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Technical Paper

Evaluation of the Field Relevance of Several Injury Risk Functions

An evaluation of the four injury risk curves proposed in the NHTSA NCAP for estimating the risk of AIS≻=3 injuries to the head, neck, chest and AIS≻=2 injury to the Knee-Thigh-Hip (KTH) complex has been conducted. The predicted injury risk to the four body regions based on driver dummy responses in over 300 frontal NCAP tests were compared against those to drivers involved in real-world crashes of similar severity as represented in the NASS. The results of the study show that the predicted injury risks to the head and chest were slightly below those in NASS, and the predicted risk for the knee-thigh-hip complex was substantially below that observed in the NASS. The predicted risk for the neck by the Nij curve was greater than the observed risk in NASS by an order of magnitude due to the Nij risk curve predicting a non-zero risk when Nij = 0. An alternative and published Nte risk curve produced a risk estimate consistent with the NASS estimate of neck injury.
Technical Paper

Effects of Shoulder Belt Limit Forces on Adult Thoracic Protection in Frontal Collisions

Three-point restraint systems have been installed in vehicles since the early 1960s. However, it wasn't until the automatic protection rule became effective for 1987 Model Year vehicles that manufacturers began installing 3-point restraints with force-limiting shoulder belts and frontal airbags for the driver and right front passenger. This was the first time that all vehicle manufacturers had to certify that their cars would meet the 50th percentile, adult male protection requirements in the 48 km/h frontal, rigid-barrier test specified in FMVSS 208. To assess the effectiveness of these certified 3-point restraint systems, a search was done of the 1988-2005 NASS data for 3-point belted, front outboard-seated, adult occupants in passenger vehicles that were equipped with airbags and that were involved in frontal, towaway collisions.
Technical Paper

SID-IIs Beta+-Prototype Dummy Biomechanical Responses

This paper presents the results of biomechanical testing of the SID-IIs beta+-prototype dummy by the Occupant Safety Research Partnership. The purpose of this testing was to evaluate the dummy against its previously established biomechanical response corridors for its critical body regions. The response corridors were scaled from the 50th percentile adult male corridors defined in International Standards Organization Technical Report 9790 to corridors for a 5th percentile adult female, using established International Standards Organization procedures. Tests were performed for the head, neck, shoulder, thorax, abdomen and pelvis regions of the dummy. Testing included drop tests, pendulum impacts and sled tests. The biofidelity of the SID-IIs beta+-prototype was calculated using a weighted biomechanical test response procedure developed by the International Standards Organization.
Technical Paper

Guidelines for Assessing the Biofidelity of Side Impact Dummies of Various Sizes and Ages

The Human Mechanical Simulation Subcommittee of the Human Biomechanics and Simulation Standards Committee of the Society of Automotive Engineers took on the task of defining test procedures and associated response guidelines to be used to assess the level of biofidelity of side impact dummies that are being developed. This paper describes the results of their efforts. Guidelines are provided for assessing the levels of biofidelity of dummies that represent 6-, 12-, and 18-month-old infants, 3-, 6-, and 10-year-old children, and of dummies that represent a small female, midsize male and large male adults. These guidelines were developed by normalizing the side impact biofidelity guidelines that were established by the International Standards Organization for the head, neck, shoulder, thorax, abdomen and pelvis of the midsize adult male.
Technical Paper

ES-2 Dummy Biomechanical Responses

This technical paper presents the results of biomechanical testing conducted on the ES-2 dummy by the Occupant Safety Research Partnership and Transport Canada. The ES-2 is a production dummy, based on the EuroSID-1 dummy, that was modified to further improve testing capabilities as recommended by users of the EuroSID-1 dummy. Biomechanical response data were obtained by completing a series of drop, pendulum, and sled tests that are outlined in the International Organization of Standardization Technical Report 9790 that describes biofidelity requirements for the midsize adult male side impact dummy. A few of the biofidelity tests were conducted on both sides of the dummy to evaluate the symmetry of its responses. Full vehicle crash tests were conducted to verify if the changes in the EuroSID-1, resulting in the ES-2 design, did improve the dummy's testing capability. In addition to the biofidelity testing, the ES-2 dummy repeatability, reproducibility and durability are discussed.
Technical Paper

Age-Specific Injury Risk Curves for Distributed, Anterior Thoracic Loading of Various Sizes of Adults Based on Sternal Deflections

Injury Risk Curves are developed from cadaver data for sternal deflections produced by anterior, distributed chest loads for a 25, 45, 55, 65 and 75 year-old Small Female, Mid-Size Male and Large Male based on the variations of bone strengths with age. These curves show that the risk of AIS ≥ 3 thoracic injury increases with the age of the person. This observation is consistent with NASS data of frontal accidents which shows that older unbelted drivers have a higher risk of AIS ≥ 3 chest injury than younger drivers.
Technical Paper

Comparison of the EUROSID and SID Impact Responses to the Response Corridors of the International Standards Organization

Side impact tests were conducted on the EUROSID and SID to assess their biofidelity compared to the response requirements of the international Standards Organization. The body regions evaluated were the head, neck, thorax, shoulder, abdomen, and pelvis. Test conditions and data normalization procedures are outlined in the report. Data plots are given which compare the impact response of each dummy to the ISO requirements. The EUROSID gave humanlike responses for most tests involving padded surface impacts, but its responses were not humanlike for rigid surface impacts. Overall, the EUROSID responses were more humanlike than the responses of the SID.
Technical Paper

The Position of the United States Delegation to the ISO Working Group 6 on the Use of HIC in the Automotive Environment

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.
Technical Paper

Small Car Air Cushion Performance Considerations

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.
Technical Paper

Hybrid III Sternal Deflection Associated with Thoracic Injury Severities of Occupants Restrained with Force-Limiting Shoulder Belts

A relationship between the risk of significant thoracic injury (AIS ≥ 3) and Hybrid III dummy sternal deflection for shoulder belt loading is developed. This relationship is based on an analysis of the Association Peugeot-Renault accident data of 386 occupants who were restrained by three-point belt systems that used a shoulder belt with a force-limiting element. For 342 of these occupants, the magnitude of the shoulder belt force could be estimated with various degrees of certainty from the amount of force-limiting band ripping. Hyge sled tests were conducted with a Hybrid III dummy to reproduce the various degrees of band tearing. The resulting Hybrid III sternal deflections were correlated to the frequencies of AIS ≥ 3 thoracic injury observed for similar band tearing in the field accident data. This analysis indicates that for shoulder belt loading a Hybrid III sternal deflection of 50 mm corresponds to a 40 to 50% risk of an AIS ≥ 3 thoracic injury.
Technical Paper

Restraint Performance of the 1973-76 GM Air Cushion Restraint System

Case reviews are given of deployment accidents of the GM 1973-76 air cushion restraint system where the occupant injury was AIS 3 or greater. Many of these injuries occurred in frontal accidents of minor to moderate collision severity where there was no intrusion or distortion of the occupant compartment. Dummy and animal test results are noted that indicate that these types of injuries could have occurred if the occupant was near the air cushion module at the time of cushion deployment. An analysis is given that indicates that for frontal accidents a restraint effectiveness of 50 percent in mitigating AIS 3 or greater injuries might be achieved if an air cushion system can be designed which would not seriously injure out-of-position occupants while still providing restraint for normally seated occupants.
Technical Paper

Thoracic Tolerance to Whole-Body Deceleration

A professional high diver, instrumented with accelerometers, performed sixteen dives from heights between 27-57 ft. For each dive, he executed a 3/4 turn and landed supine on a 3-ft deep mattress which consisted of pieces of low-density urethane foam encased in a nylon cover. Using FM telemetry, sagittal plane decelerations were recorded for a point either on the sternum or the forehead. Impact velocities and corresponding stopping distances for the thorax and the head were calculated from high-speed movies of the dives. For a 57-ft dive, the impact velocity of the thorax was 41 mph with a corresponding stopping distance of 34.6 in. The peak resultant deceleration of the thorax was 49.2 g with a pulse duration of 100 ms. The maximum rate of change of the deceleration of the thorax was 5900 g/s. No discomfort was experienced as a result of this impact. The maximum forehead deceleration occurred during a 47.0-ft drop and exceeded 56 g with a Gadd Severity Index greater than 465.
Technical Paper

The Highway Safety Research Institute Dummy Compared with General Motors Biofidelity Recommendations and the Hybrid II Dummy

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.
Technical Paper

Thoracic Injury Assessment of Belt Restraint Systems Based on Hybrid III Chest Compression

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.
Technical Paper

Brain Injury Risk Assessment of Frontal Crash Test Results

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.
Technical Paper

The Effect of Limiting Shoulder Belt Load with Air Bag Restraint

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.
Technical Paper

Pediatric Head Contours and Inertial Properties for ATD Design

Child head trauma in the United States is responsible for 30% of all childhood injury deaths with costs estimated at $10 billion per year. The common tools for studying this problem are the child anthropomorphic test devices (ATDs). The headform sizes and structural properties of child ATDs are based on various anthropometric studies and scaled Hybrid III mass and center of gravity (CG) properties. The goals of this study were to produce pediatric head and skull contours, provide estimates of pediatric head mass, mass moment of inertia and CG locations, and compare the head contours with the current child ATD head designs. To that end, computer tomography (CT) scans from one hundred eighty-five children in twelve age groups were analyzed to develop three-dimensional head and skull contours. The contours were averaged to estimate head and skull contours for children aged 1 month to 10 years. Inertial properties were estimated from a small sample of post-mortem human subjects (PMHSs).
Technical Paper

Forces on the Human Body in Simulated Crashes

Details of a new crash simulator and preliminary results from a series of cadaver knee impact experiments were presented at the Eighth Stapp Conference. During the past year additional data concerning injury to the knee-thigh-hip complex have been obtained, and the studies have been extended to consider impact to the chest. Results to date indicate that for knee impacts against a moderately padded surface it is not possible to predict whether failure of the patella, femur or pelvis will occur first, although in these studies femoral fractures occurred most frequently. A force of 1400 lb. is recommended at this time as a reasonably conservative value for the over-all injury threshold level. Volunteers tolerated impact loads to the knee of 800-1000 lb. For loads applied over the sternum through a 25-30 padded surface, static and dynamic thoracic stiffness characteristics were determined for a limited number of cadavers.
Technical Paper

Rationale for and Dimensions of Impact Surfaces for Biofidelity Tests of Different Sizes of Frontal and Side Impact Dummies

The biofidelity impact response corridors that were used to develop the Hybrid III family of dummies were established by scaling the various biofidelity corridors that were defined for the Hybrid III mid-size, adult male dummy. Scaling ratios for the responses of force, moment, acceleration, velocity, deflection, angle, stiffness and time were developed using dimensions and masses that were prescribed for the dummies. In addition, an elastic modulus ratio for bone was used to account for the differences between child and adult bone elastic properties. A similar method is being used by ISO/TC22/SC12/WG 5 to develop biofidelity guidelines for a family of side impact dummies based on scaling the biofidelity impact response corridors that are prescribed for WorldSID, a mid-size, adult male dummy.
Technical Paper

Injury Risk Curves for Children and Adults in Frontal and Rear Collisions

This paper describes the development of injury risk curves for measurements made with the CRABI and Hybrid III family of biofidelic child and adult dummies that are used to evaluate restraint systems in frontal and rear-end collision simulations. Injury tolerance data are normalized for size and strength considerations. These data are analyzed to give normalized injury risk curves for neck tension, neck extension moment, combined neck tension and extension moment, sternal compression, the rate of sternal compression, and the rate of abdominal compression for children and adults. Using these injury risk curves dummy response limits can be defined for prescribed injury risk levels. The injury risk levels associated with the various injury assessment reference values currently used with the CRABI and Hybrid III family of dummies are noted.