| With the increasing number of cars in the world,the incidence of traffic accidents is also rising,and pedestrians as vulnerable groups of road users are vulnerable to casualties caused by accidents.According to statistics,the probability of injury to the lower limbs of pedestrian injuries is as high as 30%.At present,the study of the front structure of the vehicle based on the leg type test is an important research direction to improve the protection performance of the lower limbs of the pedestrian of the vehicle.A large number of studies have been carried out on the front structure of vehicles based on Flex-PLI leg type at home and abroad,but as the latest aPLI leg type begins to be included in various evaluation procedures,the impact of vehicle front-end structure parameters on the damage value of aPLI leg type has been less studied.Clarifying the influence of vehicle front-end structure parameters on aPLI leg type damage value can provide data support for vehicle front-end structure design,thereby improving the vehicle’s pedestrian lower limb protection performance.The purpose of this paper is to explore the influence of vehicle front-end structure parameters on the damage value of aPLI leg type,and to find the optimal combination of vehicle front end structure parameters with the lowest aPLI leg type damage value based on the evaluation procedures of the 2021 edition of C-NCAP pedestrian leg test.Through the important structure of the impact of the front end of the car on the aPLI damage during the collision impact,combined with the literature research,the structural characteristic parameters of the front end of the car that have a greater impact on the damage value of the aPLI are determined,and the range of the characteristic parameters of the various Sedans and SUVs is collected respectively.According to the characteristic parameters,the simplified model of the front end of the car is established,and the effectiveness of the simplified model is verified by comparing the collision simulation results with the complete model of the front end.Based on the model,the sensitivity of the front-end structure parameters of the sedan and the SUV are analyzed based on the aPLI damage value.Take Latin hypercube sampling,obtain the experimental matrix,modify the simplified model according to the experimental matrix and submit the calculation.The aPLI damage response value is collected,and an approximate model is established,and the effectiveness of the approximate model is verified by error analysis.Through the approximate model,the contribution degree diagram,interaction three-dimensional response surface diagram and contour line diagram are used to analyze the front-end structural parameters of Sedan and SUV.The NSGA-II algorithm is used to optimize the design of the approximate model,and the optimal combination of front-end structural parameters based on the Sedan and SUV is obtained with the goal of reducing the damage value of aPLI,and applies it to the Camry and Rogue models.The results of the study showed that the ground height of the middle support of the Sedan had the greatest impact on the thigh injury value,and the lower support offset distance had the greatest impact on the calf and knee injury value.The lower support offset distance of the SUV has the greatest impact on the value of thigh,calf,and knee injuries.The optimization application results show that for Sedan,the maximum bending moment of the thigh,the maximum bending moment of the lower leg,and the reduction of the Elongation of the MCL were 19.8%,40.3%,and 56.0%,respectively,and the score was increased from 2 points to 5 points.For SUV: the decline rates were 26.3%,14.2%,and 49.3%,respectively,and the score increased from 1.1 points to 4.9 points close to the full score.The results show that the optimal combination of front-end structural parameters of Sedans and SUVs has good pedestrian lower limb protection performance,and the simplified model established provides data support for the study of the lower limb protection performance of automobile pedestrians,and provides certain reference significance for automobile front-end structural parameters and modeling design. |
