Philippe Petit’s research while affiliated with Laboratory of Accidentology and Biomechanics and other places

The standard THOR-50M dummy is equipped with sensors to measure the abdomen deflection and assess the risk of abdominal injuries. Since 2016, the "ABdominal Injury and SUbmarining Prediction" (ABISUP) consortium has developed a pressure-measuring abdomen for the THOR-50M to predict abdominal injuries and submarining as a potential alternative to the current THOR-50M abdomen design. A new lower abdomen including Abdominal Pressure Twin Sensor (APTS) was designed and four identical prototypes were built and shipped to consortium member test houses. Numerous abdominal belt loadings replicating tests from the literature were carried-out to check the prototype biofidelity, sensitivity and define a pressure-based AIS3+ injury risk functions (IRFs). Two compression-based IRFs were defined using porcine test results from the literature[7]. Compressions were defined as the ratios between the abdomen deflection and the full abdominal depth, or between the abdomen deflection and the abdominal depth in front of the spine. The abdominal depth in front of the spine was used in an attempt to minimize possible differences between species. It was estimated using simple assumptions and led to compressions exceeding 100% in a few cases. Then transfer functions between THOR abdominal compressions Beillas 2 and pressures were applied to obtain the pressure-based IRFs. Twenty-five sled tests were performed to assess the new abdomen under various restraint conditions and to evaluate the relevance of the IRFs. The THOR-50M new abdomen showed similar or better biofidelity than the standard abdomen without modifying the dummy kinematics. The abdomen was sensitive to loading height and no damage to the APTS was encountered during tests. Relationships between THOR-50M mean APTS pressure and abdominal compressions were modelled using a 3 rd degree polynomial with 0.98 R². The IRF with a log-logistic distribution obtained the lowest Akaike Information Criterion. For the compression based on the full abdomen depth, the AIS3+ injury risks of 25%, 50% and 75% corresponded to APTS pressures of 133, 201 and 304 kPa, respectively. For the compression based on the abdomen in front the spine, the AIS3+ injury risks of 25%, 50% and 75% corresponded to APTS pressures of 108, 197 and 361 kPa, respectively. The new abdomen discriminated between the restraint conditions: lower pressures (between 90 and 190 kPa) were obtained when the lap belt remained below or on the ASIS and higher pressures (170 to 450 kPa) were obtained when the lap belt loaded the abdomen. Using the IRF, a risk up to 50% could be obtained without submarining, i.e. with the lap belt still engaging the ASIS. This is not consistent with a risk expected to be low for a proper restraint. Possible adjustments are discussed in the paper to decrease APTS sensitivity when the lap belt is positioned below or on the ASIS.

Inhalt Trends in der aktiven, passiven und integralen Sicherheit Sustainability: New Requirements for Passive Safety 1 Advanced Seat Belt Actuator Technology enabling next Level Occupant Safety 15 Gender discussion in vehicle safety - An overview of the consideration of subparts of the population in vehicle safety based on accident data analysis and current ATD development 37 Integrated Active and Passive Safety Protocol – A Feasibility Study with Human Body Models and Volunteers 55 Potentiale durch Insassenklassifizierung und -zustandserkennung Potentials and Limitations in Driver Health Monitoring 67 Kompakte 3D-Weitwinkel-Kamera zur Fahrzeuginnenraumüberwachung 83 Potentiale durch Insassenklassifizierung und -zustandserkennung Camera-Based Gender Estimation of Vehicle Occupants with Virtual Testing Using Synthetic Data 99 Occupant classification and crash severity detection enable individualized shoulder belt forces and improve NCAP ratings on rear seat 113 Neue Mobilitätskonzepte und Verkehrssicherheit Analyse des Realunfallgeschehens zur Ableitung von Sicherheitsanforderungen an Fa...

The knee is one of the regions of interest for pedestrian safety assessment. Past testing to study knee ligament injuries for pedestrian impact only included knees in full extension and mostly focused on global responses. As the knee flexion angle and the initial ligament laxity may affect the elongation at which ligaments fail, the objectives of this study were (1) to design an experimental protocol to assess the laxity of knee ligaments before measuring their elongation at failure, (2) to apply it in pairedknee tests at two flexion angles (10 and 45 degrees). The laxity tests combined strain gauges to measure bone strains near insertions that would result from ligament forces and a custom machine to exercise the knee in all directions. Failure was assessed using a four-point bending setup with additional degrees of freedom on the axial rotation and displacement of the femur. A template was designed to ensure that the two setups used the exact same starting position. The protocol was applied to six pairs of knees which were tested until the failure of all ligaments. In the laxity tests, a higher compliance of the knee was observed at 45 degrees compared to 10 degrees. Minimum lengths associated with the beginning of bone loading were also successfully identified for the collateral ligaments, but the process was less successful for the cruciate ligaments. The failure tests suggested increased elongation and length at failure for the ligaments and their bundles at 45°. This could be consistent with the higher compliance in static test, but the minimum lengths identified on the collaterals did not explain this difference during failure. The results highlight the possible relationship between position, laxity and elongation at failure in a lateral loading and provide a dataset including 3D coordinates of insertions to continue the investigation using a modelling approach. Perspectives are also outlined to improve upon the laxity determination protocol.

The Test Device for Human Occupant Restraint (THOR) is an advanced crash test dummy designed for frontal impact. Originally released in a 50th percentile male version (THOR-50M), a female 5th version (THOR-05F) was prototyped in 2017 (Wang et al., 2017) and compared with biofidelity sub-system tests (Wang et al., 2018). The same year, Trosseille et al. (2018) published response corridors using nine 5th percentile female Post Mortem Human Subjects (PMHS) tested in three sled configurations, including both submarining and non-submarining cases. The goal of this paper is to provide an initial evaluation of the THOR-05F biofidelity in a full-scale sled test, by comparing its response with the PMHS corridors published by Trosseille et al. (2018). Significant similarities between PMHS and THOR-05F were observed: as in Trosseille et al. (2018), the THOR-05F did not submarine in configuration 1, and submarined in configurations 2 and 3. The lap belt tension and seat forces were similar in magnitude. For configurations 2 and 3, the pelvis excursions were of the same order of magnitude between both human surrogates. However, significant differences were also observed: compared to the PMHS, the THOR-05F showed shoulder belt forces that were 1.6 to 2.1 times higher in magnitude, and lap belt force time histories that were delayed by 10 to 20 ms. In configuration 1, the chest and pelvis resultant accelerations of the dummy were delayed as well, and the pelvis excursion and rotation more than doubled that of the PMHS.

Current highly automated vehicle concepts include reclined seat layouts that could allow occupants to relax during the drive. The main objective of this study was to investigate the effects of seat pan and pelvis angles on the kinematics and injury risk of a reclined occupant by numerical simulation of a frontal sled test. The occupant, represented by a detailed 50th percentile male human body model, was positioned on a semi-rigid seat. Three seat pan angles (5, 15, and 25 degrees from the horizontal) were used, all with a seatback angle of 40 degrees from the vertical. Three pelvis angles (60, 70, and 80 degrees from the vertical), representing a nominal and two relaxed sitting positions, were used for each seat pan angle. The model was restrained using a pre-inflated airbag and a three-point seatbelt equipped with a pretensioner and a load limiter before being subjected to two frontal crash pulses. Both model kinematic response and predicted injury risk were affected by the seat pan and the pelvis angles in a reclined seatback position. Submarining occurrence and injury risk increased with lower seat pan angle, higher pelvis angle, and acceleration pulse severity. In some cases (in particular for a 15 degrees seat pan), a small variation in seat pan or pelvis angle resulted in large differences in terms of kinematics and predicted injury. This study highlights the potential effects of the seat pan and pelvis angles for reclined occupant protection. These parameters should be assessed experimentally with volunteers to determine which combinations are most likely to be adopted for comfort and with post mortem human surrogates to confirm their significance during impact and to provide data for model validation. The sled and restraint models used in this study are provided under an open-source license to facilitate further comparisons.

Obese vehicle occupants sustain specific injury patterns in case of accidents in which the interaction between the seat belt and the abdomen may play a role. This study aimed to collect geometrical characteristics and to investigate the mechanical responses of the abdomen of obese subjects. Four Post Mortem Human Subjects (PMHS) with BMI ranging from 31 to 46 kg/m2 were collected. CT-scans performed in the seated position revealed that the antero-posterior depth of the abdominal fold (from the inguinal region to the most anterior point of the abdominal surface) was much greater (170 mm max., 127 mm average) than the thickness of subcutaneous adipose tissues (85 max., 38 mm in average). Each PMHS was subjected to three infra-injurious antero-posterior belt pulls in a seated posture with a lap belt positioned (C1) superior to the umbilicus, (C2) inferior to the umbilicus, (C3) inside the abdominal fold between the abdomen and the thigh. During the C1 and C2 tests, the belt moved cranially, and the abdominal fold opened widely especially in C2. Forces remained below 1800 N, for maximum applied displacements ranging from 89 to 151 mm for C1 and C2, and 37 to 66 mm for C3. Finally, sled tests were conducted on two PMHS seated on a semi-rigid seat and restrained by a three-point belt equipped with pretensioners and a 3.5 kN force limitation at the shoulder. The first PMHS (BMI 39 kg/m2) was tested at 49 km/h (39 g peak) and sustained severe injuries (AIS 4 pelvis dislocation, AIS 3 bilateral femur fractures) attributed to the combined loading of the seat and lap belt force (about 11 kN and 7 kN, respectively). The second PMHS (BMI 46 kg/m2) was subjected to a 29 km/h test (8 g plateau) and sustained no injury. The lap belt slid inside the abdominal fold in the first case and deformed the lower abdomen in the second, providing limited restraint forces during that interaction and leading to a large body excursion for the first test. The results highlight the possible relevance of the abdominal fold at the abdomen thigh junction to model and study the restraint conditions of obese occupants using Human Body Models (HBM).

As developing finite element human body models for automotive impact is a time consuming process, morphing using interpolation methods such as kriging has often been used to rapidly generate models of different shapes and sizes. Kriging can be computationally expensive when many control points are used, i.e. for very detailed target geometry (e.g. shape of bones and skin). It can also lead to element quality issues (up to inverted elements) preventing the use of the morphed models for finite element simulation. This paper presents a workflow combining iterative subsampling and spatial subdivision methodology that effectively reduces the computational costs and allows generating usable models through kriging with hundreds of thousands of control points. As subdivision introduces discontinuities in the interpolation function that can cause distortion of elements on the boundaries of individual subdivision areas, algorithms for smoothing the interpolation over those boundaries are proposed and compared. Those techniques and their combinations were tested and evaluated in a scenario of weight change on the detailed male model of the Global Human Body Model Consortium: 234 777 control points were used to successfully morph the model in less than 15 minutes on an office PC. Open source implementation is provided.

In highly automated vehicles (HAVs), new seat configurations may be desirable to allow occupants to perform new activities. One of the current HAV concepts is the swiveled seat layout, which might facilitate communication between occupants. The main objective of this study was to investigate the effects of seat swiveling angles on occupant kinematics and injury risk predicted by a Human Body Model (HBM) during a frontal impact. A detailed 50th percentile male HBM (GHBMC M50-O) was subjected to two frontal crash pulses in a sled setup. The model was positioned on a semi-rigid seat and restrained using a pre-inflated airbag and a three-point seatbelt. Simulations included four seat swiveling angles (0, -10, -20, and -30 degrees), three occupant positions (Sedan driver, large VAN driver or Laptop user), two airbag initial locations (nominal or matching the head Y location), and the inclusion of lateral supports on the seat pan. The effects of the seat swiveling angle were similar for all occupant positions. With the airbag in the nominal location, higher seat swiveling angles led to a higher head lateral displacement and a higher risk of head injury, especially for the BrIC criterion. The Sedan driver position had higher BrIC and a larger head lateral excursion than the other two positions. This could be mitigated by aligning the airbag location with the head. Pelvic fractures were also predicted for the configurations with the highest swiveling angles. These fractures were limited by the use of seat pan lateral supports. Overall, the model responses were sensitive to both seating configurations and occupant postures, and the results suggest that swiveled seating may increase the injury risk, especially for the head and pelvis. However, simple countermeasures, such as adapted airbag location or adding lateral seat pan supports, seemed possible to mitigate the risk.