Investigation On Mechanical Behavior Of Origami Metamaterial Based On Shape Memory Polymer

Shape Memory polymer(SMP)is a kind of intelligent polymer material,which can change shapes and functions in response to specific excitations.Based on its advantages of self-induction,self-drive,diverse excitation modes and shape memory,it has become one of the popular functional materials in current research.4D printing technology,an important method for rapid prototyping of complex structures,combines the advantages of intelligent materials and additive manufacturing and provides further development and application for SMP.As an ancient folk art,origami has the characteristics of diversified deformation,light weight,high strength and flexible design.It has a broad application prospect in aerospace,architectural structure and other fields.Starting from the idea of origami structure and combining the advantages of mechanical properties of SMP smart materials,this paper constructs two kinds of intelligent origami structures through 4D printing technology and studied their mechanical properties in depth.The details are as follows:(1)The mechanical properties of SMP material RGD8530 is characterized.Uniaxial tensile test,Dynamic mechanical analysis(DMA),stress relaxation test and cyclic loading-unloading test are used to characterize the basic thermodynamic and mechanical properties of SMP materials,so as to determine the viscoelastic parameters of the materials.Combined with the three-dimensional constitutive equation,the material parameters are imported into ABAQUS for finite element analysis of metamaterials.(2)This paper adopts a 4D printing method with shape memory polymer to create Kresling origami metamaterial with tunable stress-strain curves,controllable compression twist deformation,shape programming and self-expansion,and developed its deformation theory model.The effects of unit structure parameters and temperature field on the mechanical properties and functional deformation of the metamaterial are analyzed by experiments,theory model and finite element method.The metamaterial can not only switch between monostable and bistable,but also expand from single level to multiple levels.It absorbs energy by folding deformation to mitigate impact,and its mechanical properties can be adjusted by temperature and parameters.(3)A kind of curved origami metamaterial based on SMP is designed and studied.The effects of geometric parameters and temperature on mechanical properties of the metamaterial are analyzed by compression experiment and finite element simulation.Through the competitive relationship between the panel and the crease,the metamaterial can not only achieve positive to negative stiffness,but also adjust the positive and negative values of the in-plane Poisson’s ratio and the out-of-plane Poisson’s ratio.A unique quasi-zero stiffness structure is tested for vibration isolation and its excellent performance of low frequency vibration isolation is verified.