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This work describes the development of a three-dimensional finite element model of the human ankle/foot complex. This model depicts the primary elements of a 50th percentile human ankle. It includes all the bones of the foot up to the distal tibia/fibula. It also contains the soft tissues of the plantar surface of the foot along with most of the ankle joint ligaments and retinacula. To calibrate the model, a plate with various initial velocities of 5, 7.5 and 10 mph is impacted at the plantar surface of the foot. The model is strictly stabilized by the intrinsic anatomical geometry and the ligamentous structure. It demonstrates to a great extent its capacity to replicate the dynamic response. Global responses of output acceleration and force time histories are obtained and compared reasonably well with experimental data.

A finite element model of the human thorax was merged with a rigid body finite element implementation of the Hybrid III dummy (after removal of the Hybrid III thorax) and the combined model is used in simulations of an out of position driver during airbag deployment. Parameters related to injury, such as A-P thorax deformation, Viscous Criterion, rib stress distribution and strain in the thoracic contents are used to quantify the thoracic injury response. Initial driver position is varied to examine the relationship between distance from the airbag module and thoracic injury risk. The potential for injury mitigation through modulation of airbag inflation after initiation is also investigated. The utility of the combined model as an effective tool for the analysis of occupant kinematics and dynamics, examination of injury mechanisms, and optimization of restraint system design parameters is demonstrated.

Accident cases are examined to determine the injury mechanism for foot/ankle moderate and greater injuries in vehicle crashes. The authors examine 480 in-depth cases from the National Accident Sampling System for the years 1979 through 1987. An injury mechanism - a description of how the foot/ankle physically interacted with the interior of the vehicle - is assigned to each of the injured occupants. For the accidents in which the 480 occupants were injured, the more prominent types of vehicle collisions are characterized.

Computational simulations are conducted for several head impact scenarios using a three dimensional finite element model of the human brain in conjunction with accelerometer data taken from crash test data. Accelerometer data from a 3-2-2-2 nine accelerometer array, located in the test dummy headpart, is processed to extract both rotational and translational velocity components at the headpart center of gravity with respect to inertial coordinates. The resulting generalized six degree-of-freedom description of headpart kinematics includes effects of all head impacts with the interior structure, and is used to characterize the momentum field and inertial loads which would be experienced by soft brain tissue under impact conditions. These kinematic descriptions are then applied to a finite element model of the brain to replicate dynamic loading for actual crash test conditions, and responses pertinent to brain injury are analyzed.

This paper is part of a four year study to systematically define side impact injury in terms of the kinetic response of a suitable anthropomorphic dummy. Last year a paper was presented at the Experimental Safety Vehicle Conference in Germany which analyzed side impact dummy response and injury prediction based on cadaver data generated by the Highway Safety Research Institute. These subjects were generally older than those discussed in the current paper. This paper includes data from a number of University of Heidelberg cadaver sled tests-including padding tests which we recently found to be (1) critical for a definitive analysis and (2) previously not available. Two advanced dummies, whose design specifications are based upon biomechanical data, are currently being evaluated by the biomechanical community. The two dummies are (1) a Side Impact Dummy (SID) designed by the Highway Safety Research Institute (HSRI) and (2) the Association Peugeot-Renault (APR) dummy from France.

Since 1976, the National Highway Traffic Safety Administration (NHTSA) has pursued biomechanical research concerning lateral impacts to automotive occupants. These efforts have included (a) the generation of an experimental data base containing both detailed engineering and physiological responses of human surrogates experiencing lateral impacts, (b) the analysis of this data base to develop both an injury index linking the engineering parameters to an injury severity level and response corridors to guide in the design of a test dummy, and (c) the development and refinement of a side impact test dummy suitable for use in safety systems development and evaluation. The progress of these efforts has been periodically reported in the literature [1-17]* and these references document the evolutionary trail NHTSA has followed over the duration of this research program.

Forty-two side impact cadaver sled tests were conducted at 24 and 32 km/h impact speeds into rigid and padded walls. The post-mortem human subjects were instrumented with accelerometers on the ribs and spine and chest bands around the thorax and abdomen to characterize their mechanical response during the impact. Load cells at the wall measured the impact force at the level of the thorax, abdomen, pelvis, and lower extremities. The resulting injuries were determined through detailed autopsy and radiography. Rib fractures with or without associated hemo/pneumo thorax or flail chest were the most common injury with severity ranging from AIS=0 to 5. Full and half thorax deflections were computed from the chest band data. The cadaver test data was analyzed using ANOVA and logistic regression. The age of the subject at the time of death had influence on injury outcome while gender and mass of the subject had little or no influence on injury outcome.

A new biofidelity assessment system is being developed and applied to three side impact dummies: the WorldSID-α, the ES-2 and the SID-HIII. This system quantifies (1) the ability of a dummy to load a vehicle as a cadaver does, “External Biofidelity,” and (2) the ability of a dummy to replicate those cadaver responses that best predict injury potential, “Internal Biofidelity.” The ranking system uses cadaver and dummy responses from head drop tests, thorax and shoulder pendulum tests, and whole body sled tests. Each test condition is assigned a weight factor based on the number of human subjects tested to form the biomechanical response corridor and how well the biofidelity tests represent FMVSS 214, side NCAP (SNCAP) and FMVSS 201 Pole crash environments.

Analysis of experimental acceleration time history data obtained from a thoracic instrumentation array has been performed. The data were generated under test conditions which include realistic frontal impacts in belt, air bag, and steering column systems and side impacts with rigid and padded door structures. Data from frontal and lateral pendulum impacts were also included. The results demonstrate that the instrumentation array captures sufficient information from the impact event to allow prediction of resulting thoracic trauma, defined either as thoracic AIS or total number of thoracic fractures, using a single function for each injury measure. Each function is universal in the sense that it is valid for all test modes and directions of impact. A strategy for developing a surrogate thorax to implement this injury predictive methodology is discussed and preliminary specifications are presented.

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.

In an effort to better understand thoracic trauma in frontal impacts, seventy-one frontal impact sled tests were conducted using post-mortem human subjects in the driver's position. Various contemporary automotive restraint systems were used in these tests. The post-mortem subjects were instrumented with accelerometers and chest bands to characterize their mechanical response during the impact. The resulting injury from the impact was determined through radiography and detailed autopsy and its severity was coded according to the Abbreviated Injury Scale. The measured mechanical responses were analyzed using statistical procedures. In particular, linear logistic regression was used to develop models which associate the measured mechanical parameters to the observed thoracic injury response. Univariate and multivariate models were developed taking into consideration potential confounders and effect modifiers.

A series of seventy-two pendulum-type impact tests were performed on six NHTSA Side Impact Dummies (SID) to assess dummy repeatability and reproducibility. A quantity called the Normalized Integral Square Error (NISE) is used to quantify the difference between acceleration responses from repeat tests. Limits for the NISE are developed to define acceptable differences in terms of phase shift, amplitude, and shape. Results indicate that the SID is repeatable in all of the test cases considered and fairly reproducible in 90° lateral impacts although this is not shown conclusively. Before the testing could be performed it was necessary to correct several durability problems with the SID that were identified while early production versions of the dummy were being tested. These modifications are described briefly.

Axial loading of the calcaneus-talus-tibia complex is an important injury mechanism for moderate and severe vehicular foot-ankle trauma. To develop a more definitive and quantitative relationship between biomechanical parameters such as specimen age, axial force, and injury, dynamic axial impact tests to isolated lower legs were conducted at the Medical College of Wisconsin (MCW). Twenty-six intact adult lower legs excised from unembalmed human cadavers were tested under dynamic loading using a mini-sled pendulum device. The specimens were prepared, pretest radiographs were taken, and input impact and output forces together with the pathology were obtained using load cell data. Input impact forces always exceeded the forces recorded at the distal end of the preparation. The fracture forces ranged from 4.3 to 11.4 kN.

A series of 24 pregnant baboons was impacted under similar conditions. The only major variable was the difference in maternal restraint. The fetal death rate of 8.3% (1/12) among maternal animals impacted with three-point restraint was significantly different from five fetal deaths among 10 maternal animals impacted under lap belt restraint alone (p < 0.05). It is concluded that shoulder harness restraint should be recommended for use by pregnant travelers as being significantly more protective of fetal welfare when compared with lap belt restraint alone.

An ordinary rigid bumper system and a compliant bumper system for pedestrian protection developed by the NHTSA, US Department of Transportation, were compared in an experimental study of leg injuries in car-pedestrian accidents. Human leg specimens were struck in 20 experiments with a production car front using the two bumper types. Impacts were made with an ordinary front configuration with the bumpers at the 45 cm level and a 12.5 cm lower front configuration with the bumpers at the 32.5 cm level. The impact velocity was 30-32 km/h. Serious leg injuries were noted with both front configurations and bumper types. The compliant bumper seemed to cause less serious injuries than the rigid one, and the lower front configuration seemed to cause less serious injuries than the ordinary one. A lower bumper level than today's standard and a compliant bumper type is recommended in combination to reduce the risk of serious leg injuries in car-pedestrian accidents.

Lateral impacts have been shown to produce a large portion of both serious and fatal injuries within the total automotive crash problem. These injuries are produced as a result of the rapid changes in velocity that an automobile occupant's body experiences during a crash. In an effort to understand the mechanisms of these injuries, an experimental program using human surrogates (cadavers) was initiated. Initial impact velocity and compliance of the lateral impacting surface were the primary test features that were controlled, while age of the test specimen was varied to assess its influence on the injury outcome. Instrumentation consisted of 24 accelerometer channels on the subjects along with contact forces measured on the wall both at the thoracic and pelvic level. The individual responses and resulting injuries sustained by 11 new subjects tested at the University of Heidelberg are presented in detail.

The purpose of this study was to investigate the use of the chestband in side impact conditions by conducting validation experiments, and evaluating its feasibility by conducting a series of human cadaver tests under side impact crash scenarios. The chestband validation tests were conducted by wrapping the device around the thorax section of the Side Impact Dummy at its uppermost portion. The anthropomorphic test device was seated on a Teflon pad on a platform to accept impact from the side via a pendulum system. Tests were conducted at 4.5, 5.7, and 6.7 m/sec velocities using round and flat impactors. Retroreflective targets were placed at each strain gauge channel on the edge of the chestband. The test was documented using a high-speed digital video camera operating at 4500 frames/sec. Deformation contours and histories were obtained using the chestband electronic signals in combination with the RBAND-PC software.

Nineteen sled impact tests were conducted simulating a frontal collision exposure for an unrestrained driver. The deceleration sled buck configuration utilized the passenger compartment of a late model compact passenger vehicle, a rigid driver's seat, and a custom fabricated energy-absorbing steering column and wheel assembly. Sled impact velocities ranged from 24.1 to 42.6 km/hr. The purpose of the study was to investigate the kinematic and kinetic interaction of the driver and the energy-absorbing steering assembly and their relationship to the thoracic/abdominal injuries produced. The similarities and differences between human cadaver and anthropomorphic dummy subjects were quantified.

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.

This study was conducted to collect data and gain insights relative to the mechanisms and factors involved in hip injuries during frontal crashes and to study the tolerance of hip injuries from this type of loading. Unembalmed human cadavers were seated on a standard automotive seat (reinforced) and subjected to knee impact test to each lower extremity. Varying combinations of flexion and adduction/abduction were used for initial alignment conditions and pre-positioning. Accelerometers were fixed to the iliac wings and twelfth thoracic vertebral spinous process. A 23.4-kg padded pendulum impacted the knee at velocities ranging from 4.3 to 7.6 m/s. The impacting direction was along the anteroposterior axis, i.e., the global X-axis, in the body-fixed coordinate system. A load cell on the front of the pendulum recorded the impact force. Peak impact forces ranged from 2,450 to 10,950 N. The rate of loading ranged from 123 to 7,664 N/msec. The impulse values ranged from 12.4 to 31.9 Nsec.