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Technical Paper

Reference PMHS Sled Tests to Assess Submarining of the Small Female

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.
Technical Paper

Human Shoulder Response to Lateral Impact in Intermediate Loading Conditions Between High-Velocity, Short-Duration and Low-Velocity, Long-Duration

The EuroSID-2re (ES-2re) Anthropomorphic Test Device (ATD) commonly known as the crash test dummy is also used in the military domain to assess the risk of injury of armored vehicles occupants from lateral impact. The loading conditions range from low velocity - long duration impacts (4 m/s - 50 ms) similar to the automotive domain, to high velocity - short duration impacts (28 m/s - 3 ms) corresponding to cases where the panel deforms under an explosion. The human shoulder response to lateral impact was investigated at bounds of the loading condition spectrum previously mentioned, and also at intermediate conditions (14 m/s - 9 ms) in previous studies. The aim of the current study is to provide additional insight at the intermediate loading conditions which are not found in the literature.
Technical Paper

Investigation of Pelvic Injuries on Eighteen Post Mortem Human Subjects Submitted to Oblique Lateral Impacts

The aim of this study was to investigate the sacroiliac joint injury mechanism. Two test configurations were selected from full scale car crashes conducted with the WorldSID 50th dummy resulting in high sacroiliac joint loads and low pubic symphysis force, i.e. severe conditions for the sacroiliac joint. The two test conditions were reproduced in laboratory using a 150-155 kg guided probe propelled respectively at 8 m/s and 7.5 m/s and with different shapes and orientations for the plate impacting the pelvis. Nine Post Mortem Human Subject (PMHS) were tested in each of the two configurations (eighteen PMHS in total). In order to get information on the time of fracture, eleven strain gauges were glued on the pelvic bone of each PMHS. Results - In the first configuration, five PMHS out of nine sustained AIS2+ pelvic injuries. All five presented sacroiliac joint injuries associated with pubic area injuries.
Technical Paper

A Comparison of Sacroiliac and Pubic Rami Fracture Occurrences in Oblique Side Impact Tests on Nine Post Mortem Human Subjects

The WorldSID dummy can be equipped with both a pubic and a sacroiliac joint (S-I joint) loadcell. Although a pubic force criterion and the associated injury risk curve are currently available and used in regulation (ECE95, FMVSS214), as of today injury mechanisms, injury criteria, and injury assessment reference values are not available for the sacroiliac joint itself. The aim of this study was to investigate the sacroiliac joint injury mechanism. Three configurations were identified from full-scale car crashes conducted with the WorldSID 50th percentile male where the force passing through the pubis in all three tests was approximately 1500 N while the sacroiliac Fy / Mx peak values were 4500 N / 50 Nm, 2400 N / 130 Nm, and 5300 N / 150 Nm, respectively. These tests were reproduced using a 150 kg guided probe impacting Post Mortem Human Subjects (PMHS) at 8 m/s, 5.4 m/s and 7.5 m/s.
Technical Paper

The Effect of Upper Body Mass and Initial Knee Flexion on the Injury Outcome of Post Mortem Human Subject Pedestrian Isolated Legs

In the ECE 127 Regulation on pedestrian leg protection, as well as in the Euro NCAP test protocol, a legform impactor hits the vehicle at the speed of 40 kph. In these tests, the knee is fully extended and the leg is not coupled to the upper body. However, the typical configuration of a pedestrian impact differs since the knee is flexed during most of the gait cycle and the hip joint applies an unknown force to the femur. This study aimed at investigating the influence of the inertia of the upper body (modelled using an upper body mass fixed at the proximal end of the femur) and the initial knee flexion angle on the lower limb injury outcome. In total, 18 tests were conducted on 18 legs from 9 Post Mortem Human Subjects (PMHS). The principle of these tests was to impact the leg at 40 kph using a sled equipped with 3 crushing steel tubes, the stiffness of which were representative of the front face of a European sedan (bonnet leading edge, bumper and spoiler).
Technical Paper

Comparison of the Thorax Dynamic Responses of Small Female and Midsize Male Post Mortem Human Subjects in Side and Forward Oblique Impact Tests

Despite the increasing knowledge of the thorax mechanics in impact loadings, the effects of inter-individual differences on the mechanical response are difficult to take into account. For example, the biofidelity corridors for the small female or large male are extrapolated from the midsize male corridors. The present study reports on the results of new tests performed on small female Post Mortem Human Subjects (PMHS), and compares them with test results on midsize male PMHS. Three tests in pure side impact and three tests in forward oblique impact were performed on the thorax of small female specimens. The average weight and stature were 43 kg and 1.58 m for the small female specimens. The initial speed of the impactor was 4.3 m/s. The mass and the diameter of the impactor face were respectively 23.4 kg and 130 mm. The instrumentation and methodology was the same as for the tests published in 2008 by Trosseille et al. on midsize male specimens.
Technical Paper

Kinematics and Dynamics of the Pelvis in the Process of Submarining using PMHS Sled Tests

This study focused on a better understanding and characterization of the submarining phenomenon that occurs in frontal crashes when the lap belt slides over the anterior superior iliac spine. Submarining is the consequence of the pelvis kinematics relative to the lap belt, driven by the equilibrium of forces and moments applied to the pelvis. The study had two primary purposes; the first was to provide new PMHS data in submarining test configurations, the second was to investigate the Hybrid II and Hybrid III dummies biofidelity regarding submarining. Several Post Mortem Human Subject (PMHS) studies have been published on this subject. However, the lack of information about the occupant initial positioning and the use of car seats make it difficult to reconstruct these tests. Furthermore, the two dummies are rarely compared to PMHS in submarining test configurations. A fifteen frontal sled test campaign was carried out on two Anthropomorphic Test Devices (ATDs) and nine PMHS.
Technical Paper

Investigation on Occupant Ejection in High Severity Rear Impact based on Post Mortem Human Subject Sled Tests

Occupant protection in rear impact involves two competing challenges. On one hand, allowing a deformation of the seat would act as an energy absorber in low severity impacts and would consequently decrease the risk of neck injuries. However, on the other hand, large deformations of the seat may increase the likelihood of occupant ejection in high severity cases. Green et al., 1987 analyzed a total of 919 accidents in Great Britain. They found that occupant ejection resulted in a risk of severe injuries and fatalities between 3.6 and 4.5 times higher than those cases where no ejection was observed. The sample included single front, side and rear impacts as well as multiple impacts and rollover. The rate of belt use in the sample was 50%. While this analysis included all forms of impact scenarios, nevertheless, it highlights the relative injury severity of occupant ejection.
Technical Paper

Study of Rib Fracture Mechanisms Based on the Rib Strain Profiles in Side and Forward Oblique Impact

Rib fractures constitute a good indication of severity as there are the most frequent type of AIS3+ chest injuries. In 2008, Trosseille et al. showed a promising methodology to exhibit the rib fracture mechanisms, using strain gauges glued on the ribs of Post-Mortem Human Subjects (PMHS) and developing a specific signal analysis. In 2009, they published the results of static airbag tests performed on 50th percentile male PMHS at different distances and angles (pure lateral and 30 degrees forward oblique direction). To complete these already published data, a set of 8 PMHS lateral and oblique impactor tests were performed with the same methodology. The rib cages were instrumented with more than 100 strain gauges on the ribs, cartilage and sternum. A 23.4 kg impactor was propelled at 4.3 or 6.7 m/s. The forces applied onto the PMHS at 4.3 m/s ranged from 1.6 kN to 1.9 kN and the injuries varied from 4 to 13 rib fractures.
Technical Paper

The Effect of Angle on the Chest Injury Outcome in Side Loading

Thoracic injury criteria and injury risk curves in side impact are based on impactor or sled tests, with rigid or padded surfaces while airbags are very common on current cars. Besides, the loading is generally pure lateral while real crashes or regulations can generate oblique loadings. Oblique tests were found in the literature, but no conclusion was drawn with regard to the effect of the direction on the injury outcome. In order to address these two limitations, a series of 17 side airbag tests were performed on Post Mortem Human Subjects (PMHS) at different severities and angles. The subjects were instrumented with accelerometers on the spine and strain gauges on the ribs. They were loaded by an unfolded airbag at different distances in pure lateral or 30 degrees forward. The airbag forces ranged from 1680 N to 6300 N, the injuries being up to 9 separated fractured ribs. This paper provides the test results in terms of physical parameters and injury outcome of the 17 subjects.
Technical Paper

Investigations on the Belt-to-Pelvis Interaction in Case of Submarining

This study focuses on the phenomenon of lap belt slip on the iliac spines of the pelvis, commonly named “submarining ”. The first objective was to compare the interaction between the pelvis and the lap belt for both dummies and Post Mortem Human Subjects (PMHS). The second objective was to identify parameters influencing the lap belt hooking by the pelvis. For that purpose, a hydraulic test device was developed in order to impose the tension and kinematics of the lap belt such that they mimic what occurs in frontal car crashes. The pelvis was firmly fixed on the frame of this sub-system test-rig, while the belt anchorages were mobile. Fourteen tests on four Post-Mortem Human Subjects (PMHS) and fifteen tests on the THOR NT, Hybrid III 50th and Hybrid III 95th percentile dummies were carried out. The belt tension was kept constant while a dynamic rotation was imposed on the belt anchorages.
Technical Paper

Thoracic Injury Investigation using PMHS in Frontal Airbag Out-of-Position Situations

Many studies have reported multiple rib fractures sustained by an Out-of-Position (OOP) driver subjected to a frontal airbag deployment, but the injury mechanisms and thresholds remain unclear. Two successive phases occur during the bag deployment: punch-out loading of the thorax, followed by a membrane effect (Horsch et al. 1990). The aim of this study was to investigate the thoracic injuries generated by each phase separately. Tests of nine post-mortem human surrogates (PMHS) were carried out on a static test bench using a driver side airbag module described by Petit et al. (2003). The steering wheel was replaced by a plate in order to increase the loading generated by the airbag. Three loading configurations were performed: membrane only, punch-out only, and both types combined. The membrane-only tests were performed with the thorax initially positioned at 13, 78 and 128 mm from the plate in order to vary the load magnitude.
Technical Paper

The Effects of Axial Preload and Dorsiflexion on the Tolerance of the Ankle/Subtalar Joint to Dynamic Inversion and Eversion

Forced inversion or eversion of the foot is considered a common mechanism of ankle injury in vehicle crashes. The objective of this study was to model empirically the injury tolerance of the human ankle/subtalar joint to dynamic inversion and eversion under three different loading conditions: neutral flexion with no axial preload, neutral flexion with 2 kN axial preload, and 30° of dorsiflexion with 2 kN axial preload. 44 tests were conducted on cadaveric lower limbs, with injury occurring in 30 specimens. Common injuries included malleolar fractures, osteochondral fractures of the talus, fractures of the lateral process of the talus, and collateral ligament tears, depending on the loading configuration. The time of injury was determined either by the peak ankle moment or by a sudden drop in ankle moment that was accompanied by a burst of acoustic emission. Characteristic moment-angle curves to injury were generated for each loading configuration.
Technical Paper

Laboratory Reconstructions of Real World Frontal Crash Configurations Using the Hybrid III and THOR Dummies and PMHS

Load-limiting belt restraints have been present in French cars since 1995. An accident study showed the greater effectiveness in thorax injury prevention using a 4 kN load limiter belt with an airbag than using a 6 kN load limiter belt without airbag. The criteria for thoracic tolerance used in regulatory testing is the sternal deflection for all restraint types, belt and/or airbag restraint. This criterion does not assess the effectiveness of the restraint 4 kN load limiter belt with airbag observed in accidentology. To improve the understanding of thoracic tolerance, frontal sled crashes were performed using the Hybrid III and THOR dummies and PMHS. The sled configuration and the deceleration law correspond to those observed in the accident study. Restraint conditions evaluated are the 6 kN load-limiting belt and the 4 kN load-limiting belt with an airbag. Loads between the occupant and the sled environment were recorded.
Technical Paper

Abdominal Response to High-Speed Seatbelt Loading

This study was conducted to address injury risk due to high-speed loading of the abdomen by a seatbelt during the pretension phase. Indeed, a better coupling of occupants to the structure of the vehicle in frontal impact can be achieved by a strong pretension of the lap belt. However, out of position considerations have to be taken into account in the development of pretension systems. In particular, when the lap belt is on the abdomen instead of the pelvis at the time of pretension, the penetration of the belt into the abdomen should not lead to injuries. Given the sensitivity of pyrotechnic pre-tensioners to the resistance that they encounter, it is important to have an understanding of the behaviors of both human and dummy abdomens in order to evaluate injury risk. These data are indispensable for the evaluation, with dummy tests, of the effects of pre-tensioners on occupants and for the estimation of the levels of injury risk.