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The dilemma of using a shoulder belt force limiter with a 3-point belt system is selecting a limit load that will balance the reduced risk of significant thoracic injury due to the shoulder belt loading of the chest against the increased risk of significant head injury due to the greater upper torso motion allowed by the shoulder belt load limiter. However, with the use of air bags, this dilemma is more manageable since it only occurs for non-deploy accidents where the risk of significant head injury is low even for the unbelted occupant. A study was done using a validated occupant dynamics model of the Hybrid III dummy to investigate the effects that a prescribed set of shoulder belt force limits had on head and thoracic responses for 48 and 56 km/h barrier simulations with driver air bag deployment and for threshold crash severity simulations with no air bag deployment.

The Hybrid III dummy is an anthropomorphic (humanlike) test device, generally used in crashworthiness testing to assess the extent of occupant protection provided by the vehicle structure and its restraint systems in the event of vehicle crash. Lumped-parameter analytical models are commonly used to simulate the dummy response. These models, by virtue of their limited number of degrees of freedom, can neither represent accurate three-dimensional dummy geometry nor detailed structural deformations. In an effort to improve the state-of-the-art in analytical dummy simulations, a set of finite element models of the Hybrid III dummy segments - head, neck, thorax, spine, pelvis, knee, upper extremities and lower extremities - were developed. The component models replicated the hardware geometry as closely as possible. Appropriate elastic material models were selected for the dummy “skeleton”, with the exterior “soft tissues” represented by viscoelastic materials.

A study was conducted by General Motors at its crash test facility located at the Milford Proving Ground. The intent of this study was to expand upon the currently available research regarding the safety belt buckle environment during full scale planar crash tests. Buckle accelerations and webbing tensions were measured and recorded to characterize, in part, buckle responses in a crash environment. Previous studies have focused primarily on the component level testing of safety belt buckles. The crash tests included a variety of vehicles, impact types, seating positions, Anthropomorphic Test Devices (ATDs), impact speeds, and impact angles. Also included were various safety belt restraint systems and pretensioner designs. This study reports on data recorded from 100 full scale crash tests with 180 instrumented end release safety belt buckles. Acceleration measurements were obtained with tri-axial accelerometers mounted onto the buckles.

This paper describes an analytical method to predict the sensor closure time for an airbag (Supplemental Inflatable Restraint - SIR) system in frontal impacts. The analytical tools used are the explicit finite element code, an in-house sensor closure time prediction program, and a full vehicle finite element model. Nodal point information obtained from the full vehicle finite element simulation is used to predict the sensor closure time of the airbag system. This analytical method can provide the important crash signature information for a SIR system development of a new vehicle program. In this paper, 0-degree frontal impacts at four different impact speeds with two different bumper energy absorption systems are studied using the non-linear finite element computer program DYNA3D. It is concluded that this analytical method is very useful to predict the SIR sensor closure time.

Although rollover crashes represent a small fraction (approximately 3%) of all motor vehicle crashes, they account for roughly one quarter of crash fatalities to occupants of cars, light trucks, and vans (NHTSA Traffic Safety Facts, 2004). Therefore, the National Highway Traffic Safety Administration (NHTSA) has identified rollover injuries as one of its safety priorities. Motor vehicle manufacturers are developing technologies to reduce the risk of injury associated with rollover collisions. This paper describes the development by General Motors Corporation (GM) of a suite of laboratory tests that can be used to develop sensors that can deploy occupant protection devices like roof rail side air bags and pretensioners in a rollover as well as a discussion of the challenges of conducting this suite of tests.

This paper summarizes the results of tests conducted with anesthetized animals that were exposed to a wide range of passenger inflatable restraint cushion forces for a variety of impact sled - simulated accident conditions. The test configurations and inflatable restraint system concepts were selected to produce a broad spectrum of injury types and severities to the major organs of the head, neck and torso of the animals. These data were needed to interpret the significance of the responses of an instrumented child dummy that was being used to evaluate child injury potential of the passenger inflatable restraint system being developed by General Motors Corporation. Injuries ranging from no injury to fatal were observed for the head, neck and abdomen regions. Thoracic injuries ranged from no injury to critical, survival uncertain.

This paper presents the results of a series of over 30 impact sled simulations of racing car frontal crashes conducted as part of the GM Motorsports Safety Technology Research Program. A Hyge™ impact sled fitted with a simulated racing car seat and restraint system was used to simulate realistic crash loading with a mid-size male Hybrid III dummy. The results of tests, in the form of measured loads, displacements, and accelerations, are presented and comparisons made with respect to the levels of these parameters seen in typical passenger car crash testing and to current injury threshold values.

A primary concern in the development of a passenger inflatable restraint system is the possibility that a child could be in the path of the deploying cushion either due to initial position at the time of an accident or due to precrash braking accompanying an accident. Previous studies by General Motors and Volvo have indicated that serious injuries to children are possible if the cushion/child interaction forces are not controlled by system design. This paper describes an instrumented child dummy which was developed to provide measurements of the various cushion/child interaction forces. An analysis is given describing the types of injuries which could be associated with the various types of interaction forces. These results were used to develop appropriate dummy instrumentation for indicating the severity of the cushion/child interaction. A description of the modifications made to an existing three-year-old child dummy are described.

In this paper, the concept of ridedown analysis is extended to provide the total occupant energy and ridedown energy as functions of time. The difference between the total occupant energy and the energy absorbed by the front structure represents the energy which is dissipated by deforming the components of the restraint system. This analysis allows an improved understanding of the restraint system as a whole, and how its components interact with each other and with the front structure of the car to dissipate the occupant's energy throughout the crash event.

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.

An analysis is presented that was used to interpret the significance of response measurements made with a specially instrumented, 3-year-old child dummy that was used to evaluate child injury potential of the second-generation, passenger inflatable restraint system that was being developed by General Motors Corporation. Anesthetized animals and a specially instrumented child dummy, both 3-year-old child surrogates, were exposed to similar inflating-cushion, simulated collision environments. The exposure environments were chosen to produce a wide spectrum of animal injury types and severities, and a corresponding broad range of child dummy responses. For a given exposure environment, the animal injury severity ratings for the head, neck, thorax and abdomen are paired with dummy response values corresponding to these body regions.

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.

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.

Fatal crash circumstances for 48 belted female drivers were studied in-depth and compared to those of 83 belted male drivers in a similar population of vehicles. Women had a higher incidence of crashes on slippery roads, during lane changes and passing maneuvers than men who had a higher rate of aggressive driving and speed related crashes (χ2 = 10.47, p < 0.001). Driver-side damage was significantly more frequent in female than male crashes (χ2 = 5.74, p < 0.025) and women had a higher fraction of side impacts (45.9% v 31.4%) and crashes during daylight (87.0% v 72.3%, χ2 = 3.65, p < 0.05) than men. Women also had a higher fraction of potentially avoidable crashes than men (57.5% v 39.0%) and a lower involvement related to aggressive driving (10.6% v 25.6%). These differences were statistically significant (χ2 = 5.41, p < 0.025).

Aspirating airbag modules are unique from other designs in that the gas entering the airbag is a mixture of inflator-delivered gas and ambient-temperature air entrained from the atmosphere surrounding the module. Today's sophisticated computer simulations of an airbag deployment typically require as input the mass-flow rate, chemical composition and thermal history of the gas exiting the canister and entering the airbag. While the mass-flow rate and temperature of the inflator-delivered gas can be obtained from a standard tank test, information on air entrainment into an aspirated canister is limited. The purpose of this study is to provide quantitative information about the aspirated mass-flow rate during airbag deployment. Pressure and velocity measurements are combined with high-speed photography in order to gain further insight into the relationship between the canister pressure, the rate of cabin-air entrainment and the airbag deployment.

A deformable finite element dummy model was used to simulate air bag interaction with in-position passenger side occupants in frontal vehicle crash. This dummy model closely simulates the Hybrid III hardware with respect to geometry, mass, and material properties. Test data was used to evaluate the validity of the model. The calculated femur loads, chest acceleration and head acceleration were in good agreement with the test data. A semi-rigid dummy model (with rigid chest) was derived from the deformable dummy to improve turnaround time. Simulation results using the semi-rigid dummy model were also in reasonable agreement with the test data. For comparison purpose, simulations were also performed using PAMCVS, a hybrid code which couples the finite element code PAMCRASH with the rigid body occupant code. The deformable dummy model predicted better chest acceleration than the other two models.

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).

The air bag safety issues became evident in 1995 and other factors have conjoined to change the climate regarding motor vehicle safety. Traditionally, motor vehicle safety issues have been evaluated based upon the effects upon average adult males. The new climate requires consideration of the effects on persons of differing size and gender. By including consideration of children and women, rulemaking and the applied technologies are able to better optimize safety than is the case when rules are focused only on the average adult male. Automotive electronics serves a key role in the migration from a one-size-fits- all protection to a more customized protection for a variety of occupants. The enhancements have been the most prominent in the area of sensing, be it the sensing and characterization of the crash itself, or the sensing and characterization of occupants in the vehicle.

An objective, biomechanically based assessment is made of the risks of life-threatening brain injury of frontal crash test results. Published 15 ms HIC values for driver and right front passenger dummies of frontal barrier crash tests conducted by Transport Canada and NHTSA are analyzed using the brain injury risk curve of Prasad and Mertz. Ninety-four percent of the occupants involved in the 30 mph, frontal barrier compliance tests had risks of life-threatening brain injury less than 5 percent. Only 3 percent had risks greater than 16 percent which corresponds to 15 ms HIC > 1000. For belt restrained occupants without head contact with the interior, the risks of life-threatening brain injury were less than 2 percent. In contrast, for the more severe NCAP test condition, 27 percent of the drivers and 21 percent of the passengers had life-threatening brain injury risks greater than 16 percent.

This study is an extension of previous work on driver air bag deployment loads which used the mid-size male Hybrid Ill dummy. Both small female and mid-size male Hybrid Ill dummies were tested with a range of near-positions relative to the air bag module. These alignments ranged from the head centered on the module to the chest centered on the module and with various separations and lateral shifts from the module. For both sized dummies the severity of the loading from the air bag depended on alignment and separation of the dummy with respect to the air bag module. No single alignment provided high responses for all body regions, indicating that one test at a typical alignment cannot simultaneously determine the potential for injury risk for the head, neck, and torso. Based on comparisons with their respective injury assessment reference values, the risk of chest injury appeared similar for both sized dummies.