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One main objective of the EU-Project SENIORS is to provide improved methods to assess thoracic injury risk to elderly occupants. In contribution to this task paired simulations with a THOR dummy model and human body model will be used to develop improved thoracic injury risk functions. The simulation results can provide data for injury criteria development in chest loading conditions that are underrepresented in PMHS test data sets that currently proposed risk functions are based on. To support this approach a new simplified generic but representative sled test fixture and CAE model for testing and simulation were developed. The parameter definition and evaluation of this sled test fixture and model is presented in this paper. The justification and definition of requirements for this test set-up was based on experience from earlier studies. Simple test fixtures like the gold standard sled fixture are easy to build and also to model in CAE, but provide too severe belt-only loading. On the other hand a vehicle buck including production components like airbag and seat is more representative, but difficult to model and to be replicated at a different laboratory. Furthermore some components might not be available for physical tests at later stage. The basis of the SENIORS generic sled test set-up is the gold standard fixture with a cable seat back and foot rest. No knee restraint was used. The seat pan design was modified including a seat ramp. The three-point belt system had a generic adjustable load limiter. A pre-inflated driver airbag assembly was developed for the test fixture. Results of THOR test and simulations in different configurations will be presented. The configurations include different deceleration pulses. Further parameter variations are related to the restraint system including belt geometry and load limiter levels. Additionally different settings of the generic airbag were evaluated. The test set-up was evaluated and optimized in tests with the THOR-M dummy in different test configurations. Belt restraint parameters like D-ring position and load limiter setting were modified to provide moderate chest loading to the occupant. This resulted in dummy readings more representative of the loading in a contemporary vehicle than most available PMHS sled tests reported in the literature. However, to achieve a loading configuration that exposes the occupant to even less severe loading comparable to modern vehicle restraints it might be necessary to further modify the test set-up. The new generic sled test set-up and a corresponding CAE model were developed and applied in tests and simulations with THOR. Within the SENIORS project with this test set-up also volunteer and PMHS as well as HBM simulations are performed, which will be reported in other publications. The test environment can contribute in future studies to the assessment of existing and new frontal impact dummies as well as dummy improvements and related instrumentation. The test set-up and model could also serve as a new standard test environment for PMHS and volunteer tests as well as HBM simulations.
From an automotive safety occupant protection standpoint, effective occupant restraint requires a system capable of providing non-injurious occupant ride down of anticipated crash forces. This is not only the case for frontal collisions, where occupant restraint is provided primarily by seatbelts and airbags, but is also critical for other crash modes such as side impacts, rear impacts, rollovers, as well as multiple impact events. In the rear impact crash mode, occupant restraint is provided primarily by the seatbacks and to some extent the seatbelts. Foundationally, therefore, what becomes fundamental to the seatback's role in rear occupant protection is its ability to contain the occupant within the seat, preventing occupant ramping, as well as preventing the seat's, and/or its occupant's, dangerous intrusion into the rear occupant's survival space where contact with rear compartment components and/ or rear seated occupants can present a significant injury risk. An analysis is presented of a series of rear impact sled testing conducted by the authors that evaluates the timing, position and extent of the front seatback's reward displacement toward and into the rear occupant compartment as well as consideration of the front seat occupant' ramping potential and its injury potential relative to the rear compartment. Additionally, three other series of testing are presented which assess various seat designs occupant retention capabilities. Lastly, a matched-pair comparison test series is presented which evaluates occupant motion in rear impact with and without use of a typical vehicle body mounted 3-point seatbelt. Discussion of restraint system performance observed in all the testing is included along with ATD biofidelity and thigh-gap considerations. The data collected and presented includes accelerometer instrumentation and high speed video analysis.
The United Nations Economic Commission for Europe Informal Group on GTR No. 7 Phase 2 are working to define a build level for the BioRID II rear impact (whiplash) crash test dummy that ensures repeatable and reproducible performance in a test procedure that has been proposed for future legislation. This includes the specification of dummy hardware, as well as the development of comprehensive certification procedures for the dummy. This study evaluated whether the dummy build level and certification procedures deliver the desired level of repeatability and reproducibility. A custom-designed laboratory seat was made using the seat base, back, and head restraint from a production car seat to ensure a representative interface with the dummy. The seat back was reinforced for use in multiple tests and the recliner mechanism was replaced by an external spring-damper mechanism. A total of 65 tests were performed with 6 BioRID IIg dummies using the draft GTR No.7 sled pulse and seating procedure. All dummies were subject to the build, maintenance, and certification procedures defined by the Informal Group. The test condition was highly repeatable, with a very repeatable pulse, a well-controlled seat back response, and minimal observed degradation of seat foams. The results showed qualitatively reasonable repeatability and reproducibility for the upper torso and head accelerations, as well as for T1 Fx and upper neck Fx. However, reproducibility was not acceptable for T1 and upper neck Fz or for T1 and upper neck My. The Informal Group has not selected injury or seat assessment criteria for use with BioRID II, so it is not known whether these channels would be used in the regulation. However, the ramping-up behavior of the dummy showed poor reproducibility, which would be expected to affect the reproducibility of dummy measurements in general. Pelvis and spine characteristics were found to significantly influence the dummy measurements for which poor reproducibility was observed. It was also observed that the primary neck response in these tests was flexion, not extension. This correlates well with recent findings from Japan and the United States showing a correlation between neck flexion and injury in accident replication simulations and postmortem human subjects (PMHS) studies, respectively. The present certification tests may not adequately control front cervical spine bumper characteristics, which are important for neck flexion response. The certification sled test also does not include the pelvis and so cannot be used to control pelvis response and does not substantially load the lumbar bumpers and so does not control these parts of the dummy. The stiffness of all spine bumpers and of the pelvis flesh should be much more tightly controlled. It is recommended that a method for certifying the front cervical bumpers should be developed. Recommendations are also made for tighter tolerance on the input parameters for the existing certification tests.
Das Ziel der Untersuchung war, die Grenzen der Belastbarkeit eines Rollstuhl- und Personenrückhaltesystems mit Kraftknoten nach DIN 75078-2 zu ermitteln. Dazu wurden dynamische Schlittenversuche durchgeführt, bei denen die Verzögerungspulse sowie das Gesamtgewicht von Rollstuhl und Prüfpuppe variiert wurden. Für die Untersuchungen kamen ein Prüfrollstuhl, definiert nach ISO 10542, und Rückhaltesysteme mit Kraftknoten gemäß DIN 75078-2 zum Einsatz. Das Rückhaltesystem bestand aus einem Rollstuhl- und einem Personenrückhaltesystem, wobei das Rollstuhlrückhaltesystem (RRS) mit vier bzw. sechs Gurten und entsprechenden Retraktoren an einem dynamischen Schlittenaufbau befestigt wurde. Das Personenrückhaltesystem (PRS) bestand aus einem am Rollstuhl integrierten Beckengurt sowie einem Schulterschräggurt, der am Beckengurt und am Schlittenaufbau befestigt wurde. Ferner wurden bei den Versuchen Prüfpuppen verschiedener Alters- und Gewichtsklassen (P6, HIII 5 %, HIII 50 % und HIII 95 %) eingesetzt Die Belastungsanforderungen für das Rückhaltesystem wurden sukzessiv erweitert, indem einerseits das Gesamtgewicht (Rollstuhl und Prüfpuppe) und andererseits auch die Verzögerungspulse bis zur Versagensgrenze erhöht wurden. Das Vier-Gurt-Rückhaltesystem konnte bei einem Verzögerungspuls von 10 g einem Gesamtgewicht von bis zu 221 kg standhalten. Bei einem Verzögerungspuls von 20 g und einem Gesamtgewicht von 134 kg wurde das Vier-Gurt-System bis über die Grenzen belastet. Das Sechs-Gurt-Rückhaltesystem hat Belastungen bis 221 kg standgehalten. Infolgedessen ist bei einer Erhöhung der Verzögerungspulse auf 20 g und einem Gesamtgewicht von mehr als 109 kg ein Sechs-Gurt-System zu empfehlen.
Rollovers continue to be a major source of heavy truck fatalities when compared to other accident modes. Real world rollover accidents are analyzed and two distinct damage patterns are identified. Damage to heavy truck roofs can occur from lateral loading that transitions to vertical roof loading as the vehicle rolls onto its side and then over onto its roof. A second load path can occur when the vehicle has rolled onto its side and furrows into the ground generating large longitudinal friction forces between the roof and ground. A review of the previous literature and various test methodologies are presented. A sled impact test methodology is presented which allows for structural assessment of a heavy truck cab's crashworthiness in both of these loading environments. Two test series are presented using the sled impact test methodology in order to analyze real world truck rollovers using varying impact platen and contact angles. The structural deformation and failure patterns were found to be consistent with damage seen in real world accident vehicles. In each case, a second equivalent truck cab was then reinforced and tested under similar conditions to evaluate the energy management and crush resistance of a stronger cab structure. These structural reinforcements demonstrated a substantial reduction in roof crush and protected the survival space of the occupant compartment. The sled impact test procedure is an effective method for testing the structural performance of a heavy truck cab in a variety of loading scenarios comparable to real world accidents and ascertaining the load and energy load levels in these accident modes.