Design And Mechanical Properties Analysis Of New Multi-stage Porous Structures With Negative Poisson’s Ratio

The negative Poisson’s ratio structural material has many advantages,such as large shear modulus,high energy absorption efficiency,high specific strength and specific stiffness,and unique "tension expansion" effect,which make it have a broad application prospect in aerospace,military,medical and other fields.As a special structure widely existing in nature,hierarchical structure has been widely concerned in the field of engineering and scientific research.Most of the tubular structures are used as energy absorption devices.Most of them have positive Poisson’s ratio,but the research on negative Poisson’s ratio is less.Therefore,this paper mainly uses the method of topology optimization to design and study several new multi-stage negative Poisson’s ratio porous structure models,and in-depth analysis of its special mechanical properties,which has important guiding significance for the design and analysis of components.This paper mainly uses the finite element method to carry on the numerical simulation analysis to the designed structure,and combines the theory analysis and the experiment to carry on the comparative analysis to the numerical simulation result,verifies the reliability of the finite element analysis result,thus obtains the accurate mechanical characteristic of the studied structure.The details are as follows:(1)Using ANSYS/APDL parametric modeling method,four kinds of tubular porous structures are established.The influence of the structure surface dent size parameters on the mechanical properties of model one and the difference of the mechanical properties of the topological structures produced by four different topological modes are studied and discussed.3D printing technology was used to prepare the specimen and its quasi-static compression experiment was carried out.The mechanical properties of different topologies,such as the equivalent Poisson’s ratio,the equivalent stiffness,the deformation mechanism and so on,are studied through the comparison of the finite element numerical simulation and the experimental results.(2)Four kinds of octahedral truss structures are built based on the above four kinds of porous tubular structures,and the mechanical properties of the structures are studied by the finite element equation derivation and finite element numerical simulation.The equivalent stiffness of octagonal truss cell under the action of axial horizontal pressure and lateral load is studied in detail.Based on MATLAB and ANSYS,the numerical simulation method is used to verify and analyze.(3)Using ANSYS/APDL software programming method to build concave hexagon and regular hexagon cellular structure respectively,and then merge the two cellular structures with web structure respectively,that is to get web hierarchical structure based on concave and regular hexagon cellular structure.Then,based on ANSYS software,the static mechanical characteristics of the system are analyzed;based on ABAQUS software,the dynamic mechanical characteristics of the system are analyzed.Two groups of six specimens were prepared by 3D printing technology,and the axial compression test was carried out.The experimental results were compared with the results of finite element numerical simulation and some theoretical calculation results to verify the accuracy.