A Study On The Crashworthiness Of Lotus Like Cellular Thin-walled Structure

China is a big country of automobiles.In recent decades,the number of automobiles is increasing day by day.Automobile safety accid ents are inevitable.Because of its good energy absorption performance,lightweight design requirements and low manufacturing price,metal thin-walled structure is widely used in vehicle anti-collision parts.However,traditional metal thin-walled structure will have defects such as unstable deformation and low energy absorption efficiency when impacted,so how to obtain more excellent thin-walled structure crashworthiness is imminent.In order to improve the crashworthiness of the metal thin-walled tube structure,two different types of thin-walled structures and their derived thin-walled structures are proposed based on the lotus rhizome with excellent mechanical properties as the bionic prototype,and the design and research of the bionic thin-walled tubes are carried out.Through the finite element simulation,the crashworthiness of the bionic multi cell thin-walled tube is analyzed and explored,and its multi-objective optimization design is carried out.Finally,the theoretical prediction model of the a verage impact load of the bionic multicellular thin-walled tube is proposed.This paper focuses on the following three aspects:(1)For the first time,lotus root stalk is proposed as the bionic prototype of metal thin-walled structure.Honeycomb like mult i cell thin-walled circular tube structure and multi-layer multi cell thin-walled circular tube structure with hierarchical characteristics are proposed,and the corresponding finite element simulation model is established.The validity of the finite eleme nt numerical analysis is verified by theoretical analysis.The finite element numerical simulation of lotus like honeycomb multi cell thin-walled structure and lotus like multi-layer multi cell thin-walled structure with different level characteristics is carried out,and the crashworthiness between different structures is compared.The results showed that the increase of cell number and the hierarchical characteristics of lotus stem could improve the crashworthiness of the structure.(2)In order to further improve the crashworthiness of the lotus like honeycomb multi cell thin-walled circular tube,firstly,the geometric parameters and thickness parameters of the lotus like multi cell thin-walled structure are studied.It is found that the geometric parameters and thickness parameters of the cell circular tube and the thickness parameters of the connecting plate have an important influence on the crashworthiness of the structure,during which the maximum energy absorption ratio of the structure reaches 51.74 k J/kg.Then,according to Kriging agent model and multi-objective particle optimization algorithm,the multi-objective optimization design of lotus like honeycomb multi cell thin-walled circular tube structure with hierarchical characteristics is carried out,and the structural configuration parameters with optimal crashworthiness are obtained.(3)Based on the simplified super folded element theory,the theoretical prediction model of the average impact force of lotus like honeycomb multi cell thin-walled structure is derived.At the same time,the results of the theoretical prediction model are compared with the results of the corresponding finite element numerical simulation.The results of the theoretical prediction model are highly consistent with the results of the finite element analysis,which proves that the theoretical prediction model has high reliability.