| Human head injury is easy to cause fatal injury,and the important cause of pedestrian head fatal injury is the collision between pedestrian head and hood of a car,so the reasonable design of hood can help to reduce the degree of injury to the pedestrian's head during a collision,therefore,the research of the hood to pedestrian safety protection is of great significance.With the rapid development of automobile technology,v arious new car hoods have been put forward,and all have achieved good pedestrian protection effect.In these new hoods,the sandwich structure hood not only has a good pedestrian head protection effect,but also can improve the energy absorption effect wh ile reducing the hood quality,so it has a very good reference prospect in practical applications.However,the sandwiches of these new sandwich construction hoods currently studied are mainly foam materials,and there is no relevant research on the hood o f the three-dimensional lattice structure material,and the lattice structure has a better cushioning effect than foam materials,and its buffer performance is also relatively stable.Therefore,a new lightweight minimized curved lattice structure hood is proposed in this paper and the following research works have been carried out:(1)Based on the national standard GB/T 24550-2009,the pedestrian head impactor was built by using finite element simulation software such as LS-DYNA and HYPERMESH.In addition,the vehicle model,which will be used in the research work,is complex and involves multiple nonlinear mechanical problems such as material nonlinearity and contact nonlinearity.Therefore,it is difficult for the simplification of the vehicle model,and the simplification of the vehicle model,the definition of boundary condition and contact condition are all difficult.In this pa per,the whole vehicle model with high precision and good stability is obtained by several adjustments and verification.(2)A new lattice material named three period minimization surface(TPMS)lattice structure is proposed.Because the structure is made u p of three dimensional minimized surfaces,and it is called the three period minimization of the dot matrix structure.In this paper,the nonlinear finite element method based on LS-DYNA is used to study the crashworthiness of four configurations of lattice structures,and the influence of three variables on the crashworthiness of the four kinds of lattice configurations of TPMS lattice is compared and analyzed.The optimization design method based on the Kriging approximation metamodel and the non-dominated sorting genetic algorithm(NSGA)is used to optimize the simulation results of the finite element simulation.In the optimization design,the Kriging approximation metamodel is used to replace the finite element analysis with high computation cost,so as to improve the computation efficiency.(3)The optimal TPMS lattice structure is used to construct a new type of engine hood.The nonlinear finite element analysis method based on LS-DYNA is used to compare the pedestrian head protection performance of the conv entional hood and the new type of engine hood.The results show that the new type of engine hood constructed by TPMS dot matrix structure has very good pedestrian protection performance.The results of this paper show that the TPMS lattice structure h as very good crashworthiness.It can reduce the cost and reduce the quality while improving the crashworthiness performance.It has high potential for engineering application.In addition,the pedestrian safety protection performance of the new car hood is much better than that of the traditional engine hood.The application of the car has a good application prospect. |
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