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Accident studies show that frontal collisions, both as regards the number of people killed and those seriously-injured, are by far the type of crash with the most serious consequences. In order to improve this situation, it is necessary to ensure that the means used to restrain occupants work as efficiently as possible, whilst preserving the occupant compartment and thus by eliminating intrusion on the occupant restrained by seat-belts and pretensioners. In frontal collisions where vehicle intrusion is minor, the main lesions caused to occupantss are thoracic, mainly rib fractures resulting from the seat-belt. In collisions where intrusion is substantial, the lower members are particularly vulnerable. In the coming years, we will see developments which include more solidly-built cars, as offset crash test procedures are widely used to evaluate the passive safety of production vehicles.

Child restraint systems (CRS) for cars are intended to protect children in the case of a car accident. Unfortunately their effectiveness is still too low: in the range 30–50 % when it would be expected to be much higher. The low effectiveness of child restraint systems can partly be explained for the youngest passengers by their greater cervical vulnerability and for the oldest (from 3 to 12 years old) by the morphological immaturity of the pelvis. However, tools available to evaluate the effectiveness of CRS are very poor, as well as knowledge on injury mechanisms and criteria. The CREST project was created to develop the knowledge on child behaviour and tolerances, the final aim being to propose new test procedures for determining the effectiveness of CRS using instrumented child dummies. Eleven partners were involved, namely Fiat Auto-SpA (with Elasis), INRETS, PSA Peugeot Citroën, Renault, TNO Automotive, TUB, RICE, BAST, GDV, MUH, VTI.

Petit et al. 2015 and Lebarbé et al. 2016 reported on two studies where the injury mechanism and threshold of the sacroiliac joint were investigated in two slightly oblique crash test conditions from 18 Post Mortem Human Subjects (PMHS) tests. They concluded that the sacroiliac joint fractures were associated with pubic rami fractures. These latter being reported to occur first in the time history. Therefore it was recommended not to define a criterion specific for the sacroiliac joint. In 2012, injury risk curves were published for the WorldSID dummy by Petitjean et al. For the pelvis, dummy and PMHS paired tests from six configurations were used (n = 55). All of these configurations were pure lateral impacts. In addition, the sacroiliac joint and femur neck loads were not recorded, and the dummy used was the first production version (WorldSID revision 1). Since that time, the WorldSID was updated several times, including changes in the pelvis area.

This paper presents comprehensive dorsiflexion responses and tolerances obtained from two types of dynamic tests on whole cadavers conducted at the Renault/PSA Laboratory of Accidentology and Biomechanics (LAB): sled tests and sub-system tests. In all the experiments (on whole cadavers), forces and moments within the ankle joint were accurately measured by means of a custom-designed 6-axis load cell implanted in the tibia, leaving all surrounding musculature intact. The results derived from both the sled tests and the subsystem tests are very similar. Moment-rotation curves are provided for the ankle joint. The force in the Achilles tendon which is not directly measured is calculated using the forces applied to the foot and the forces measured in the tibia.

Numerous cadaver tests have been performed in the past to define the behaviour and tolerance of the thorax under side impact conditions. To take into account the various test conditions and measurements techniques or parameters, a lumped parameter model is used to reproduce these tests and thus to compute the protection criteria in the same way. The correlation between the calculated criteria and the observed injuries is then analysed as a basis for discussion of their consistency and relevance. The second part of the paper deals with the transposition of tolerance criteria to the Eurosid 1 dummy, using simulation tests under different conditions (impactor test, free-fall test, imposed velocity). The results show that this transposition depends on the test conditions, because of the limited biofidelity of the Eurosid 1 dummy.

The anatomical dimensions, inertial properties, and mechanical responses of cadaver leg, foot, and ankle specimens were evaluated relative to those of human volunteers and current anthropometric test devices. Dummy designs tested included the Hybrid III, Hybrid III with soft joint stops, ALEX I, and the GM/FTSS lower limbs. Static and dynamic tests of the leg, foot, and ankle were conducted at the laboratories of the Renault Biomedical Research Department and the University of Virginia. The inertial and geometric properties of the dummy lower limbs were measured and compared with cadaver properties and published volunteer values. Compression tests of the leg were performed using static and dynamic loading to determine compliance of the foot and ankle. Quasi-static rotational properties for dorsiflexion and inversion/eversion motion were obtained for the dummy, cadaver, and volunteer joints of the hindfoot.

In order to obtain data about human head tolerance, the APR Laboratory of Biomechanics has developed a specific methodology for volunteer boxers. These ones are used because they expose themselves, in their normal body activities, to direct head impacts similar in nature to those experienced by vehicle occupants under crash conditions. This paper describes the specific experimental technique that permits association of the severity of the blows, measured in terms of physical parameters, to corresponding physiological effects, measured in medical terms.

In view of the lack of data concerning child protection, an accidentological and experimental work was engaged. The goal of this international research involving experts from seven countries was two-fold: In one hand, to establish protection principles, gathering and analysing real crashes involving restrained children. In the other hand, to identify and to quantify injury mechanisms in order to increase knowledge on child tolerances. To realize this second part, real crash reconstructions were performed, in order to correlate observed injuries with recorded parameters on dummies. This paper mainly presents four real crashes with the corresponding reconstructions. A special analysis of injury mechanisms in relation with their respective pertinent parameters is then proposed.

Several studies, available in the literature, were conducted to establish the most relevant criterion for predicting the thoracic injury risk on the THOR dummy. The criteria, such as the maximum deflection or a combination of parameters including the difference between the chest right and left deflections, were all developed based on given samples of Post Mortem Human Subject (PMHS). However, they were not validated against independent data and they are not always consistent with the observations from field data analysis. For this reason, 8 additional PMHS and matching THOR tests were carried out to assess the ability of the criteria to predict risks. Accident investigations showed that a reduction of the belt loads reduces the risk of rib fractures. Two configurations with different levels of force limitation were therefore chosen. A configuration representing an average European vehicle was chosen as a reference.

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.

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.

As of toady, statutory crash test dummies take neither bracing nor passive muscular effect into account in the lower limb area. The influence of the lower extremity musculature is however arising as a major concern for the study of front seat occupant protection. The lower extremity prototype of the THOR dummy, including a model of the human plantarflexion actuator passive response, was tested in dynamic dorsiflexion. A dynamic test series was performed on Thor-Lx under test conditions similar to those used by Portier et al., 1996, on cadavers and Hybrid III dummy. The test setup imposed a dynamic dorsiflexion to the foot by means of a load exerted under the ball of the foot with no impact velocity. The Thor-Lx and Hill responses are compared to cadaver responses. It is important to note that as of today there are no data available to demonstrate that the passive resistance of the cadaver is equivalent to resistance of a tensed human.

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.

In the literature, injuries at the ischio or ilio pubic ramus level are reported to occur to approximately ¾ of the occupants injured at the pelvis during side impact. Assuming that the load going through the pubis was a good indicator of the ramus stress, the pubic force was widely accepted as a protection criterion for pelvic fractures on side impact dummies. However, no data regarding the actual loads going through the pubis is currently available in the literature for Post Mortem Human Subjects (PMHS) in dynamic conditions. The goal of this study was to determine pelvic biofidelity specifications in terms of load path, to evaluate the pertinence of the pubic force as a criterion, and to develop a pelvic injury risk curve as a function of the pubic force. For that purpose, a pubic load cell was developed for PMHS use, and 16 side impact tests were performed on 8 PMHS using boundary conditions similar to impactor tests and sled tests reported in the literature.

An ideal injury criterion should be predictive of the risk of injury across the range of loading conditions where it may be applied. The injury risk curve associated with this criterion should be applicable to all loading conditions. With respect to side impact, the injury risk curve should apply to pure lateral or oblique loading by rigid and padded walls, as well as airbags. Trosseille et al., (2009) reported that the number of fractured ribs was higher in pure lateral impact than in forward oblique interaction with an airbag. A good dummy criterion should be able to account for this difference. To evaluate various injury criteria with the WorldSID 50th and ES-2re dummies, the dummies were exposed to the same airbag loadings as the PMHS. The criteria measured in the dummy tests were paired with the rib fractures from the PMHS tests.

The Abdominal Pressure Twin Sensors (APTS) for Q3 and Q6 dummies are composed of soft polyurethane bladders filled with fluid and equipped with pressure sensors. Implanted within the abdominal insert of child dummies, they can be used to detect abdominal loading due to the belt during frontal collisions. In the present study - which is part of the EC funded CASPER project - two versions of APTS (V1 and V2) were evaluated in abdominal belt compression tests, torso flexion test (V1 only) and two series of sled tests with degraded restraint conditions. The results suggest that the two versions have similar responses, and that the pressure sensitivity to torso flexion is limited. The APTS ability to detect abdominal loading in sled tests was also confirmed, with peak pressures typically below 1 bar when the belt loaded only the pelvis and the thorax (appropriate restraint) and values above that level when the abdomen was loaded directly (inappropriate restraint).

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.

The development of the WorldSID 50th percentile male dummy was initiated in 1997 by the International Organisation for Standardisation (ISO/TC22/SC12/WG5) with the objective of developing a more biofidelic side impact dummy and supporting the adoption of a harmonised dummy into regulations. The dummy is currently under evaluation at the Working Party on Passive Safety (GRSP) in order to be included in the pole side impact global technical regulation (GTR). Injury risk curves dedicated to this dummy and built on behalf of ISO/TC22/SC12/WG6 were proposed in order to assess the occupant safety performance (Petitjean et al. 2009). At that time, there was no recommendation yet on the injury criteria and no consensus on the most accurate statistical method to be used. Since 2009, ISO/TC22/SC12/WG6 reached a consensus on the definition of guidelines to build injury risk curves, including the use of the survival analysis, the distribution assessment and quality checks.

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.

Despite the increasing knowledge of the thorax mechanics, the effects of inter-individual differences on the mechanical response are difficult to take into account. Several methods are available in the literature to refine the biofidelity corridors or to extrapolate them to other populations (eg: children, small females, large males). Because of the lack of concrete cases, the relevance of the assumptions is rarely investigated. In 2014, Baudrit et al. published data on thorax dynamic responses of small female and midsize male Post Mortem Human Subjects in side and forward oblique impact tests. The impactor mass was 23.4 kg for all the tests and the nominal impact speed was 4.3 m/s. The diameter of the rigid disk was 130 and 152 mm respectively for the small female specimens and for the midsize male specimens. The authors found that the maximum impact force was a function of the total body mass for each loading.