Research On Design,fabrication And Impact Energy Absorption Characteristics Of Lightweight Three-dimensional Gradient Sandwich Structure

The composite sandwich structure has excellent characteristics such as light weight,high specific stiffness,high specific strength,etc.,and is widely used in aerospace,ship and ocean,vehicle transportation,biomedicine and other fields.Compared with the traditional sandwich structure,the new lattice sandwich structure and the ordered porous three-dimensional negative Poisson’s ratio structure have the advantages of low relative density,large porosity,controllable deformation,and strong designability.Many engineering aspects such as vibration reduction have broad application prospects.At the same time,the idea of preparing artificial materials through bionic gradient design has also received great attention in the design and research of new materials.The continuous change of the structural gradient can effectively reduce the interface stress,maximize the advantages of each core layer,and improve the structure.The ultimate strength and energy absorption capacity.However,there is still relatively little research on combining the two organically to make their advantages complement each other,thereby effectively improving the comprehensive mechanical properties of structures.Based on the above background,this paper designed and prepared a hybrid multi-layer gradient lattice sandwich structure and a three-dimensional gradient double-arrow negative Poisson’s ratio structure.The mechanical response of the structure under quasi-static flat compression and dynamic impact was systematically studied.Theoretical analysis,The combination of numerical simulation and experimental characterization reveals the influence of geometric parameters,topological configuration,gradient configuration,filling material and impact velocity on the impact and energy absorption characteristics of the structure.The research work mainly includes the following contents:First,based on the hybrid design idea,the hybrid single-layer lattice sandwich structure of carbon fiber composite panel and aluminum alloy lattice core was prepared by the interlocking assembly process.The method of numerical simulation combined with experimental verification was used to study the structure in quasi-static flat compression And the deformation mechanism,failure mode and energy absorption characteristics under the action of dynamic impact reveal the influence of the relative density of the core on the compressive strength and energy absorption efficiency of the structure.The results show that the higher the relative density of the core,the higher the compressive strength of the structure and the better the energy absorption efficiency.Secondly,based on the bionic gradient design idea,a variety of hybrid multilayer gradient lattice sandwich structures of different specifications were designed and prepared.The static and dynamic mechanical behavior of the structure was studied through quasi-static flat compression and dynamic impact tests.Based on the three-dimensional Hashin failure criterion and Johnson-Cook model,a finite element model of hybrid gradient lattice sandwich structure is established,and the relative density of core,gradient design and filling material are given to the structure deformation mechanism,failure mode,compressive strength and energy absorption efficiency.The law of influence.The results show that the compressive strength of the hybrid multi-layer gradient lattice sandwich structure filled with polyurethane foam is not the linear superposition of unfilled and pure foam,but greater than the sum of the two;the numerical simulation and the experimental results are in good agreement,verifying the value The accuracy of the model provides a reference for subsequent simulation analysis of the mechanical response of composite materials under dynamic impact.Finally,based on the two-dimensional double-arrow negative Poisson’s ratio structure,an enhanced three-dimensional gradient double-arrow negative Poisson’s ratio structure was designed,and the additive manufacturing technology was used to realize the preparation of structures of different sizes.The macroscopic Poisson’s ratio and elastic modulus of the structure are derived based on the canonical equation of the force method and the Moore’s theorem.The quasi-static compression and dynamic impact characteristics of the structure are systematically studied by a combination of experimental characterization and numerical simulation,and the gradient design and The influence of parameters such as impact velocity on structural deformation mechanism,failure mode,compressive strength and energy absorption efficiency.