WorldSID Prototype Dummy Biomechanical Responses

Kinematic and Biomechanical Response of Post-Mortem Human Subjects Under Various Pre-Impact Postures to High-Rate Vertical Loading Conditions

Limited data exist on the injury tolerance and biomechanical response of humans to high-rate, under-body blast (UBB) loading conditions that are commonly seen in current military operations, and there are no data examining the influence of occupant posture on response. Additionally, no anthropomorphic test device (ATD) currently exists that can properly assess the response of humans to high-rate UBB loading. Therefore, the purpose of this research was to examine the response of post-mortem human surrogates (PMHS) in various seated postures to high-rate, vertical loading representative of those conditions seen in theater. In total, six PMHS tests were conducted using loading pulses applied directly to the pelvis and feet of the PMHS: three in an acute posture (foot, knee, and pelvis angles of 75°, 75°, and 36°, respectively), and three in an obtuse posture (15° reclined torso, and foot, knee, and pelvis angles of 105°, 105°, and 49.5°, respectively). Tests were conducted with a seat velocity pulse that peaked at ~4 m/s with a 30-40 ms time to peak velocity (TTP) and a floor velocity that peaked at 6.9-8.0 m/s (2-2.75 ms TTP). Posture condition had no influence on skeletal injuries sustained, but did result in altered leg kinematics, with leg entrapment under the seat occurring in the acute posture, and significant forward leg rotations occurring in the obtuse posture. These data will be used to validate a prototype ATD meant for use in high-rate UBB loading scenarios.

Lower Cervical Spine Motion Segment Computational Model Validation: Kinematic and Kinetic Response for Quasi-Static and Dynamic Loading

Advanced computational human body models (HBM) enabling enhanced safety require verification and validation at different levels or scales. Specifically, the motion segments, which are the building blocks of a detailed neck model, must be validated with representative experimental data to have confidence in segment and, ultimately, full neck model response. In this study, we introduce detailed finite element motion segment models and assess the models for quasi-static and dynamic loading scenarios. Finite element segment models at all levels in the lower human cervical spine were developed from scans of a 26-yr old male subject. Material properties were derived from the in vitro experimental data. The segment models were simulated in quasi-static loading in flexion, extension, lateral bending and axial rotation, and at dynamic rates in flexion and extension in comparison to previous experimental studies and new dynamic experimental data introduced in this study. Single-valued experimental data did not provide adequate information to assess the model biofidelity, while application of traditional corridor methods highlighted that data sets with higher variability could lead to an incorrect conclusion of improved model biofidelity. Data sets with continuous or multiple moment–rotation measurements enabled the use of cross-correlation for an objective assessment of the model and highlighted the importance of assessing all motion segments of the lower cervical spine to evaluate the model biofidelity. The presented new segment models of the lower cervical spine, assessed for range of motion and dynamic/traumatic loading scenarios, provide a foundation to construct a biofidelic model of the spine and neck, which can be used to understand and mitigate injury for improved human safety in the future.

Region-specific deflection responses of WorldSID and ES2-re devices in pure lateral and oblique side impacts

The objective of this study was to determine region-specific deflection responses of the WorldSID and ES2 -re devices under pure lateral and oblique side impact loading. A modular, anthropometry-specific load wall was used. It consisted of the Shoulder, Thorax, Abdomen, superior Pelvis, and inferior Pelvis plates, termed the STAPP load wall design. The two devices were positioned upright on the platform of a bench seat, and sled tests were conducted at 3.4, 6.7, and 7.5 m/s. Two chestbands were used on each dummy at the thoracic and abdominal regions. Internal sensors were also used. Effective peak deflections were obtained from the chestband contours. Based on the preselected lateral-most point/location on the pretest contour, "internal sensor-type" peak deflections were also obtained using chestband contours. In addition, peak deflection data were obtained from internal sensor records. In oblique tests, the mean "IR-TRACC-type" peak deflections in the WorldSID device were 40 to 80% of effective peak deflections, whereas the mean "potentiometer-type" peak deflections in the ES2-device were 7 to 50%. The WorldSID device appears to better mimic region -specific responses to oblique loading than the ES2-re device, likely due to the differences in its des ign of the thoracic and abdominal regions. While the lateral -most point corresponding to the current 1D IR-TRACC location was found to replicate the pure lateral response, it was found to be less than optimal to track oblique loading. Although a laterally positioned sensor provides lower peak deflections in oblique loading, the addition of an angle-measuring sensor should allow modulating the translational metric for this mode. From this perspective, it may be worthwhile to use a 2D IR-TRACC or an optical sensor to verify these findings without chestband measures. Such an analysis has the potential to modify thoracic and abdominal injury criteria to account for obliqueness.

WorldSID Dummy Head-Neck Biofidelity Response

Accident studies indicate that serious neck injuries are generally infrequent in side crashes. However, given the rapid changes in side impact protection technology, such as side airbags and curtain systems, the nature of head-neck interactions is likely to change. Consequently, the newest generation of anthropomorphic test devices for side impact should provide realistic prediction of the head-neck kinematics and include meaningful measurements related to risk of head and neck injury. The WorldSID dummy has been assessed against a set of five test conditions that have been used to define biofidelity impact response targets. Three of the five test conditions are recommended by ISO TR9790 (ISO 1997), the NBDL 7.2 G, 6.9 m/s lateral sled impact reported by Ewing et al. (1977) and Wismans et al. (1986) , the Patrick and Chou lateral, 6.7 G 5.8 m/s (1976) and Tarriere lateral 12.2 g, 6,1 m/s sled impact (ISO 1997). Due to its expected loading environment, the dummy neck performance has also been evaluated for neck bending in frontal flexion and extension (Mertz and Patrick, 1971). The 5th test condition is the NBDL 45 degrees frontal-oblique sled test (Wismans 1986, Philippens 2004). The latter and two of the ISO TR9790 test conditions form the basis of the draft IHRA requirements for evaluating side impact dummy biomechanical responses. The paper reports on the findings of the assessment of the WorldSID pre-production dummy. The Mertz and Patrick OC moment-head angle corridor is used as supplemental requirement for frontal flexion-extension. The biofidelity requirements contain both kinematic and dynamic response targets. The neck has a good performance for NBDL lateral and Tarriere requirements, and the Mertz OC moment-flexion angle. The performance for the Patrick and Chou, the NBDL oblique test conditions and the Mertz OC moment extension angle are fair to marginal. The repeatability performance of the dummy was found to be good for all lateral and most oblique test parameters. The neck design does not allow much more further optimization without fundamental changes.

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. Finally, this technical paper will compare the biofidelity ratings of the current adult side impact dummies with the ES-2 dummy, which received an overall dummy biofidelity rating of 4.6.