Stapp car crash journal最新文献

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.

Analysis and validation of current scaling relationships and existing response corridors using animal surrogate test data is valuable, and may lead to the development of new or improved scaling relationships. For this reason, lateral pendulum impact testing of appropriate size cadaveric porcine surrogates of human 3-year-old, 6-year-old, 10-year-old, and 50^th percentile male age equivalence, were performed at the thorax and abdomen body regions to compare swine test data to already established human lateral impact response corridors scaled from the 50^th percentile human adult male to the pediatric level to establish viability of current scaling laws. Appropriate Porcine Surrogate Equivalents PSE for the human 3-year-old, 6-year-old, 10-year-old, and 50^th percentile male, based on whole body mass, were established. A series of lateral impact thorax and abdomen pendulum testing was performed based on previously established scaled lateral impact assessment test protocols. The PSE thorax and abdominal impact response data were assessed against previously established scaled human thorax lateral impact response corridors and scaled abdominal oblique impact response corridors for the 3-year-old, 6-year-old, 10-year-old, and 50^th percentile human male based on lateral pendulum impact testing. The overall findings of the current study confirm that lateral impact force response of the thorax and abdomen of appropriate weight porcine surrogates established for human-equivalent-age 3-year-old, 6-year-old, 10-year-old, and 50^th adult male are consistent with the previously established human scaled lateral impact response corridors). Porcine surrogate biomechanics testing can prove to be a powerful research means to further characterize and understand injury and response in lateral impact.

A total of 20 full-scale frontal sled tests were conducted using the Hybrid III (HIII), THOR-M and post-mortem human surrogates (PMHSs) to evaluate the thoracic biofidelity of the HIII and THOR-M under various belted restraint conditions. Each surrogate was tested under three belted restraint conditions: knee bolster, knee bolster and steering wheel airbag, and knee bolster airbag and steering wheel airbag. In order to assess the relative biofidelity of each ATD, external thoracic deflections were quantitatively compared between the ATDs and PMHSs using an objective rating metric. The HIII had slightly higher biofidelity than the THOR-M for the external thoracic deflections. Specifically, the THOR-M lower chest was more compliant compared to the other surrogates. However, the THOR-M exhibited expansion of the lower chest opposite belt loading, which was also observed to some degree in the PMHSs. The efficacy of the current injury risk prediction instrumentation and criteria were also evaluated for each surrogate. The THOR-M and its proposed injury risk criteria predicted the injuries observed in the PMHS tests better than the HIII. The PMHS injury criteria over-predicted the amount of chest deflection necessary to produce a severe injury and, consequently, under-predicted injury risk. The results of this study indicate that further testing should be performed to evaluate the biofidelity of the THOR-M thorax under more conditions. Furthermore, current thoracic injury risk criteria, which were developed using censored data, may not be effective at predicting injuries for all restraints and experimental conditions.

The study firstly aimed at looking whether sacroilium (SI) fractures could be sustained as unique pelvic injuries in side impact real world automotive accidents. Secondarily, the sacroilium fractures observed in conjunction with other pelvic fractures were analyzed to investigate the existence of injury association patterns. Two real world accident databases were searched for SI fractures. The occupants selected were front car passengers older than 16, involved in side, oblique or frontal impact, with AIS2+ pelvic injuries. In frontal impact, only the belted occupants were selected. The cases were sorted by the principal direction of force (dof) and the type of pelvic injury, namely SI, pubic rami, iliac wing, acetabulum, pubic symphysis, and sacrum injuries. The relation between SI and pubic rami injuries were investigated first. The first database is an accident database composed of cases collected in France by car manufacturers over a period of approximately 40 years. In total it contains approximately 28 000 occupants involved in all types of accident configurations. The occupant injuries, as well as the vehicle deformations, are described in detail. The second database gathered accident cases from 7 zones monitored in Great Britain over a period ranging from 1998 to 2005. All the cases collected include at least one towed away vehicle with at least one injured occupant. In total the database contains approximately 15 000 occupants. The occupant injuries are described in details and autopsy reports were screened when available. Results - In the French database, 39 occupants sustained SI fractures. Out of 39 SI fractures, 32 were associated with pubic rami fractures and 5 additional were associated with other pelvis ring fractures. In the UK database, 46 occupants sustained SI fractures. Out of 46 SI fractures, 34 were associated with pubic rami fractures and 8 additional were associated with other pelvis ring fractures. In side impact (dof 2, 3, 4, 8, 9 or 10 o'clock), in the cases where the side is known for both the SI fractures and pelvic ring injuries, both injuries were on the same side in 70% of the cases. Overall, out of 85 SI fractures cases, only one was clearly identified as occurring with no other pelvic injury and 3 with pelvic injuries other than pelvic ring injury. Conclusions - Overall, from the real world automotive accidents selected at any dof, SI fractures were observed to be associated with other pelvic ring fractures in 96% of the cases. On the reverse, in side impact (dof 2, 3, 4, 8, 9 or 10 o'clock in the LAB database), 89% of the pubic rami fractures occurred without any SI fractures. From a mechanical standing point, it suggests that the SI fractures is a structure more resistant than the rest of the pelvic ring. Overall, 70% of SI fractures were observed in various types of side impacts and 30% in frontal impacts.

Computational models of anthropomorphic test devices (ATDs) can be used in crash simulations to quantify the injury risks to occupants in both a cost-effective and time-sensitive manner. The purpose of this study was to validate the performance of a 50^th percentile THOR finite element (FE) model against a physical THOR ATD in 11 unique loading scenarios. Physical tests used for validation were performed on a Horizontal Impact Accelerator (HIA) where the peak sled acceleration ranged from 8-20 G and the time to peak acceleration ranged from 40-110 ms. The directions of sled acceleration relative to the THOR model consisted of -GX (frontal impact), +GY (left-sided lateral impact), and +GZ (downward vertical impact) orientations. Simulation responses were compared to physical tests using the CORrelation and Analysis (CORA) method. Using a weighted method, the average response and standard error by direction was +GY (0.83±0.03), -GX (0.80±0.01), and +GZ (0.76±0.03). Qualitative and quantitative results demonstrated the FE model's kinetics and kinematics were sufficiently validated against its counterpart physical model in the tested loading directions.

Accident emergency calling systems (AECSs) are signaled by the deployment of airbags, which causes them to automatically emit information providing the location of the accident site to a public service answering party (PSAP). In some realworld accidents, airbags have failed to deploy. This study clarifies the factors that influence the nondeployment of front airbags in vehicle-vehicle collisions, investigating nondeployment of the driver-side front airbags in sedans and light passenger cars (LPCs) from Japanese accident data. The component rates of deployment for front airbags tend to be higher than those of nondeployment at higher values of pseudo-ΔV in vehicle-vehicle frontal impacts. For both sedans and LPCs, the transition zones between nondeployment and deployment of the front airbag occur at pseudo-ΔV values of 30-50 km/h (ΔV ≈ 21-35 km/h). For mutual impact locations where sedans and LPCs impact opponent vehicles at pseudo-ΔV ≥ 40 km/h (ΔV ≈ 28 km/h) in frontal impacts, the component rate of front airbag nondeployment is higher than that of deployment in right-to-right impacts. The results indicate that factors influencing front airbag nondeployment in vehicle-vehicle collisions are ΔV, impact offset configuration, and crossing angle. Considering front airbag nondeployment in real-world accidents, AECSs should have other functions, such as a manual button, to emit information in addition to automatic emission via airbag signaling.

During Operation Iraqi Freedom and Operation Enduring Freedom, improvised explosive devices were used strategically and with increasing frequency. To effectively design countermeasures for this environment, the Department of Defense identified the need for an under-body blast-specific Warrior Injury Assessment Manikin (WIAMan). To help with this design, information on Warfighter injuries in mounted under-body blast attacks was obtained from the Joint Trauma Analysis and Prevention of Injury in Combat program through their Request for Information interface. The events selected were evaluated by Department of the Army personnel to confirm they were representative of the loading environment expected for the WIAMan. A military case review was conducted for all AIS 2+ fractures with supporting radiology. In Warfighters whose injuries were reviewed, 79% had a foot, ankle or leg AIS 2+ fracture. Distal tibia, distal fibula, and calcaneus fractures were the most prevalent. The most common injury mechanisms were bending with probable vehicle contact (leg) and compression (foot). The most severe injuries sustained by Warfighters were to the pelvis, lumbar spine, and thoracic spine. These injuries were attributed to a compressive load from the seat pan that directly loaded the pelvis or created flexion in the lumbar spine. Rare types of injuries included severe abdominal organ injury, severe brain injury, and cervical spine injury. These typically occurred in conjunction with other fractures. Mitigating the frequently observed skeletal injuries using the WIAMan would have substantial long-term benefits for Warfighters.

Chest injuries occur frequently in frontal collisions. During impact, tension in the lap belt is transferred to the inboard shoulder belt, which compresses the lower ribs of the occupant. In this research, inboard shoulder belt and lap belt geometries and forces were investigated to reduce chest deflection. First, the inboard shoulder belt geometry was changed by the lap/shoulder belt (L/S) junction for the rear seat occupant in sled tests using Hybrid III finite element simulation, sled tests and THOR simulation. As the L/S junction was closer to the ASIS (anterior superior iliac spine), chest deflection of the Hybrid III was smaller. The L/S junction around the ilium has the potential to reduce chest deflection without significant increase of head excursion. For THOR, although the chest deflection reduction effect due to closer L/S junction to the ASIS was observed, chest deflection was still substantially large since the lap belt overrode the ASIS. Second, measures to hook the ASIS of the THOR by the lap belt were examined. Sled tests at 30 and 50 km/h were conducted with THOR in the rear seat, and it was demonstrated that the outboard lap belt and buckle pretensioners improved the lap belt and ASIS interaction, and were also useful in reducing the deflection at the inboard-side of the lower chest. Finally, the lap belt overlap with the ASIS was compared among 10 volunteers, Hybrid III, and THOR. Some volunteers had the ASIS located at the torso-thigh junction, and the lap belt did not overlap the ASIS sufficiently. However, although the ASIS location of THOR is also at the torso-thigh junction, the lap belt overlapped the ASIS because of the abdomen's and femur's shape. In the future, it will be necessary to consider that the outboard lap belt and buckle pretensioners are also effective for the ASIS restraint of all human car occupants.

In the last decade, extensive efforts have been made to understand the physics of submarining and its consequences in terms of abdominal injuries. For that purpose, 27 Post Mortem Human Subject (PMHS) tests were performed in well controlled conditions on a sled and response corridors were provided to assess the biofidelity of dummies or human body models. All these efforts were based on the 50th percentile male. In parallel, efforts were initiated to transfer the understanding of submarining and the prediction criteria to the THOR dummies. Both the biofidelity targets and the criteria were scaled down from the 50th percentile male to the 5th percentile THOR female. The objective of this project was to run a set of reference PMHS tests in order to check the biofidelity of the THOR F05 in terms of submarining. Three series of tests were performed on nine PMHS, the first one was designed to avoid submarining, the second and third ones were designed to result in submarining. In the first configuration, no submarining was observed in 3 cases out of 4 and only one iliac wing fracture occurred in one subject. In the second and third configurations, all subjects but one sustained submarining. In addition, two subjects out of three in the third configuration sustained substantial iliac wing fractures. Nevertheless, all configurations can be represented by at least one or several cases without any pelvis fracture. Corridors were constructed for the external forces and the PMHS kinematics. They are provided in this paper as new experimental references to assess the biofidelity of small female human surrogates in different configurations where submarining did or did not occur.

Cervical spine injuries can occur in military scenarios from events such as underbody blast events. Such scenarios impart inferior-to-superior loads to the spine. The objective of this study is to develop human injury risk curves (IRCs) under this loading mode using Post Mortem Human Surrogates (PMHS). Twenty-five PMHS head-neck complexes were obtained, screened for pre-existing trauma, bone densities were determined, pre-tests radiological images were taken, fixed in polymethylmethacrylate at the T2-T3 level, a load cell was attached to the distal end of the preparation, positioned end on custom vertical accelerator device based on the military-seating posture, donned with a combat helmet, and impacted at the base. Posttest images were obtained, and gross dissection was done to confirm injuries to all specimens. Axial and resultant forces at the cervico-thoracic joint was used to develop the IRCs using survival analysis. Data were censored into left, interval, and uncensored observations. The Brier score metric was used to rank the variables. The optimal metric describing the underlying response to injury was associated with the axial force, ranking slightly greater than the resultant force, both with BMD covariates. The results from the survival analysis indicated all IRCs are in the "fair" to "good" category, at all risk levels. The BMD was found to be a significant covariate that best describes the response of the helmeted head-neck specimens to injury. The present experimental protocol and IRCs can be used to conduct additional tests, matched-pair tests with the WIAMan and/or other devices to obtain injury assessment risk curves (IARCs) and injury assessment risk values (IARVs) to predict injury in crash environments, and these data can also be used for validating component-based head-neck and human body computational models.