Search Results

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.

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.

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.

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.

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.

This study aims to investigate the relationship between the number of rib fractures and the thoracic deflection in side impact, and in particular its variability with respect to various loading configurations. The relevance of thoracic deflection as an injury criterion depends on the existence or not of this variability. Few studies were dedicated to this issue in the literature. First, a validation database was established, which covers different impact directions (frontal, lateral and oblique), different loading types (impactor, belt and airbag), and different injury levels (from the absence of, to presence of numerous ribs fractured). The HUMOS human body model was then modified and validated versus the database. Besides the typical validation in terms of global response, particular attention was paid to validate the model with respect to the ribcage strain profile, the occurrence of rib fractures and their locations.

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.

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.

Sled tests focused on pelvis behavior and submarining can be found in the literature. However, they were performed either with rigid seats or with commercial seats. The objective of this study was to get reference tests to assess the submarining ability of dummies in more realistic conditions than on rigid seat, but still in a repeatable and reproducible setup. For this purpose, a semi-rigid seat was developed, which mimics the behavior of real seats, although it is made of rigid plates and springs that are easy to reproduce and simulate with an FE model. In total, eight PMHS sled tests were performed on this semi-rigid seat to get data in two different configurations: first in a front seat configuration that was designed to prevent submarining, then in a rear seat configuration with adjusted spring stiffness to generate submarining. All subjects sustained extensive rib fractures from the shoulder belt loading.

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.

For several years now, car manufacturers have made significant efforts in the field of thoracic protection. After first limiting the forces in the shoulder belt to 6 kN, these forces are now usually limited to 4 kN, with airbags intentionally designed to absorb the surplus of energy. If this technology is rewarded by a considerable improvement in safety on the road, it remains penalized by the usual biomechanical criteria, when calculated on the Hybrid III and if applied to all restraint systems. To remedy this problem a new criterion, valid in all the current restraint configurations (belt, airbag only or airbag and belt) is proposed. It is based on the measurement of the shoulder belt forces and of the central deflection and consequently is directly applicable to the current dummy model (Hybrid III). The use of shoulder belt forces allows the separation of the belt and airbag contributions to the deflection.

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.

As more and more active restraint devices are added by vehicle manufacturers for occupant protection, the history of driver frontal airbags illustrates that the design performance of such devices for in-position (IP) occupants often have to be limited in order to reduce their aggressiveness for out-of-position (OOP) situations. As of today, a limited number of publications dealing with FE simulation of airbag deployment for OOP are available. The objective of our study was to evaluate the feasibility of airbag deployment simulations based on an extensive set of well-defined physical test matrix. A driver frontal airbag was chosen (European mid-size car sample) for this study. It was deployed against a force plate (14 tests in a total of 6 configurations), and used with Hybrid III 50th percentile dummy (HIII) in OOP tests (6 tests, 4 configurations). Special attention was paid to control the boundary conditions used in experiments in order to improve the modelling process.

Rib fractures are the most frequent types of AIS3+ chest injuries and constitute a good indication of severity. However, the behavior of the rib cage is not well documented, and though chest external measurements are often provided in the literature, the strains of the ribs themselves during a crash remain unknown. In order to address this issue, a test protocol was developed, where the ribs of 8 PMHS were equipped with up to 96 strain gauges. In a first series of 3 tests, the subjects were seated upright and their chests were loaded by a 23.4 kg impactor propelled at 4.3 m/s in 0° (pure frontal), 60° (oblique) and 90° (pure lateral) directions. In a second series of 3 tests, the subjects were loaded by the deployment of an unfolded airbag in the same 3 directions. Finally, a third series of 2 tests was performed with airbags at different distances from the subjects, in a pure lateral direction. This paper presents the results of the tests and an analysis of the strain patterns.