The Research On The Evaluation Standard Of Advanced Pedestrian Legform Impactor Based On Pedestrian Lower Limb Injury Risk

With the increase in car ownership,road traffic safety problems are also increasing.In car-pedestrian collision accidents,pedestrians are often injured due to lack of protective facilities.The lower limbs of pedestrians are the most vulnerable parts after the head.Unlike pedestrian head injury,pedestrian lower limb injury often brings enormous economic problems and social burdens to society and families because of its high disability rate.In order to improve the collision protection ability of automobiles against pedestrians,it is indispensable to conduct adequate pedestrian protection testing before the new car is released.Regarding pedestrian lower leg protection test,the 2021 C-NCAP began to use aPLI to replace the TRL or Flex-PLI.In order to explore the rationality of the aPLI performance value,the aPLI evaluation standard based on the risk of pedestrian lower limb injury was carried out in this paper.In this paper,three different types of cars were selected for crash simulation test,the models were appropriately simplified,and the THUMS was adjusted to the stride attitude and the height above the ground was increased by 25 mm to simulate the real pedestrian collision attitude and height.And then,the simplified vehicle models were combined with the THUMS and the aPLI to establish a car crash simulation.Each car’s crash simulation was set up at seven positions from L0 to L6,and the crash speed was 40 km/h.The crash results output the femoral bending moment,tibial bending moment,and MCL elongation of the THUMS and aPLI.Then,the performance value of the THUMS was determined by the injury risk curve of the lower limb,and the performance value of the aPLI was proposed by the method of linear regression analysis.Finally,the rationality of the performance value was analyzed by the boxplot method.The study showed that at 19% and 30% risk of thigh injury for pedestrians,the femoral bending moment was 307 Nm and 334 Nm.The tibial bending moments at14% and 29% risk of lower leg injury were 284 Nm and 327 Nm.At 25% and 60%knee injury risk,the MCL elongation was 13.21 mm and 16.88 mm.The high-performance value of the aPLI was 411 Nm,and the low-performance value was446 Nm;the high-performance value of the sedan model was 357 Nm,and the low-performance value was 372 Nm;the high-performance value of the SUV model was 421 Nm,and the low-performance value is 439 Nm.The high-performance value of the lower leg of the aPLI was 426 Nm,and the low-performance value was 484 Nm;the high-performance value of the sedan model was 416 Nm,and the low-performance value was 476 Nm.Since the lower leg collision injury risk of SUV models was far less than 14%,the median 254 Nm in boxplot analysis was used as the high-performance value of the lower leg,and the 75 th percentile 299 Nm as the low-performance value.In terms of MCL elongation,since there is no significant difference between the THUMS model and the aPLI simulation results,the median of the boxplot analysis was 22.87 mm as the high-performance value,and the 75 th percentile was 26.91 mm as the low-performance value.The high-performance value of the sedan was 25.50 mm,and the low-performance value was 31.41 mm;the high-performance value of the SUV was 20.90 mm,and the low-performance value was 24.70 mm.The aPLI evaluation standard given in this paper was related to the risk of pedestrian lower limb injury,and can be used to evaluate the pedestrian protection performance of automobiles more objectively.