of investigating the mechanical responses and the injuries of the arm under the influence of a side air bag, tests in probably higher injury risk configurations with dummies and cadavers were performed. The air bag was installed at the outer side of the seat back, with the subject seated in the driver or front passenger seat of a passenger car. During the inflation of the air bag, the left or right forearm of the subject was positioned on the arm rest while the upper arm made contact with the seat back edge. The volume of the thorax air bag was 15 litres and for the thorax-head air bag 28 litres. The dummy was instrumented at the thorax c.g. shoulder, elbow and wrist with triaxial accelerometers. In the cadaver, triaxial accelerations in three orthogonal directions were measured at the upper and the lower humerus, the upper radius and the lower radius and the first thoracic vertebrae.

The poisoning of three way catalysts (TWC) by the phosphorus contained in oil formulations containing zinc dialkyldithiophosphate (ZDDP) is examined. Catalysts were exposed to various types of ZDDP and detergents under conditions that were known to reduce performance through phosphorus poisoning without the blocking of sites by formation of glazing. The presence of phosphorus was detected with energy dispersive x-ray spectroscopy (EDX). In addition to analyzing the surface concentration of the phosphorus on the washcoat, the catalyst was cross cut so phosphorus that diffused into the washcoat could be mapped. The total phosphorus in the catalyst could then be calculated. The amount of total phosphorus detected correlated well with the reduced activity of the catalyst as measured by the temperature of 50% conversion.

This paper evaluates the biofidelity of the Hybrid III 5th percentile female dummy relative to seven small female cadavers tested as out-of-position drivers in static air bag deployment tests. In the out-of-position tests, the chest was positioned against the air bag module in an effort to recreate a worst-case loading environment for the thorax. Two pre-depowered production air bags and a prototype dual-stage air bag were evaluated. Thoracic accelerometers and chestbands were used to compare chest compression, velocity, acceleration, and Viscous Criteria. A statistical comparison of dummy and cadaver results indicate acceptable biofidelity of the Hybrid III dummy with significant differences observed only in the Viscous Criteria.

The Cummins M-11 high soot diesel engine test is a key tool in evaluating lubricants for the new PC-7 (CH-4) performance category. M-11 rocker arms and crossheads from tests with a wide range of lubricant performance were studied by surface analytical techniques. Abrasive wear by primary soot particles is supported by the predominant appearance of parallel grooves on the worn parts with their widths matching closely the primary soot particle sizes. Soot abrasive action appears to be responsible for removing the protective antiwear film and, thus, abrades against metal parts as well. Subsequent to the removal of the antiwear film, carbide particles, graphite nodules, and other wear debris are abraded, either by soot particles or sliding metal-metal contact, from the crosshead and rocker arm metal surfaces. These particles further accelerate abrasive wear. In addition to abrasive wear, fatigue wear was evident on the engine parts.

One Dimensional models for front end air flows through the cooling system package are very useful for evaluating the effects of component and front end geometry changes. To solve such models for the air flow requires a robust iterative process that involves a number of non-linear sub-models. The cooling fan (s) constitute a major part of the difficulty, especially when they employ a viscous or “thermal” fan drive. This drive varies the torque coupling between the input and output shafts based on the radiator outlet air temperature. The coupling is achieved by viscous shear between two grooved disks and is regulated by a bimetal strip valve that varies the amount of fluid between the disks. This paper presents a mathematical model by which the input/output speed ratio may be determined as a function of the air temperature and input speed. Coefficients in the model are estimated from standard supplier performance information.

Simple component models are advantageous when simulating vehicle AC systems so that overall model complexity and computation time can be minimized. These models must be robust enough to avoid instability in the iteration method used for determining the AC system operating or “balance” point. Simplicity and stability are especially important when the AC system model is coupled with a vehicle interior model for studies of transient performance because these are more computationally intensive. This paper presents a semi-empirical modeling method for compressors based on dimensionless parameters. Application to some sample compressor data is illustrated. The model equations are simple to employ and will not introduce significant stability problems when used as part of a system simulation.

The Icing Branch at NASA Glenn Research Center has funded an exploratory effort to identify requirements for developing a flight dispatcher-centered web-based icing training program that would be available for all airspace users. Through research and discussions with personnel at airlines, target areas were identified as influences on the requirements for the training system: 1 Flight dispatchers' icing related judgments and decision-making; 2 Certification, new hire and recurrent flight dispatcher training with respect to icing; 3 Icing related weather sources and the problems that flight dispatchers may have in their interpretation; 4 Pedagogical strategies (such as flight dispatcher-centered scenario-based approaches) for delivering flight dispatcher training content; and 5 Concerns/constraints with respect to web-based training for flight dispatchers.

A biaxial test procedure is used to assess the constitutive properties of polymers in tension. The constitutive constants are derived for high strain rate applications such as those associated with crashworthiness studies. The test procedure is used in conjunction with a time- and strain-dependent quasi-linear viscoelastic constitutive law consisting of a Mooney-Rivlin formulation combined with Maxwell elements. The procedure is demonstrated by describing the stress vs. strain relationship of a rubber specimen subjected to a step-relaxation input. The constitutive equation is transformed from a nonlinear convolution integral to a set of first order differential equations. These equations, with the appropriate boundary conditions, are solved numerically to obtain transient stresses in two principal directions. Material constants for use in the explicit LS-Dyna non-linear finite element code are provided.

Biomechanical data are often assumed to be doubly censored. In this paper, this assumption is evaluated critically for several previously published sets of data. Injury risk functions are compared using simple logistic regression and using survival analysis with 1) the assumption of doubly censored data and 2) the assumption of right-censored (uninjured specimens) and uncensored (injured) data. It is shown that the injury risk functions that result from these differing assumptions are not similar and that some experiments will require a preliminary assessment of data censoring prior to finalizing the experimental design. Some types of data are obviously doubly censored (e.g., chest deflection as a predictor of rib fracture risk), but many types are not left censored since injury is a force-limiting phenomenon (e.g., axial force as a predictor of tibia fracture). Guidelines for determining the censoring for various types of experiment are presented.

This paper presents a technique for developing corridors from individual subject responses contained in experimental biomechanical data sets. Force-deflection response is used as an illustrative example. The technique begins with a method for averaging human subject force-deflection responses in which curve shape characteristics are maintained and discontinuities are avoided. Individual responses sharing a common characteristic shape are averaged based upon normalized deflection values. The normalized average response is then scaled to represent the given data set using the mean peak deflection value associated with the set of experimental data. Finally, a procedure for developing a corridor around the scaled normalized average response is presented using standard deviation calculations for both force and deflection.

This paper presents an analysis of the displacement measurement of the Hybrid III 50th percentile male dummy chest in quasistatic and dynamic loading environments. In this dummy, the sternal chest deformation is typically characterized using a sliding chest potentiometer, originally designed to measure inward deflection in the central axis of the dummy chest. Loading environments that include other modes of deformation, such as lateral translations or rotations, can create a displacement vector that is not aligned with this sensitive axis. To demonstrate this, the dummy chest was loaded quasistatically and dynamically in a series of tests. A string potentiometer array, with the capability to monitor additional deflection modes, was used to supplement the measurement of the chest slider.

Strategies for the inoculation of bioreactors for long-term space missions include communities of diverse composition or, alternatively, communities of a few organisms selected for their ability to efficiently catalyze reactions of interest in the reactor. The concept of functional redundancy states that in a diverse community, several different organisms may be present that are capable of effecting processes necessary to the maintenance of the system function. The concept implies that if some members of the community are lost, others will be able to keep the system from failing in the critical reactions that take place therein. In a sewage reactor in the laboratory, a diverse community at steady state was perturbed by elimination of aeration for seven days. Chemical pools (NH4+, NO3-, dissolved O2), pH, and CO2 evolution were monitored before, during, and after the perturbation.

Studies show that the pedestrian population at high risk of injury consists of both young children and adults. The goal of this study is to gain understanding in the mechanisms that lead to injuries for children and adults. Multi-body pedestrian human models of two specific anthropometries, a 6year-old child and a 50th percentile adult male, are applied. A vehicle model is developed that consists of a detailed rigid finite element mesh, validated stiffness regions, stiff structures underlying the hood and a suspension model. Simulations are performed in a test matrix where anthropometry, impact speed and impact location are variables. Bumper impact occurs with the tibia of the 50th percentile adult male and with the thigh of the 6-year-old child. The head of a 50th percentile male impacts the lower windshield, while the 6-year-old child's head impacts the front part of the hood.

This research investigates the variation of pedestrian stance in pedestrian-automobile impact using a validated multi-body vehicle and human model. Detailed vehicle models of a small family car and a sport utility vehicle (SUV) are developed and validated for impact with a 50th percentile human male anthropometric ellipsoid model, and different pedestrian stances (struck limb forward, feet together, and struck limb backward) are investigated. The models calculate the physical trajectory of the multi-body models including head and torso accelerations, as well as pelvic force loads. This study shows that lower limb orientation during a pedestrian-automobile impact plays a dominant role in upper body kinematics of the pedestrian. Specifically, stance has a substantial effect on the subsequent impacts of the head and thorax with the vehicle. The variation in stance can change the severity of an injury incurred during an impact by changing the impact region.