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Technical Paper

Analysis of the Pelvis-Chest Interactions in Hybrid III

The interaction ILLEGIBLEf the chest of the Hybrid III dummy with the air bag restrILLEGIBLEt system during a crash is complex. Forces applied to one ILLEGIBLEmponent of the dummy can generate an unexpected response in a distal part. Motion, both linear and angular, of the pelvis during impact can create an enigmatic spike in the acceleration of the chest. Because significant changes in the chest acceleration response can affect the development of an airbag system, this pelvis-chest interaction is cause for concern. The factors that appear to affect the chest acceleration spike as a result of the pelvis-chest interaction are: the mass moment of inertia of the pelvis, the interaction of the pelvis with the femur, the characteristic of the lumbar spine, and the differential velocity of the pelvis with respect to the chest.
Technical Paper

Energy-Absorbing Polyurethane Foam to Improve Vehicle Crashworthiness

Federal legislation mandates that automotive OEMS provide occupant protection in collisions involving front and side impacts This legislation, which is to be phased-in over several years, covers not only passenger cars but also light-duty trucks and multipurpose passenger vehicles (MPVs) having a gross vehicle weigh rating (GVWR) of 8,500 lb (3,850 kg) or less. During a frontal impact, occupants within the vehicle undergo rapid changes in velocity. This is primarily due to rapid vehicle deceleration caused by the rigid nature of the vehicle's metal frame components and body assembly. Many of today's vehicles incorporate deformable, energy-absorbing (EA) structures within the vehicle structure to manage the collision energy and slow the deceleration which in turn can lower the occupant velocity relative to the vehicle. Occupant velocities can be higher in light-duty trucks and MPVs having a full-frame structure resulting in increased demands on the supplemental restraint system (SRS).
Technical Paper

Inadvertent Air Bag Sensor Testing for Off-Road Vehicles

This paper presents the development of a test procedure for evaluation of inadvertent deployment of air bags. The methodology and early development of the procedure is discussed along with additional criteria thought to be required for trucks and sport utility vehicles. Tests conducted address severe off-road use in relation to air bag sensing systems. Data is collected from accelerometers. After worst case test conditions are identified (examples include rough road, snow plowing and jerk towing events), the data is analyzed and comparisons for design decisions can be made.
Technical Paper

Comparison of Energy Management Materials for Head Impact Protection

Energy management materials are widely used in automotive interiors in instrument panel, knee bolster, and door absorber applications to reduce the risk of injury to an occupant during a crash. Automobile manufacturers must meet standards set by the National Highway Traffic Safety Administration (NHTSA) that identify maximum levels of injury to an occupant. The recent NHTSA upgrade to the Federal Motor Vehicle Safety Standard (FMVSS) 201 test procedure(1) for upper interior head impact protection has prompted energy management materials' use in several new areas of affected vehicles. While vehicle evaluations continue, results to date show that energy management foams can be effective in reducing the head injury criterion [HIC(d)] to acceptable government and OEM levels.
Technical Paper

Fundamental Studies of Polyurethane Foam for Energy Absorption in Automotive Interiors

This paper describes and characterizes energy-absorbing polyurethane foam as exemplified foam made with Bayfill EA systems. This paper emphasizes its use for automotive passive restraint systems. Static and dynamic properties will be presented. In addition the effect of velocity, weight, density, and vehicle environment on energy absorption will be discussed. RECENT federal requirements for the safety of occupants in automobiles has prompted the industry to investigate light weight and low cost materials for energy management. The use of passive restraints in interiors, i.e. air-bags, has necessitated the development of energy-absorbing instrument panels (IP) for passenger cars and multi-purpose vehicles. When air-bags are deployed in a collision the passenger tends to slide under the bag impacting the knee into the instrument panel. Foam as an energy absorbing material has played an important role in the development of knee bolsters for these interiors.
Technical Paper

Reliability Estimation and Failure Prediction of Vehicle Systems and Components

For designing new products or developing new specifications, the reliability performance of systems and components experienced by the customer provides invaluable information for the engineer. This information, not only provides for the visibility of reliability requirements, but also an awareness of potential degradation of the systems and components during its life cycle. In this paper, a method is presented for predicting vehicle system and component reliability from vehicle fleet repair data. This method combines sampling stratification, computer data analysis and statistical modeling techniques into a reliability analysis procedure to provide reliability prediction. Specifically, published vehicle fleet data was used to provide the basis for predicting the vehicle system and component reliability at any mileage level.
Technical Paper

Statistical Decision Making in FMVSS Testing

This paper presents a method of accounting for sample variability and sample size in establishing the acceptable bogey levels. The technique makes use of the statistical tolerance theory which accounts for the variability of the sample mean and standard deviation by determining a K-factor adjusted for sample size. The result is a tolerance that is reasonably assumed to cover a specified fraction of the population of parts. The technique, although not as simple as a fixed bogey, does discriminate between designs with different levels of energy management robustness.
Technical Paper

A Progress Report on Electromagnetic Activity of Motor Vehicle Manufacturer's Association

Starting in 1965 and continuing through 1972, the Radio Committee of the Motor Vehicles Manufacturers Association (MVMA) has been the coordinator of a number of electromagnetic research projects. These investigations have included extensive applications of the updated SAE Standard, Measurement of Electromagnetic Radiation From Motor Vehicles (20-1000 MHz)-SAE J551a. Furthermore, there were joint testing programs with the Electronic Industries Association which encompassed measuring degradation in the performance of Land Mobile Radio Service receivers resulting from varying levels of impulsive-type radiation from motor vehicles. In addition, efforts were expended in using statistical approaches for testing a number of hypotheses covering a conversion of impulsive vehicle noise data to the interference potential to Land Mobile receivers.
Technical Paper

A Basic Study of “Energy-Absorbing” Vehicle Structure and Occupant Restraints by Mathematical Model

Simplified mathematical modeling has been employed to investigate the relationship between automobile forestructure energy absorption and the restraint loads applied to passengers during a 30 mph barrier collision. A two-massmodel was developed and validated to compute restraint loading from a given passenger compartment deceleration. The effect of various deceleration curves, representing forestructure modifications, is reported. A “constant force” restraint system is also evaluated.
Technical Paper

Evaluation of Impact Test Accelerations: A Damage Index for the Head and Torso

The head Severity Index concept has attracted widespread attention in the automotive industry. This index is intended to estimate human survivability in a systematic way without relying on judgment values. It is employed for evaluating the probability of internal head injury for those indeterminate conditions where the human tolerance limits are not clearly defined. This paper discusses a damage index which is believed to be superior to the current Severity Index in several respects: 1. The concept is applicable to internal injuries of the torso as well as the head. 2. It is felt to describe the actual damage mechanism more directly. 3. It fits the Wayne State head tolerance curve better than the Severity Index. 4. It is suitable for analyzing impact pulses of any time duration. Examples cited in this paper include rocket sled exposures (250 ms duration) down to severe head impacts (5 ms duration). 5. It is more convenient to employ.
Technical Paper

The First Standard Automotive Crash Dummy

The SAE Recommended Practice J963 “Anthropomorphic Test Device for Dynamic Testing” describes a standard 50th percentile adult male anthropomorphic test dummy. For nearly three years the Crash Test Dummy Task Force worked with the limited data available in selecting values for the body dimensions and ranges of motion. The data for specifying the values of mass distribution were developed experimentally as was a test procedure for determining the dynamic spring rate of the thorax.
Technical Paper

A Procedure for Measuring Instrument Panel Visibility

A procedure has been developed for measuring the relative visibility of automotive instrument panel graphics and components. Through use of a Luckiesh-Moss Visibility Meter, discreet values of visibility can be assigned to visual targets and related to driver reaction time. Also, eyes off the road lapsed time boundaries may be established which will define visibility requirements necessary to serve the total driver population. These requirements can be translated into meaningful guidelines or standards for visibility attributes such as size, shape, color, contrast, and position of graphics, controls, and indicators. How visibility measurements are made and interpreted and the visibility measuring facility are discussed in this paper.
Technical Paper

Computer Aided Design Analysis of Instrument Panel Impact Zone

In anticipation of complying with European standards for impact protection, an instrument panel design was analyzed to determine A. impact zone boundaries B. impact test velocitiesfor the head of a front seat passenger. Chrysler computer aided design (C.A.D.) surfacing capabilities were utilized in the solution. Early knowledge of impact zone location is important to intelligent design decisions; knowledge of impact velocities aids in performing compliance testing.
Technical Paper

Laboratory Test Device for the Optimization of Seat Belt System Component Design and Installation Geometry

A laboratory test fixture was designed and built to simulate seat belt assembly installations. The anchor positions of the retractor and pillar loop, and the engaged or free-hanging position of the latchplate can be varied to either simulate a vehicle's seat belt system geometry, or to optimize a proposed geometry. The required retraction forces for a simulated geometry are determined by replacing the retractor action with a motorized load transducer that measures the force required to stow the latchplate. The pillar loop, webbing, latchplate, and their relative positions can be varied until the minimum retraction force that successfully stores the latchplate is determined. The geometry of such a condition can then be applied to future designs of seat belt assembly components and their anchor positions.
Technical Paper

How Seat Design Characteristics Affect Impact Injury Criteria

The seat can play an important part in improving occupant safety during a car impact. This paper discusses research done to determine how characteristics of seat design affect occupant safety. Impact simulator tests have been run which determine how variation of five specific seat characteristics affect FMVSS 208 occupant injury criteria. These tests simulated a 48.3 km/h (30 mi/h) frontal Oarrier impact using a 50th percentile male anthropomorphic device restrained by a two-point passive shoulder belt system. The five seat characteristics tested were the following: 1) Seat Frame Angle, 2) Seat Frame Structure, 3) H-Point Distance Above the Seat Frame, 4) Energy Absorption of the Seat Frame, and 5) Seat Cushion Foam Firmness. Test results show that the first characteristic can improve all injury criteria. The other four will improve some injury criteria at the expense of others.
Technical Paper

Digital Recording of Vehicle Crash Data

This paper discusses the development and implementation of a 16 channel data acquisition system for high “G” impact testing which includes a self-contained, on-board data acquisition unit, a programmer-exerciser and debriefing subsystems. The microprocessor controlled, on-board unit contains all signal conditioning, A/D conversion hardware and logic to store 4K 12 bit samples of data per channel. This unit will debrief into an oscilloscope, a desk-top computer or a large disk-based minicomputer system. Advantages over previous systems include the elimination of costly hardware (such as umbilical cables and recorders), and a reduction in pre-test preparation and data processing time.
Technical Paper

Development of a Rubber-Like Headform Skin Model for Predicting the Head Injury Criterion (HIC)

This paper describes the development of a rubber-like skin Finite Elements Model (FEM) for the Hybrid III headform and an experimental method to determine its material properties. The finite element modeling procedures, using material parameters derived from tests conducted on the headform skin (rubber) material, are described. Dynamic responses and computations of HIC using the developed headform model show that an Elastic-Plastic Hydrodynamic (EPH) material model of the rubber can be used for headform impact simulations. The results obtained from the headform simulation using an EPH rubber material model and drop tower tests of the headform on both a rigid and a deformable structure will be compared, in order to show the applicability of the EPH model.