Crushing Analysis And Optimization For Bio-inspired Hierarchical 3D Cellular Structure

The porous structure is widely used in personal protection,aerospace,automotive and other fields.The Triply Periodic Minimal Surface(TPMS)as a three-dimensional lattice structure has a more uniform mechanical properties than foam structure.The TPMS lattice structure has a good application prospect in the field of impact engineering due to its light,high strength and strong energy absorption characteristics.It was found that many biological structures in nature have hierarchical structure characteristics,which often make them show excellent mechanical properties,so that they can better adapt to the natural environment.Based on the two points,in this paper,a hierarchical structure based on TPMS was proposed.The method of designing hierarchical structure.The implicit function expression of TPMS hierarchical structure is obtained by SF surface splicing method.The 3D STL file of TPMS hierarchical structure is generated by Mathmod software and imported into Hypermesh software for mesh generation,so as to obtain the hierarchical structure finite element model.Finite element model validation.In order to verify the reliability and effectiveness of the finite model,we have prepared the hierarchical structure sample based on 316 L stainless steel by 3D printing technology,and carried out quasi-static compression experiment on the universal testing machine.By comparing the experimental results with the finite element calculation results,it was found that the finite element model of hierarchical structure has certain reliability and can be used for the subsequent crashworthiness research.Research on crashworthiness of hierarchical structure.In this paper,the influence of the density,constant C of first order structure and side length ratio of the hierarchical structure on its crashworthiness is studied,and the deformation mode of the structure is analyzed and discussed.In order to obtain the optimal crashworthiness design parameters of the structure,we combined Kriging surrogate model and genetic algorithm to optimize the hierarchical structure.In addition,we also compared the energy absorption characteristics of hierarchical structure and non hierarchical structure,and found that hierarchical structure has better crashworthiness in a certain range.Theoretical analysis and equivalent model.In this paper,the expression of SEA is given by fitting Gibson’s empirical formula.After verification,it is found that the error of the expression is less than 10%,which has good accuracy.At the same time,in order to simplify the calculation,we study various low-density foam constitutive to replace the complex hierarchical structure for calculation.Through comparison,we find that the MAT 83(Fu Change Foam)constitutive model has the highest calculation accuracy.