Structural Morphology And Mechanical Properties Of Programmable Kirigami-Inspired Metamaterials

Kirigami with specific cut patterns can exhibit extraordinary properties such as high elongation ratio,negative Poisson’s ratio,and multistability.This new type of structure also exhibits special properties in the fields of thermals,optics,biomedicine,electromagnetism and engineering structures.However,most of the related kirigami research focuses on the geometric configuration design,and there are still core problems such as difficulty in customizing the kirigami structure,unclear mechanical properties,and low efficiency of modeling and design.In order to promote the application of kirigami metamaterials in the engineering field and ensure that kirigami metamaterials have reasonable deformation response and excellent mechanical properties,the structural morphology and mechanical properties of kirigami structures during the stretching process need to be further studied.On the basis of previous research,this paper combines theoretical research,finite element analysis and experimental verification.Taking the two-dimensional and three-dimensional rotating polygonal kirigami metamaterials as the research objects,systematic research is carried out around the structure,morphology and mechanical properties of the rotating polygonal kirigami metamaterials,in order to fill the current research gaps in the two-dimensional and three-dimensional rotating polygonal kirigami metamaterials.The main research contents are as follows:From the perspective of symmetry,actively control the side length of the basic unit of the two-dimensional low-order symmetric rotating polygon,and gradually reduce the symmetry of the unit cell.Symmetry breaking rotating polygonal kirigami structures are obtained,including C_{3 v},₃C,C_S and ₁C symmetric two-dimensional rotating triangle kirigami and C_4v square I-IV type,C_{2 v} diamond I-IV type,C₂ diamond I-IV type rotating quadrilateral kirigami.Geometric models are established for the 4 types of rotating triangle kirigami and 12 kinds of rotating quadrilateral kirigami.And the analytic equations of the stretching ratio and Poisson’s ratio are deduced for each model.These analytical equations provide theoretical bases for programming the unit cell side lengths on demand.Based on the equivalent truss model of the two-dimensional rotating triangle kirigami,the Poisson’s ratios of the kirigami withC_{3 v},₃C,C_S andC₁ symmetry are calculated by theoretical equations,discrete asymptotic homogenization method and finite element simulation.The three results are in good agreement.Then,based on the discrete asymptotic homogenization method,120,000 groups of the geometric parameters and Poisson’s ratio data about rotating triangle kirigami are generated in batches by code.A multi-layer neural network with a relative error of only 5.73%(V_yx)and 6.74%(V_xy)to predict the structural Poisson’s ratio is trained.Based on Abaqus platform,the plug-in Rotating Rigid Polygon is designed for the preprocessing of 2D rotating rigid polygon finite element simulation.On this basis,the finite element parameter analysis is carried out on the two-dimensional rotating polygon kirigami structure.The effects of hinge width,material properties,lengths ratio and interior angle on the deformation response and mechanical properties are obtained.The experimental verification research is carried out about the finite element analysis model,and the results of the two are basically consistent.Based on the results of the parametric analysis on two-dimensional rotating polygonal kirigami,three programming kirigami combinations that can hide and display information are proposed.Based on Grasshopper platform,a programming kirigami design tool that can design independently kirigami is produced.Actively control the side length of the basic unit of the three-dimensional rotating polygon kirigami tube,and gradually reduce the symmetry of the unit cell.The geometric models of C_{3 v} symmetric and C_S symmetric rotating triangle kirigami tubes and C_4v square I type and C_4v squareⅢtype rotating quadrilateral kirigami tubes are established.Based on Grasshopper,a tool for generating shell structures of rotating polygonal kirigami is designed.The finite element parameter analysis of rotating polygonal kirigami tube is carried out.The effects of parameters such as hinge width,material properties,number of cells,and side-length ratio on deformation response and mechanical properties are obtained.Through the comparative analysis of the experiment and the finite element model,it is found that there is a relatively significant element‘pop-up’phenomenon when the rotating polygon kirigami tube is stretched axially.The effects of geometric parameters on deformation response and mechanical properties are analyzed.This is of great significance for the application of rotating polygonal kirigami tubes.