Filtern
Schlagworte
- Severity (accid, injury) (3) (entfernen)
Upcoming test procedures and regulations consider the use of Q-dummies. Especially Q6 and Q10 will be introduced to assess the safety of child occupants in vehicle rear seats. Therefore detailed knowledge of these dummies is important to improve safety. As recent studies have shown, chest deflection measurements of both dummies are influenced by parameters like belt geometry. This could lead to a non optimized design of child restraint systems (CRS) and belt systems. The objective of this study is to obtain a more detailed understanding of the sensitivity of chest measurements to restraint parameters and to investigate the possibilities of chest acceleration as an alternative for the assessment of chest injury risks. A study of frontal impact sled tests was performed with Q6 and Q10 in a generic rear seat environment on a bench. Belt parameters like modified belt attachment locations were varied. For the Q6 dummy, different positioning settings of the CRS (booster with backrest) and of the dummy itself were investigated. The Q10 dummy was seated on a booster cushion. Here the position of the upper belt anchorage point was varied. To simulate the influence of vehicle rotation in the ODB crash configuration, the bench was pre-rotated on the sled in additional tests with the Q10. This configuration was tested with and without pretensioner and load limiter. Chest deflection in Q6 showed a high sensitivity to changes in positioning of the CRS and the dummy itself. A more slouched position of the CRS or dummy resulted in a reduction of measured chest deflection, whereas chest acceleration increased for a more slouched position of the CRS. Chest deflection in Q10 is sensitive to belt geometry as already shown in other studies. In a more outboard position of the shoulder belt anchorage the measured chest deflection is higher. Chest acceleration shows the opposite tendency, which is highest for the rearmost location of the upper belt anchorage. On a pre-rotated bench the highest chest deflection within this test series was observed without load limiter/pretensioner and an outboard belt position. By optimizing the belt location and the use of pretensioner/load limier the chest deflection was significantly reduced. For the Q6 a criterion based on chest acceleration as well as deflection measured at two locations might be the most reliable approach, which requires further research with an additional upper deflection sensor. In the Q10 the measured chest deflection does not always correctly reflect the severity of chest loading. The deflection is depending on initial belt position and restraint parameters as well as test conditions, which result in different directions of belt migration. A3ms chest acceleration might be a better indicator for severity of chest loading independent of different conditions like belt geometries. However, in some cases the benefit of an optimized restraint system could only be shown by deflection. These findings suggest that further research is needed to identify a chest injury assessment method, which could be based on deflection as well as acceleration or other parameters related to belt to occupant interaction.
Thoracic injuries are one of the main causes of fatally and severely injured casualties in car crashes. Advances in restraint system technology and airbags may be needed to address this problem; however, the crash test dummies available today for studying these injuries have limitations that prevent them from being able to demonstrate the benefits of such innovations. THORAX-FP7 was a collaborative medium scale project under the European Seventh Framework. It focused on the mitigation and prevention of thoracic injuries through an improved understanding of the thoracic injury mechanisms and the implementation of this understanding in an updated design for the thorax-shoulder complex of the THOR dummy. The updated dummy should enable the design and evaluation of advanced restraint systems for a wide variety (gender, age and size) of car occupants. The hardware development involved five steps: 1) Identification of the dominant thoracic injury types from field data, 2) Specification of biomechanical requirements, 3) Identification of injury parameters and necessary instrumentation, 4) Dummy hardware development and 5) Evaluation of the demonstrator dummy. The activities resulted in the definition of new biofidelity and instrumentation requirements for an updated thorax-shoulder complex. Prototype versions were realised and implemented in three THOR dummies for biomechanical evaluation testing. This paper documents the hardware developments and biomechanical evaluation testing carried out.
Thorax injury is one of main causes of serious injury in frontal collisions, especially for elderly car occupants. The anthropometric test device (ATD) THOR‐M provides chest deflection measurements at multiple locations, to assess the risk of thorax injury. For this purpose e, risk functions are needed that relate the potential criteria based on multipoint chest deflection measurement to in jury risk. Different thorax injury criteria and risk functions for THOR have been proposed [2‐3]. The criteria and functions are based on the traditional approach to developing injury risk functions using matched ATD and PMHS tests by relating the injury (number of fractures) to injury criteria. Regarding these studies, some limitations have been identified, in particular concerning the loading conditions of the data used (mainly 3‐point‐belt loading, high loading severity, out‐of‐date ATD versions. To extend the data set and overcome these limitations, a new approach for improved thorax injury criteria was applied within the EC‐funded project SENIORS. The new approach is based on matched frontal impact sled computer simulations with a model representing the latest THOR‐M ATD version, and matching simulations with a human body model (HBM) representing an elderly car occupant.