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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.

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.

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.

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.

Side 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 an automobile occupant's body experiences during a crash. Any improvement to the side impact problem will be brought about by means which will ultimately modify the occupant's rapid body motions to such a degree that they will no longer produce injuries of serious consequence. Accurate knowledge of both the body's motion and resulting injuries under a variety of impact conditions is needed to achieve this goal. Possession of this knowledge will then permit development of accurate anthropomorphic test devices and injury criteria which can be used to create effective injury countermeasures in vehicles.

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.

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.

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.

The evaluation and mitigation of injury in the automotive crash environment is often achieved by monitoring and limiting the magnitude of forces and/or moments being applied to or transmitted through dummy structures representing particular portions of the human anatomy. Examples of body areas where this is the practice are the neck, the thoracic and lumbar spine, the pelvis, as well as the upper and lower extremities. Implicit within this process is the assumption that the observed forces are directly proportional to local failure metrics such as stress and/or strain. However, a variety of experimental efforts have demonstrated that many of these anatomical structures exhibit, to various degrees, viscoelastic behavior and time or rate dependent failure properties. This work develops a methodology that generalizes the results of various experimental observations.

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.

A number of tests conducted under the sponsorship of the FAT were reported in papers at two previous Stapp Conferences and an Experimental Safety Vehicle Conference. These tests featured human cadavers and three different Anthropomorphic Test Devices (ATD) designed for use in lateral impacts. Test subjects were placed in Opel car bodies and impacted laterally by CCMC moving deformable barriers. In the previous papers, the reported responses of the human cadavers had wide variability and none of the ATD's studied featured good biofidelity. In this effort, a reexamination of the available data was undertaken and the process and results of applying different analysis techniques to the cadaver data, which resulted in significantly reduced scatter and variability, are discussed. Comparisons of the impact responses of the cadavers and the NHTSA developed Side Impact Dummy are also made.