Dynamic Response Of Elastic/Viscoelastic Cellular Materials Under Impact Load

Multicellular materials have unique mechanical properties in nature.As an ideal energy absorbing material,they are widely used in many projects.It has become one of the focuses of academic research to make full use of the energy absorption characteristics of multicellular materials and realize their optimal design.Viscoelastic materials also have excellent energy dissipation performance.How to combine the two excellent energy absorption characteristics effectively to develop energy absorption materials with excellent impact resistance is of great significance for engineering and life shock absorption.Based on the finite element simulation,a composite structure model of different porous elastic materials / elastic viscoelastic materials is established in this paper.The effects of cell shape,material parameter ratio,viscoelastic dissipation rate ratio and impact velocity on the energy absorption characteristics of materials are discussed.The main contents of this paper are as follows:(1)Researching the energy absorption capacity and dynamic response of elastic cellular materials with different cell shapes under different impact velocities;The basic elastic multicellular structure model is established.Under the condition of different cell mass,the propagation process of elastic wave in the multicellular structure and the dynamic deformation process of the model in the process of large deformation compression are analyzed in detail.The dynamic deformation process of the specimen and its micro structure is given.Based on the in-plane impact performance of square,circular and hexagonal cellular structures,the dynamic deformation mechanism and energy absorption capacity of cells with different shapes under in-plane impact load are given.The results show that the energy absorption capacity of hexagonal cell is the strongest,followed by the ring,and the square cell is the weakest.(2)Researching the energy absorption capacity and dynamic characteristics of elastic viscoelastic integrated cellular structure under different impact velocities and viscoelastic deceleration rates;In the case of a certain mass,the integrated multi cell structure model of square cell of elastic-plastic frame and ring cell of viscoelastic filler is established.The influence of different impact velocity and viscoelastic deceleration rate on the in-plane impact performance of multi cell materials is discussed.The energy absorption capacity of the integration of elastic viscoelastic materials under in-plane impact load is obtained.The results show that the larger the velocity is,the stronger the energy absorption capacity is in the same strain range,and the stronger the energy absorption capacity is in the same impact velocity under the same viscoelastic decay rate.(3)Researching the in-plane impact properties of elastic viscoelastic materials with different cell shapes;Based on a certain mass,at low speed,medium speed and high speed respectively,an integrated multi cell structure model of ring and hexagonal cellular elastic viscoelastic materials with better energy absorption capacity is established.The influence of different cell shapes on the energy absorption rate of their combined multi cell structure is analyzed in detail and the dynamic response is obtained.The results show that the energy absorption capacity of the elastic viscoelastic integrated structural model of hexagonal cell is stronger than that of the circular cell at different speeds.