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The protection of a vehicle occupant in a frontal crash is a combination of vehicle front structural design and occupant restraint design. Once chosen and manufactured, these design features must interact with a wide variety of structural characteristics in potential crash partners. If robust, the restraint design will provide a high level of protection for a wide variety of crash conditions. This paper examines how robust a given restraint system is for occupant self-protection and how frontal design can improve the restraint performance of potential crash partners, thus improving their restraint robustness as well. To examine restraint robustness in self protection, the effect of various vehicle deceleration characteristics on occupant injury potential is investigated for a given restraint design. A MADYMO model of a 1996 Taurus interior and its restraint system with a Hybrid III 50th percentile male dummy are simulated and subjected to 650 crash pulses taken during 25 years of U.S.

Since 1994, the New Car Assessment Program (NCAP) of the National Highway Traffic Safety Administration (NHTSA) has compiled upper neck loads for the belt and air bag restrained 50th percentile male Hybrid III dummy. Over five years from 1994 to 1998, in frontal crash tests, NCAP collected upper neck data for 118 passenger cars and seventy-eight light trucks and vans. This paper examines these data and attempts to assess the potential for neck injury based on injury criteria included in FMVSS No. 208 (for the optional sled test). The paper examines the extent of serious neck injury in real world crashes as reported in the National Automotive Sampling System (NASS). The results suggest that serious neck injuries do occur at higher speeds for crashes involving occupants restrained by belts in passenger cars.

This paper describes ongoing research conducted by the National Highway Traffic Safety Administration (NHTSA) to evaluate the potential of safety restraints on large school buses. School bus transportation is one of the safest forms of transportation in the United States. Large school buses provide protection because of their visibility, size, and weight, as compared to other types of motor vehicles. Additionally, they are required to meet minimum Federal Motor Vehicle Safety Standards (FMVSS) mandating compartmentalized seating, emergency exits, roof crush and fuel system integrity, and minimum bus body joint strength.

A research program was initiated to evaluate the performance of prototype dual stage passenger air bags in terms of both restraint system performance and deployment aggressivity for different size occupants. Variations in inflator partitions, vent hole diameter sizes, and deployment timing were examined. High speed unbelted sled tests were conducted with both 50th percentile male and 5th percentile female Hybrid III adult dummies at 48 kmph; and belted sled tests were conducted at 56 kmph. Low risk deployment tests with child dummies were conducted to evaluate air bag aggressivity. Overall, it was concluded that the dual stage air bag systems under evaluation had improved performance over the baseline single stage systems in terms of providing high speed protection while reducing aggressivity to out-of-position occupants; however, some dual stage systems may require additional occupant detection methodologies to suppress or control inflation.

NHTSA uses a variety of computer modelling techniques to develop and evaluate test methods and mitigation concepts, and to estimate safety benefits for many of NHTSA's research activities. Computer modeling has been particularly beneficial for estimating safety benefits where often very little data are available. Also modeling allows researchers to augment test data by simulating crashes over a wider range of conditions than would otherwise be feasible. These capabilities are used for a wide range of projects from school bus to frontal, side, and rollover research programs. This paper provides an overview of these activities. NHTSA's most extensive modeling research involves developing finite element and articulated mass models to evaluate a range of vehicles and crash environments. These models are being used to develop a fleet wide systems model for evaluating compatibility issues.

This paper describes computer crash simulations performed by the National Highway Traffic Safety Administration (NHTSA) under the current research and testing activities on large school bus safety restraints. The simulations of a frontal rigid barrier test and comparative dynamic sled testing for compartmentalization, lap belt, and lap/shoulder belt restraint strategies are presented. School bus transportation is one of the safest forms of transportation in the United States. School age children transported in school buses are safer than children transported in motor vehicles of any other type. Large school buses provide protection because of their size and weight. Further, they must meet minimum Federal motor vehicle safety standards (FMVSSs) mandating compartmentalized seating, improved emergency exits, stronger roof structures and fuel systems, and better bus body joint strength.

An upgrade of EUROSID-1, the side impact dummy used in the European Union Side Impact Directive 96/EC/27, was recently developed by TNO to address dummy response issues raised by industrial and governmental bodies, in particular, the flat-top anomaly in the rib deflections. NHTSA is evaluating the ES-2 dummy, the upgraded EUROSID-1, to assess its performance in the FMVSS 214 test configuration. This paper presents results from NHTSA's testing of the ES-2 including high mass pendulum impactor tests using three proposed rib designs, biofidelity sled tests comparing the ES-2 and U.S. SID, and full-scale side impact tests.

A summary of the efforts of the Biomechanics Working Group to complete the task given to it by the International Harmonized Research Activities Steering Committee to determine specifications for a Universal Side Impact Anthropomorphic Test Devices is presented. Topics discussed are the nature of the world side impact problem, the anthropometric characterization of the world population at risk, dummy impact response specifications, and necessary and appropriate injury criteria and performance levels.

The Isodamp damping material (also known as Navy Damp) used in the ribs of current crash test dummies provides human-like damping to the thorax under impact. However, the range of temperature over which it can be used is very small. A new rib design using laminates of steel, fiberglass, and commercially available viscoelastic material has been constructed. Load-deflection response and hysteresis of the laminated ribs were compared with corresponding conventional ribs fabricated from steel and Isodamp. Impact tests were conducted on laminated and conventional ribs at 18.5° C, 22.2° C and 26.6° C. Results indicate that the response of the laminated ribs is essentially the same as that of the ribs with Isodamp at 22.2° C, which is the operating temperature of the conventional ribs. The variation in the impact response of the newly developed laminated ribs in the temperature range of 18.5° C to 26.6° C was less than 10%.

Injuries to the thorax and abdomen comprise a significant percentage of all occupant injuries in motor vehicle accidents. While the percentage of internal chest injuries is reduced for restrained front-seat occupants in frontal crashes, serious skeletal chest injuries and abdominal injuries can still result from interaction with steering wheels and restraint systems. This paper describes the design and performance of prototype components for the chest, abdomen, spine, and shoulders of the Hybrid III dummy that are under development to improve the capability of the Hybrid III frontal crash dummy with regard to restraint-system interaction and injury-sensing capability.

A proposed modification to the Hybrid III 50th percentile male dummy upper femur appears to reduce the chest response problems resulting from femur-pelvis interaction in test exposures more severe than Standard No. 208 testing. When compared to overall repeatability of tests, the modification did not change other dummy response measurements appreciably. The femur-pelvis interaction problem, referred to as “hip lock”, was thought to occur in certain vehicles when the femurs of a passenger side dummy impacting only an air bag bottomed out against the pelvis structure. If metal-to-metal contact occurred, excessive load could be transferred to the chest, leading to elevated chest responses. The most pertinent signs of hip lock occurring appear to be a large, sharply pointed z chest acceleration, and a distinct positive component of the lumbar spine z force following the main negative component.

Locations of key body segments of Hybrid III dummies used in FMVSS 208 compliance tests and NCAP tests were measured and subjected to statistical analysis. Mean clearance dimensions and their standard deviations for selected body segments of driver and passenger occupants with respect to selected vehicle surfaces were determined for several classes of vehicles. These occupant locations were then investigated for correlation with impact responses measured in crash tests and by using a three dimensional human-dummy mathematical model in comparable settings. Based on these data, the importance of some of the clearance dimensions between the dummy and the vehicle surfaces was determined. The study also compares observed Hybrid III dummy positions within selected vehicles with real world occupant positions reported in published literature.

The National Highway Traffic Safety Administration has initiated research to develop performance specifications for dummy-based accelerometers in the crash test environment, and to provide criteria for defining and establishing equivalent performance among accelerometers from different manufacturers. These research efforts are within the general guidelines on transducer equivalency outlined in the current revision of the Society of Automotive Engineers recommended practice, Instrumentation for Impact Test, SAE 211/2 March 1995. Representative data from vehicle crash and component level tests have been analyzed to determine the acceleration levels and frequency content in a realistic dynamic environment for dummy-based accelerometers.

This paper addresses the protection of occupants in light vehicles. It presents data and techniques for identifying and measuring potential crashworthiness improvements that would mitigate injuries to occupants striking frontal interior components such as the steering wheel, instrument panel and windshield. Both restrained and unrestrained occupants can be injured by frontal interior components in crashes. The focus of this paper is on the unrestrained occupant. However, performance criteria and associated countermeasures will have to be developed considering the differences in the mechanisms of injury to both the restrained and unrestrained occupants. Work on the restrained occupant and the similarities and differences between both conditions remains to be considered. The paper presents information on the magnitude and types of injuries received from frontal interior components and on how the performance of these components and the vehicle structure affect the resultant injuries.

The injury reducing effectiveness of child safety seats in frontal crashes was evaluated, based on 36 frontal or oblique sled tests run with two or more GM three-year-old dummies in the simulated passenger compartment of a car. Unrestrained, correctly restrained and incorrectly restrained dummies were tested at the range of speeds where most nonminor injuries occur (15-35 mph). Accident data from NHTSA files were used to calibrate a relationship between the front-seat unrestrained dummies' HIC and unrestrained children's risk of serious head injuries; also between torso g's and the risk of serious torso injuries. These relationships were used to predict injury risk for the restrained children as a function of crash speed and to compare it to the risk for unrestrained children. The sled test analysis predicted that the 1984 mix of correctly and incorrectly used safety seats reduced serious injury risk by 40 percent relative to the unrestrained child, in frontal crashes.

The frontal crash standard in the USA specifies that the full front of a vehicle impact a rigid barrier. Subsequently, the European Union developed a frontal crash standard that requires 40 percent of the front of a vehicle to impact a deformable barrier. The present study conducted paired crashes of vehicles using the full-frontal barrier procedure and the 40 percent offset deformable barrier procedure. In part, the study was to examine the feasibility of adding an offset test procedure to the frontal crash standard in the USA. Frontal-offset and full-frontal testing was conducted using both the mid-size (50th percentile male Hybrid III) and the small stature (5th percentile female Hybrid III) dummies. Five vehicle models were used in the testing: Dodge Neon, Toyota Camry, Ford Taurus, Chevrolet Venture and Ford Contour. In the crash tests, all dummies were restrained with the available safety belt systems and frontal air bags.

The air bag has proven effective in reducing fatalities in frontal crashes with estimated decreases ranging from 11% to 30% depending on the size of the vehicle [IIHS-1995, Kahane-1996]. At the same time, some air bag designs have caused fatalities when front-seat passengers have been in close proximity to the deploying air bag [Kleinberger-1997]. The objective of this study was to develop an accurate and repeatable out-of-position test fixture to study the deployment of air bags into out-of-position occupants. Tests were performed with a 5th percentile female Hybrid III dummy and studied air bag loading on the thorax using draft ISO-2 out-of-position (OOP) occupant positioning. Two different interpretations of the ISO-2 positioning were used in this study. The first, termed Nominal ISO-2, placed the chin on the steering wheel with the spine parallel to the steering wheel.

The Eurosid-1 dummy was subjected to a series of lateral and oblique pendulum impacts to study the anomalous “flat-top” thorax deflection versus time-histories observed in full-scale vehicle tests. The standard Eurosid-1, as well as two different modified versions of the dummy, were impacted at 6 different angles from -15 to +20 degrees (0 degrees is pure lateral) in the horizontal plane. The flat-top deflections were observed in the tests with the standard Eurosid-1, while one of the modified versions reduced the flat-top considerably. Full scale vehicle tests with the standard and modified Eurosid-1 suggest similar reductions. A second series of tests was conducted on the modified Eurosid-1 to investigate the effect of door surface friction on the shoulder rotation and the chest deflection. The data suggested that increasing the friction on the door surface impeded shoulder rotation and ultimately reduced the chest deflection in the Eurosid-1.

Since model year 1983, one hundred and seventy five light trucks, vans, and sport utility vehicles (LTVs) have been included in the New Car Assessment Program (NCAP) frontal crash tests. In this frontal test, vehicles are crashed at 35 mph such that the entire front impacts against a rigid, fixed barrier. Instrumented anthropometric dummies are placed in the driver and right front passenger seats. Accelerometers are placed on the vehicle to record the response of the structure during the crash. A number of recent papers have examined the compatibility of LTVs and cars in vehicle-to-vehicle collisions. The studies in these papers, generally, consider three factors for vehicle-to-vehicle compatibility: (1) mass, (2) stiffness, and (3) geometry. On June 5, 1998, Transport Canada and the National Highway Traffic Safety Administration held a forum entitled “Transport-NHTSA International Dialogue on Vehicle Compatibility,” in Windsor, Canada.