Crashworthiness Design Of Front Rails Of Automobiles Reinforced By Periodic Minimal Surfaces

The previous studies show that the energy absorption capacity(SEA)and the initial peak force(PCF)of the thin-walled front longitudinal beam are often antagonistic to each other.Compared with thin-walled tubes without internal reinforcement,multi-cell reinforced tubes often have greater advantages in improving energy absorption capacity.But it always comes with significant increase in the initial peak force,which affects the crashworthiness.Based on the additive manufacturing technology,three novel internally reinforced thin-walled square tube structures are proposed,which are reinforced by three different types of triply period minimal surfaces(TPMS).Compared with two traditional multi-cell square tubes,i.e.diagonally reinforced square tube and inner polygon reinforced square tube,the increase of initial peak force is effectively controlled while the specific energy absorption is increased.The main research results are as follows:(1)Considering the factors of modeling,manufacturing and optimization,three TPMS are selected to reinforce the tubes.By using SLM technology of metal 3D printing,the manufacture of test samples and models was realized,and crushing test was carried out.The simulation parameters of three TPMS reinforced tubes are set to lay the foundation for subsequent numerical analysis and optimization.(2)Comparing the crashworthiness of three TPMS reinforcement tubes with two traditional multi-cell square tubes under the same mass conditions.Using complex proportional evaluation method,it is found that when the initial peak force weight is higher than 0.6,the collision resistance of the three TPMS reinforcement tubes is better than that of the traditional reinforcement tubes,and when the isosurface surface parameter is 0,the P-TPMS reinforced tubes are always better than the other two TPMS reinforced tubes in the whole weight domain.(3)The relationships between geometric isosurface parameters C,structural thickness t,TPMS types and structural mass of three types of TPMS reinforced tubes are established.The fourth-order response surface models of SEA and PCF are established,and the data relationships and rules of C,t,TPMS types with initial peak force and specific energy absorption are analyzed.The results show that C only affects SEA of three TPMS reinforcement tubes,while t has significant effects on SEA and PCF in varying degrees.Finally,the NLPQL optimization method is used to optimize the three TPMS reinforced structures,which proves the feasibility of the optimization for TPMS reinforced tube.The three TPMS reinforcement tubes proposed in this paper have better crashworthiness than traditional multi-cell tubes under specified conditions.The feasibility and superiority of using complex TPMS as internal reinforcement of square tubes based on 3D printing technology are verified.Based on the geometric controllability of TPMS,multi-parameter and multi-objective methods adopted to the optimization of three TPMS are feasible and practical,and it can be extended to the optimization of different parameter ranges.