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Vehicle fleet downsizing has been discussed in Europe as an aspect to reduce fuel emissions. A recently developed mathematical model was used to study the individual effects of fleet mass distribution, impact speed reductions and inherent vehicle protection on average injury and fatality rates for downsized fleets. A baseline fleet of 700-2000 kg was downsized by a) reducing all vehicle masses by 10% or 20% and b) by removing all cars heavier than 1400 or 1200 kg. The results showed that the safety can be maintained if the vehicle masses are reduced proportionally to their original mass. A higher safety level can be achieved by removing the heavier vehicles. Traffic safety can be further enhanced by impact speed reductions or by improvements of restraint systems and vehicle compatibility.

Classical blunt thoracic impacts have involved midsternal anteroposterior loadings to an upright-positioned subject. Data on the sensitivity of human cadaver and/or animal model biomechanical and injury responses to blunt loadings at different sternal locations is needed to evaluate the efficacy of current injury-potential guidelines for nonsite-specific frontal impacts. In addition, the biomechanics and injury mechanisms associated with lateral impacts constitute a subject of increasing consideration for occupant protection. Twelve anesthetized pigs were subjected to various blunt frontal or a right-side impact to assess biomechanical and injury response differences in a living animal model.

The objective of this study was to analyze rear crashes for the risk of serious injury (AIS 3+) by delta V. Rear impacts were analyzed for occupants sitting in front seats of light vehicles. Data was obtained from NASS-CDS for calendar years 1991-2004. Tow-away crashes with ≤15 mph rear delta V account for 67% of rear impacts and 15% of serious injury. Even for crashes <30 mph delta V, the risk for serious injury is only 0.24% (less than 1 per 420 exposed occupants). Risks increase for higher delta Vs. Individual cases in the 1997-2004 NASS-CDS electronic database were reviewed for serious injury in crashes with ≤15 mph delta V and ≥35 mph for light vehicles with calendar year >1996 to better understand injury mechanisms. Nine cases were available where a front-seat occupant was seriously injured in ≤15 mph rear delta V impact. Most cases involved older occupants, some of whom had stenosis of the cervical spine.

The purpose of this paper is to compare the biofidelity rating schemes of ISO/TR9790 and the NHTSA Bio Rank System. This paper describes the development of new impact response corridors being proposed for ISO/TR9790 from the results of a recent series of side-impact sled tests. The response data were analyzed by methods consistent with ISO/TR9790, including normalization by impulse-momentum analysis and the elimination of subjects that sustained six or more rib fractures. Unlike ISO/TR9790, this paper proposes the elimination of the data from tests in which the timing and the sequence of loading of the individual impact plates were inconsistent compared to other tests conducted with the same impact wall configuration.

As the driving population ages, there is a need to understand the accident patterns of older drivers. Previous research has shown that side impact collisions, usually at an intersection, are a serious problem for the older driver in terms of injury outcome. This study compares the frequency of side impact, intersection collisions of different driver age groups using state and national police-reported accident data as well as an in-depth analysis of cases from a fatal accident study. All data reveal that the frequency of intersection crashes increases with driver age. The state and national data show that older drivers have an increase frequency of intersection crashes involving vehicles crossing paths prior to the collision compared to their involvement in all crash types. When taking into account traffic control devices at an intersection, older drivers have the greatest involvement of multiple vehicle crashes at a signed intersection.

The concept of rate of onset as an injury potential index is critically discussed through the analysis of a wide range of noninjurious whole body decelerations and localized impacts. Examination of the physical data shows that extremely high rates of onset are tolerable without injury and that these levels of rate of onset are reciprocally dependent on the pulse rise time. The physical data is next discussed with reference to existing acceleration injury criteria, specifically the GSI and HIC indices. This work substantiates the conclusions that a single rate of onset tolerance level is not warranted and that rate of onset is not a proven injury potential index.

A critical performance issue in the development of any air cushion restraint system is the dichotomy that exists between the inflation rate required to meet the 30 mph frontal, rigid barrier restraint performance requirements and the effect that this parameter has on increasing the risk of deployment-induced injuries to out-of-position occupants. In general, small cars experience greater vehicle deceleration levels than large vehicles in FMVSS 208, 30 mph frontal, rigid barrier tests due to tighter packaging of their front-end components. In order to meet the FMVSS 208 performance requirements for such cars, the small car air cushion must be thicker and inflated faster than the large car air cushion. Such air cushion technology will increase the risk of life-threatening, deployment-induced injuries to out-of-position occupants of the small car.

The objective of this study was to analyze available anthropomorphic test device (ATD) responses from KARCO rear impact tests and to evaluate an injury predictive model based on crash severity and occupant weight presented by Saczalski et al. (2004). The KARCO tests were carried out with various seat designs. Biomechanical responses were evaluated in speed ranges of 7-12, 13-17, 18-23 and 24-34 mph. For this analysis, all tests with matching yielding and stiff seats and matching occupant size and weight were analyzed for cases without 2nd row occupant interaction. Overall, the test data shows that conventional yielding seats provide a high degree of safety for small to large adult occupants in rear crashes; this data is also consistent with good field performance as found in NASS-CDS. Saczalski et al.'s (2004) predictive model of occupant injury is not correct as there are numerous cases from NASS-CDS that show no or minor injury in the region where serious injury is predicted.

Belt interaction with the dummy's chest or pelvis was investigated during simulated frontal decelerations to develop a better understanding of the mechanics of belt restraint. Hyge sled tests were conducted at acceleration levels of 6-16 g's with a Part 572 dummy forward facing on an automotive bucket seat. Dynamics were compared in similar tests where the dummy was restrained by a conventional shoulder belt or belt segments attached to a modified sternum - a steel sternum with extensions for fixed belt attachments. Tests were also conducted with a conventional lap belt or belt segments fixed to an extension of the H point. Deformation characteristics of the standard and modified thorax were determined for a lateral and superior point load or a belt yoke compression of the sternum. The pelvic structure was also compressed by a lap belt. Our evaluation of test dummy dynamics indicates the following sequence of events with a conventional shoulder belt: 1.)

This report describes a series of experiments using Hexcel(TM) to limit the impact force in lateral abdominal impacts. Two hundred fourteen (214) anesthetized New Zealand White rabbits were impacted at 5 to 15 m/s using a pneumatic impactor. Injury responses from tests with a force-limiting impact interface (94 tests) were compared with the responses from tests with a rigid impact interface (120 tests) having the same level of lateral abdominal compression. The Hexcel had a length of 3 inches, the same diameter as the rigid impactor, and crushed at a constant force (pressure level of 232 kPa (33 psi)) once deformation was initiated. The results of these tests showed that the probability of serious abdominal injury did not change significantly with the Hexcel, even though peak pressures were reduced to as little as one third of their previous values.

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.

Two Highway Safety Research Institute (HSRI) dummies were tested and evaluated. Based on the analysis given, the HSI dummy should not be used for vehicle qualification testing. However, many of its components offer viable alternatives for future dummy development. The dummy was found to have inadequate biomechanical fidelity in the head, neck, and chest, although its characteristics were very promising and, as a whole, biomechanically superior to the Hybrid II. Its repeatability and reproducibility in dynamic component tests were better than the Hybrid II dummy. In particular, the HSRI friction joints were outstanding in repeatability and had a significant advantage in usability in that they do not require resetting between tests. In three-point harness and ACRS systems tests, the values of injury criteria produced by the HSRI dummy were generally lower than those obtained with the Hybrid II, especially the femur loads in the ACRS tests.

A review and analysis of existing cadaver head impact data has been conducted in this paper. The association of the Head Injury Criterion with experimental cadaver skull fracture and brain damage has been investigated, and risk curves of HIC versus skull fracture and brain damage have been developed. Limitation of the search for the maximum HIC duration to 15ms has been recommended for the proper use of HIC in the automotive crash environment.

The discovery of the mechanism of impact-induced soft tissue injury has led to our introduction of a Viscous Injury Criterion, which predicts the severity and the time of occurrence of soft tissue injury induced by impact when other criteria have failed. Human tolerance has been defined by the Viscous response, [VC], a time function generated by the instantaneous product of velocity of deformation [V(t)] and amount of compression [C(t)] of the body. [VC]max = 1.0 m/s corresponds experimentally to a 25% chance of sustaining severe thoracic injury (AIS ≥ 4) in a blunt frontal impact. A similar level of risk for critical abdominal injury (AIS ≥ 5) in a blunt frontal impact is [VC]max = 1.2 m/s. However, human tolerance is defined more completely by the probability function of injury risk versus [VC]max. The Viscous response can be evaluated in the Hybrid III anthropomorphic dummy by a straightforward analysis of the chest deflection data.

Five anesthetized porcine subjects were exposed to blunt thoracic impact using a 21 kg mass with a flat contact surface traveling at 3.0 to 12.2 m/s. The experiments were conducted to assess the appropriateness of studying in vivo mechanical and physiological response to thoracic impact in a porcine animal model. A comprehensive review of comparative anatomy between the pig and man indicates that the cardiovascular, respiratory and thoracic skeletal systems of the pig are anatomically and functionally a good parallel of similar structures in man. Thoracic anthropometry measurements document that the chest of a 50 to 60 kg pig is similar to the 50th percentile adult male human, but is narrower and deeper. Peak applied force and chest deflection are in good agreement between the animal's responses and similar impact severity data on fresh cadavers.

There are currently two accepted criteria for assessment act exposures. Our studies have shown an interaction between the deformation velocity and level of compression during impact, resulting in a greater compression tolerance for low-speed impact than for high-speed loadings. High-speed thoracic impact can cause critical or fatal injury in physiologic experiments before exceeding the acceleration or compression tolerance. The velocity-sensitive tolerance is represented by the maximum product of velocity of deformation and compression, which is derivable from the chest compression response. As the magnitude of this “viscous” response increases, the risk of serious or fatal injury increases. This paper discusses the analysis of available literature and results from our laboratory and demonstrates the need for a viscous tolerance criterion to assess chest impact protection in high-velocity impact.

Measurement of chest compression is vital to properly assessing injury risk for restraint systems. It directly relates chest loading to the risk of serious or fatal compression injury for the vital organs protected by the rib cage. Other measures of loading such as spinal acceleration or total restraint load do not separate how much of the force is applied to the rib cage, shoulders, or lumbar and cervical spines. Hybrid III chest compression is biofidelic for blunt impact of the sternum, but is “stiff” for belt loading. In this study, an analysis was conducted of two published crash reconstruction studies involving belted occupants. This provides a basis for comparing occupant injury risks with Hybrid III chest compression in similar exposures. Results from both data sources were similar and indicate that belt loading resulting in 40 mm Hybrid III chest compression represents a 20-25% risk of an AIS≥3 thoracic injury.

Injury risk curves for SID-IIs thorax and abdomen rib deflections proposed for future NCAP side impact evaluations were developed from tests conducted with the SID-IIs FRG. Since the floating rib guide is known to reduce the magnitude of the peak rib deflections, injury risk curves developed from SID-IIs FRG data are not appropriate for use with SID-IIs build level D. PMHS injury data from three series of sled tests and one series of whole-body drop tests are paired with thoracic rib deflections from equivalent tests with SID-IIs build level D. Where possible, the rib deflections of SID-IIs build level D were scaled to adjust for differences in impact velocity between the PMHS and SID-IIs tests. Injury risk curves developed by the Mertz-Weber modified median rank method are presented and compared to risk curves developed by other parametric and non-parametric methods.

Crash-test-data on local longitudinal and shear stiffness of the vehicle front is needed to estimate impact severity from car deformation in offset or pole impacts, and to predict vehicle acceleration and compartment intrusion in car-to-car crashes. Repeated full frontal crash-tests were carried out with a load-cell barrier to determine the local longitudinal stiffness with increasing crush. Repeated off-set tests were run to determine shear stiffness. Two single high-speed tests (full frontal and offset) were carried out and compared to the repeated tests to determine the rate sensitivity of the front structure. Four repetitions at 33.4 km/h provided equivalent energy absorption to a single 66.7 km/h test, when rebound was considered. Power-train inertial effects were estimated from highspeed tests with and without power-train. Speed effects averaged 2% per [m/s] for crush up to power-train impact, and post-crash measurements were a reasonable estimate of front-structure stiffness.

Objective: A friction rollover test was conducted as part of a rollover sensing project. This study evaluates vehicle and occupant responses in the test. Methods: A flat dolly carried a Saab 9-3 sedan laterally, passenger-side leading to a release point at 42 km/h (26 mph) onto a high-friction surface. The vehicle was equipped with roll, pitch and yaw gyros near the center of gravity. Accelerometers were placed at the vehicle center tunnel, A-pillar near the roof, B-pillar near the sill, suspension sub-frame and wheels. Five off-board and two on-board cameras recorded kinematics. Hybrid III dummies were instrumented for head and chest acceleration and upper neck force and moment. Belt loads were measured. Results: The vehicle release caused the tires and then wheel rims to skid on the high-friction surface. The trip involved roll angular velocities >300 deg/s at 0.5 s and a far-side impact on the driver’s side roof at 0.94 s. The driver was inverted in the far-side, ground impact.