Research On Optimization Of The Automobile Engine Hood System’s Performance Considering Pedestrian Head Protection And Lightweight Design

When a pedestrian is hit by a high-speed car,the pedestrian’s head will hit the hood,causing Head Injury.Optimizing the hood system to reduce Pedestrian Head Injuries is a worth studying topic.In the Lightweight Design,due to changes in the structure and parameters of the hood,the safety performance of pedestrian head protection may be reduced.This article takes the automobile hood system of a certain brand as the research object,and takes into account the protection of pedestrians’ heads,and makes a Lightweight Design of the automobile hood system.Combining materials selection,structure optimization,parameter optimization,a systematic and efficient research theory is proposed,which greatly reduces the development cycle and reduces the design and development costs.First of all,establish a finite element model of the head impactor and hood system,mount it in a half-car model and establish a finite element model of pedestrian head collision.According to the different collision areas,it is divided into adult and child collision areas,and 8 key test points are selected.After the test verification analysis,the pedestrian head collision model is accurate and reliable.The head protection performance analysis of the initial hood model shows that the HIC values of the key test points are generally high,and the head impact score is only 6.600 points.Secondly,the Opti Struct software is used to perform static stiffness and modal analysis on the hood system to determine the stiffness value and maximum stress of the initial hood system under forward bending,lateral bending,and torsion.To avoid resonance,the system needs to be determined natural frequency.The results show that the maximum stress of the initial hood under forward bending is greater than the yield strength of the material,which does not meet the design requirements.Through multi-objective topology optimization,improve structure and redesign hood inner panel.It is verified that the updated hood system’s static stiffness performance meets the design requirements,but among the eight key test points,the HIC values at test points A12,7 and C3,0 increase,and pedestrian safety performance needs to be improved.Taking these two key test points as the key optimization targets,the system parameters are optimized.Finally,taking the hood outer panel material,inner panel material,outer panel thickness,inner panel thickness,lid lock reinforcement panel thickness,hinge thickness as the influence factors,the output parameter index is based on the hood system stiffness,modal,mass,HIC values of test points A12,7 and C3,0.Design the sensitivity test,and analyze the results to determine the key parameters and their value range.Then,a suitable approximate model is constructed to replace the simulation model,and a deterministic optimization scheme is obtained through multi-objective parameter optimization.The results show that the static stiffness performance of the optimized hood system still meets the design requirements.The HIC values of the eight key test points are all reduced,of which the HIC values of the test points A12,7 and C3,0 decreased by 5.98% and 16.76%,respectively.The collision simulation score is 8.006 points,pedestrian head protection performance is significantly improved.The system quality is reduced by 33.34%,and the lightweight design goal is reached.