Bionic Design And Crashworthiness Research Of Thin-walled Cellular Structures

Energy-absorbing devices are widely used in various vehicles,which can protect people and cargo in collision events.How to improve the crashworthiness of energy-absorbing devices has always been a hotspot of vehicle safety.Most creatures that survival through natural selection have excellent structure and function.The features of these biological structures can provide ideas to the researching of new energy absorption structures.In this study,we take triply periodic minimal surface(TPMS)and reed stems as the research subjects,applying the characteristics of these two structures to the design of thin-walled cellular structures to improve their crashworthiness.The main research contents of this article include the following aspects:(1)A novel sheet-based 3D cellular structure,called TPMS cellular structure,is investigated.The crashworthiness of four configurations of TPMS cellular structures is studied by experiments and numerical simulations.The effects of impact velocity,surface thickness t,and level-constant C on the crashworthiness of TPMS cel lular structures are investigated.Based on the simulation results,the multi-objective optimization of four types of TPMS cellular structures is realized using metamodels and the NSGA-II algorithm.Besides,the deformation modes of four types of TPMS cellular structures are analyzed.It is found that the deformation modes mainly depended on the topology of the TPMS units and are insensitive to the two design parameters t and C.(2)The microstructure characteristics of cross-section and longitudinal section of reed stem are studied.A novel type of thin-walled circular tube is designed based on these characteristics.The crashworthiness of this bionic thin-walled circular tube under bending loading and lateral impact loading is studied and compared with the traditional circular tube,square t ube,and other bionic structures in references using the finite element method.The results show that the thin-walled tube based on reed stem has better lateral crashworthiness than traditional tubes and other bionic thin-walled structures in references.Besides,the effects of unit angle ,partition distance l,and wall thickness t on the crashworthiness of bionic thin-walled tube is analyzed.The comprehensive evaluation of the simulation results is made by the complex proportional assessment method(CO PRAS).The evaluation results show that the bionic thin-walled structure with =6° and l=6 mm has the best crashworthiness among all configurations.(3)Combining the design ideas of above two thin-walled cellular structures,a TPMS-based bionic thin-walled tube is designed by replacing the 2D hexagonal units in the original bionic tube with 3D TPMS units.With the help of parameterized modeling platform Grasshopper in the design software Rhinoceros,the geometr ic model of six configurations of the TPMS-based bionic tube is constructed by the method of unit mapping.The crashworthiness of three configurations of TPMS-based bionic tube under lateral impact loading is studied by using finite element simulation software.The simula tion results show that the TPMS-D bionic tube with FRD configuration has the best crashworthiness.Its specific energy absorption is 2.90 times higher than that of the original bionic tube with unit angle=6° and partition distance l=6 mm.The results indicate that bionic design based on the structural characteristics of TPMS and reed stem can greatly improve the crashworthin ess of thin-walled structures.The sheet-based TPMS cellular structures and the bionic tubes based on the reed stem in this study have better comprehensive crashworthiness performance than other traditional structures,and have a good application prospect in the field of mechanical engineering.