Study On The Impact Dynamics Of Three-dimensional Negative Poisson's Ratio Star-shaped Structure

As new type of materials,negative Poisson's ratio mechanical metamaterials have those advantages as unusual overall deformation behavior,high impact resistance,adjustable structural parameters,and stable mechanical properties,etc.At present,most of the research on the impact resistance of negative Poisson's ratio mechanical metamaterials stays on the twodimensional level,and rarely involves three-dimensional.Mostly,finite element software is them are used to simulate the mechanical response under impact,and few experimental study is carried out.Compared with the two-dimensional one,the three-dimensional negative Poisson's ratio mechanical metamaterial has the advantages of lighter weight,higher material utilization,and easier application in practical engineering.In this paper,the traditional twodimensional negative Poisson's ratio star structure is extended to a new type of threedimensional negative Poisson's ratio star-shaped structure.Through impact experiments and finite element simulations,the deformation behavior mode and mechanical response under different impact speeds,as well as the energy absorption characteristics and impact resistance performance under different design angles have been intensively studied as follows:(1)Three-dimensional negative Poisson's ratio star-shaped structure design.Based on the traditional two-dimensional negative Poisson's ratio star-shaped structure,a new type of threedimensional negative Poisson's ratio star-shaped structure is designed according to its two deformation modes: concave and rotating.And the size of the star angle is controlled by designing the angle to 3Ds Max software is used to build the models of the threedimensional star-shaped structure with of 20° and 40°,which then are printed out by using3 D printing technology.(2)Research on impact resistance and energy absorption characteristics of threedimensional negative Poisson's ratio star-shaped structure.The impact dynamic tests were carried out on the 20° and 40° three-dimensional negative Poisson's ratio star-shaped structure models to explored the effects of different impact velocities on the deformation behavior,mechanical response and energy absorption characteristics.It is observed that the experimental models can produce the negative Poisson's ratio effect,and its cell structure showing concave and rotational deformation.(3)Finite element numerical analysis of a three-dimensional negative Poisson's ratio starshaped structure.ABAQUS software is used to establish the three-dimensional star structure models with four design angles,revealing the influence of impact velocity and model design angle on model deformation dynamic evolution,mechanical response and energy absorption,and proposes new ideas for the design and application of energy absorbing structures.In addition,reliability of the experimental results and the accuracy of the finite element calculation model,are further verified.