Design Of Novel Cellular Structures With Impact Resistance Properties

Cellular solid materials not only have excellent strength,stiffness and energy absorption properties,but also have the characteristics of low relative density and high designability.Therefore,as light-weight and high energy absorbing material,cellular solid materials are widely used in many fields such as machinery manufacturing,aerospace,civil engineering and so on.With the continuous development of the technology,old conventional cellular solid materials can not meet the requirements for material properties.In order to keep the advantage of low density of cellular solid materials and have other functions with the needs of modern engineering,new cellular solid materials have come into being.Introducing the design of hierarchical structure and auxetic structure into cellular solid materials undoubtedly injects new vitality into the subject of cellular materials.In this paper,the new cellular structure will be taken as the research object,and the design concept of hierarchical structure is introduced into honeycomb materials to design hierarchical honeycomb structures;3D auxetic foam structures are designed to expand the auxetic structure in open-celled foam materials,and the mechanical model of underwater tunnel filled with 3D auxetic foam structures is established.Aiming at cellular materials’ shortcomings,the corresponding improved models are optimized to obtain new cellular materials with higher specific strength,stiffness and energy absorption properties.The mechanical properties of the new cellular materials,such as relative density,collapse stress,compression deformation mode and energy absorption performance,are studied by means of theoretical analysis and numerical simulation.The main contents of this paper are as follows:(1)Combined with the configuration of hierarchical honeycomb structures,the relative density and collapse stress are deduced theoretically.The variation laws of hierarchical honeycombs are analyzed to determine the optimal structural dimension parameters.(2)The impact simulation models of hexagonal hierarchical honeycombs with wall angles of 30° and 45° are established.The impact deformation modes are observed and the causes of these deformation modes are analyzed.(3)The energy parameters of hexagonal graded honeycombs in the impact resistance simulation are analyzed.By comparing the energy absorption properties between hierarchical honeycombs and traditional honeycombs,it’s obtained that the hexagonal hierarchical honeycombs behave much more better on energy absorption performance.(4)For the underwater tunnel model filled with 3D auxetic foam structure,combining the 3D auxetic foam structure and its improved model,the expressions of relative density and collapse stress are derived theoretically and the variation rules are obtained.The most suitable size design parameters and different impact directions are discussed.(5)The simulation models of underwater explosion resistance of underwater tunnel constructed by the 3D auxetic foam structures and its improved model are established.The deformation modes of tunnels are discussed.The optimization effects of 3D auxetic foam structure and its improved model in underwater tunnel anti explosion process are analyzed,and the comparison between these two models is analyzed.(6)The energy parameters of the 3D auxetic foam structure and its improved model in the simulation results are analyzed.By comparing the kinetic energy and specific energy absorption of the 3D auxetic foam structure and its improved model,the 3D auxetic foam materials and traditional solid materials,the advantages of the 3D auxetic foam structures and the improved model and their strengthening effects on underwater tunnel are discussed.