Comparative study of potential whiplash injuries for different occupant seated positions during rear end accidents.

PURPOSE: Whiplash injuries to the cervical spine represent a considerable economic burden on society with medical conditions, in some cases persisting for more than a year. Numerous studies of whiplash injuries have been made for occupant normal seated position, leaving the analysis of neck injuries for out-of-normal positions not well documented. For that purpose, a detailed human cervical spine finite element model was developed. METHODS: The analysis was made for four most common occupant seated positions, such as: Normal Position with the torso against the seat back and the head looking straight ahead, Torso Lean forward position with the torso away from the seat back for approximately 10°, Head Flexed position with the head flexed forward approximately 20° from the normal position and Head-Flexed with Torso Lean forward position with the head flexed forward approximately 20° and torso 10° from the normal position. RESULTS: The comparative study included the analysis of capsular ligament deformation and the level of S-curvature of the cervical spine. The model developed predicted that Head Flexed seated position and Head-Flexed with Torso Lean forward seated position are most threatening for upper and lower cervical spine capsular ligament, respectively. As for the level of S-curvature, the model predicted that Head-Flexed with Torso Lean forward seated position would be most prone to neck injuries associated with it. CONCLUSIONS: This study demonstrated that the occupant seated position has a significant influence on potential whiplash injuries.

Impacts to the chest of PMHSs - Influence of impact location and load distribution on chest response.

The chest response of the human body has been studied for several load conditions, but is not well known in the case of steering wheel rim-to-chest impact in heavy goods vehicle frontal collisions. The aim of this study was to determine the response of the human chest in a set of simulated steering wheel impacts. PMHS tests were carried out and analysed. The steering wheel load pattern was represented by a rigid pendulum with a straight bar-shaped front. A crash test dummy chest calibration pendulum was utilised for comparison. In this study, a set of rigid bar impacts were directed at various heights of the chest, spanning approximately 120mm around the fourth intercostal space. The impact energy was set below a level estimated to cause rib fracture. The analysed results consist of responses, evaluated with respect to differences in the impacting shape and impact heights on compression and viscous criteria chest injury responses. The results showed that the bar impacts consistently produced lesser scaled chest compressions than the hub; the Middle bar responses were around 90% of the hub responses. A superior bar impact provided lesser chest compression; the average response was 86% of the Middle bar response. For inferior bar impacts, the chest compression response was 116% of the chest compression in the middle. The damping properties of the chest caused the compression to decrease in the high speed bar impacts to 88% of that in low speed impacts. From the analysis it could be concluded that the bar impact shape provides lower chest criteria responses compared to the hub. Further, the bar responses are dependent on the impact location of the chest. Inertial and viscous effects of the upper body affect the responses. The results can be used to assess the responses of human substitutes such as anthropomorphic test devices and finite element human body models, which will benefit the development process of heavy goods vehicle safety systems.

ADSEAT--Adaptive Seat to Reduce Neck Injuries for Female and Male Occupants.

Neck injuries sustained in low severity vehicle crashes are of worldwide concern and the risk is higher for females than for males. The objective of the study was to provide guidance on how to evaluate protective performance of vehicle seat designs aiming to reduce the incidence of neck injuries for female and male occupants. The objective was achieved by reviewing injury risk, establishing anthropometric data of an average female, performing dynamic volunteer tests comprising females and males, and developing a finite element model, EvaRID, of an average female. With respect to injury criteria, it was concluded based on the tests that using NIC (with a lower threshold value) and Nkm (with reduced intercept values) for females would be a suitable starting point. Virtual impact simulations with seats showed that differences were found in the response of the BioRID II and EvaRID models, for certain seats.