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Evaluation of Pedestrian Subsystem Test Method Using Legform and Upper Legform Impactors for Assessment of High-Bumper Vehicle Aggressiveness

In accidents involving sports utility vehicles (SUVs), injuries to pedestrian leg, knee ligaments, and femur are likely to occur. Therefore, the European Enhanced Vehicle Safety Committee proposed two subsystem test methods for evaluation of SUV bumper aggressiveness. Such evaluation can be conducted by means of either a legform impactor (evaluation of risk of knee and tibia injury), or an upper legform impactor (evaluation of risk of thigh and pelvis injury) test. Each of these two test methods has its own injury criteria and injury acceptance levels. Therefore, the first objective of this research is to clarify any differences between the test results obtained when evaluating SUV bumper aggressiveness by means of these two impactors. The second objective is to determine whether or not a legform impactor can be applied to estimate the risk of femur fracture, and if an upper legform impactor can be used to estimate the risk of knee ligament injury. The present results indicate the test method using an upper legform impactor yields higher ratios of injury criteria to the relevant EEVC/WG17 injury acceptance levels than by using a legform impactor. Thus, the upper legform impactor test rates an SUV bumper as more aggressive than the legform impactor test. The present study suggests the lower leg acceleration obtained by the legform impactor can be used to adequately assess the risk of femur fracture, when evaluating the aggressiveness of an SUV bumper using proposed injury acceptance levels reported in the literature. Similarly, the impact force obtained by the upper legform impactor can be used to assess the risk of cruciate ligament injury.