Validating Lower Limb Injury Mechanisms in Side Impact Crashes

Side-impact crashes are often segregated into nearside and far-side crashes because the injury mechanisms in these crash types differ. Most sideimpact research and regulations are based on nearside occupant injuries, but far-side occupants (Figure 1.B) can also incur serious harm. Near-side occupants are those which are situated on the same side as the impacted side of the vehicle (Figure 1.A). Moreover, side-impact regulatory crash tests in Australia are limited to one crash configuration (90°) and at one speed, 50 km/h. Lower extremity (LE) injuries sustained in side impact car crashes are debilitating due to the loss of weight bearing function and long rehabilitation times. In Australia such injuries rank third in terms of Harm after the head and thorax. Moreover, it is estimated around 20% of the total annual motor vehicle trauma treatment costs are devoted to rehabilitation of such injuries. Regulatory design rules protecting the knee, lower leg and ankle/foot in side-impact crashes do not exist. However, in order to adopt sensible mitigation strategies and appropriate design rules, it is essential to identify and validate injury mechanisms. In this study based on real-world crashes, injury mechanisms in three crash configurations were investigated. While considerable work has been carried out identifying lower limb injuries occurring in frontal crashes, little work has been carried out regarding side-impacts. Three injury mechanisms, identified from a real-world side-impact case-study analysis carried out at Monash University were proposed at a Melbourne crashworthiness conference in 2002 [2]. MADYMO computer models simulating nearand far-side occupants in three typical crash scenarios were constructed. Occupant kinematics and force outputs from the models were compared with the injuries and hence the mechanisms identified in the study. Figure 1.A A near-side occupant is on the struck-side of the target vehicle. After [40]. Results from the simulations were compared to published, known injury tolerances and are presented in this paper. Injury countermeasures for these three side-impact configurations are also discussed. Figure 1.B A far-side occupant is on the nonstruck side of the target vehicle. After [40]. Near-Side Occupant Injuries INTRODUCTION Researchers have found that near-side occupants are at greater risk than far-side occupants. There is little space between the occupant and the impacting object; i.e. there is a shorter vehicle exterior to occupant distance [42]. “A (near) side-impact collision is violent because the occupant is immediately struck by the door and the incoming car” [36]. Side-Impacts Side-impacts are the second most significant cause of serious injury and death after frontal-impact [16]. The cost of injury from side-impacts is high: 25% of vehicle casualties are from side-impacts and account for one third of occupant Harm on Australian roads [12]. Stolinski et al. [39] state that the annual cost of side-impacts in Australia has been estimated at around $870M per annum. The causes of near-side occupant injuries are varied and complicated. Injuries are dependent on the dynamic crush characteristics of the side door