The objectives of this research are: (1) to determine possible injury-related factor(s) causing Abbreviated Injury Scale (AIS) 2+ injury in the human lower leg when exposed to a lateral impact simulating a pedestrian accident; (2) to evaluate the biofidelity of the current (2000) version of the TRL legform impactor; and (3) to propose injury reference value for estimation of the leg and knee joint injury risk by means of this legform impactor. Injury-related factors were statistically tested to determine factors causing leg fracture and knee joint ligament injury. Knee lateral force, knee bending moment, knee shear displacement, knee bending angle, leg acceleration, and impact force were analyzed as factors that could be injury related. Regarding tibia fracture, both the impact force and leg acceleration were found to be significant factors. For ligament injury, it was found that only the shearing displacement was indeed very likely to be a significant factor. The legform impactor was evaluated by comparing its responses with published experimental results obtained using post-mortem human subjects (PMHSs). The evaluation was done under two conditions: impact point 84 mm below the knee joint center (shearing tests), and impact point near the ankle area (bending tests). Two impact speeds were used: 5.56 m/s and 11.11 m/s. Impact force, shear displacement, and bending angle were applied to measure the legform impactor biofidelity. In general, the impactor responses were outside the biofidelity corridors determined using PMHSs. The exception was the impact force in the bending set-up at a speed of 5.56 m/s. Transfer coefficients were determined between the responses of the legform impactor and the human leg. Using these coefficients, an impact force of 6.9 kN and a shearing displacement of 7.9 mm are suggested as criteria for the 50-percentile risk of leg fracture and ligament injury with the impactor. For the covering abstract of the conference see ITRD E206605.
Abstract