Study On Mechanical Characterization And Energy Absorption Characteristics Of Non-homogeneous Lattice Structure

As a lightweight porous material that has emerged in recent years,lattice material has excellent mechanical properties such as ultra-light,high porosity,high specific strength,high specific stiffness,high toughness and high energy absorption due to its unique configuration.In the design practice of structural impact resistance and vibration reduction design,it is found that the uniform lattice structure under dynamic load will always produce a large initial stress peak at the same time in its impact area,which will easily lead to the destruction of the structure and adversely affect the energy absorption of the structure.In order to effectively reduce the initial stress peak and improve the energy absorption efficiency,a class of non-homogeneous lattice structure with functional graded characteristics has been designed,and has great application value in civil engineering field,but there are few studies on its mechanical properties characterization.In this paper,the mechanical characterization and energy absorption properties of non-homogeneous functional graded lattice structures are systematically investigated.The main research works and results are as follows:(1)The equation solution of the asymptotic homogenization method was realized by combining the theoretical method of asymptotic homogenization with the finite element analysis method,and the implementation process of the asymptotic homogenization finite element program was elaborated.The equations were solved by the asymptotic homogenization method,and the mechanical parameters of the representative cell were obtained,and an accurate prediction system of the equivalent elastic parameters of the fine model in the nonhomogeneous lattice material was established.(2)A 2D non-homogeneous hierarchical gradient lattice structure was independently proposed and designed,and a variety of different hierarchical self-similar gradient modes were proposed.The functional gradient design and energy absorption characteristics were studied,and the force-displacement curve during impact,the influence law of functional gradient coefficient on the energy absorption characteristics of the structure,the deformation pattern of energy absorption structure under different gradient modes,the change law of specific energy absorption(SEA),the peak crushing force(PCF)were obtained.The effects of different structural design parameters on the energy absorption and impact resistance characteristics of the 2D graded non-homogeneous lattice structure were revealed.(3)A 2D non-homogeneous honeycomb functional gradient lattice structure was independently proposed and designed,and a variety of different hierarchical self-similar gradient modes were proposed.The functional gradient design and energy absorption characteristics were studied,and the force-displacement curve during impact,the influence law of functional gradient coefficient on the energy absorption characteristics of the structure,the deformation pattern of energy absorption structure under different gradient modes,the change law of SEA,PCF were obtained.The effects of different structural design parameters on the energy absorption and impact resistance characteristics of the 2D honeycomb functional gradient lattice structure were revealed.(4)A 3D non-homogeneous functional gradient lattice structure was proposed and designed independently.A variety of 3D non-homogeneous lattice structures with different gradient modes were proposed,and the functional gradient design and energy absorption characteristics of this structures are carried out.The force-displacement curve during impact,the influence law of functional gradient coefficients on the energy absorption characteristics,the energy absorption characteristics under different gradient modes,the variation law of SEA and PCF were obtained through experimental verification and numerical simulation.The effects of different structural design parameters on the energy absorption and impact resistance characteristics of this structure were revealed.(5)A multi-objective Kriging agent model was established,and a multi-objective optimization analysis model of non-homogeneous functional gradient lattice structure was established by the non-dominated ranking genetic algorithm II(NSGA-II),and multi-objective optimization for different functional gradient designs was achieved,and the Pareto frontier of multi-objective optimization was obtained,and the minimum distance selection method(TMDSM)was used The optimization results were evaluated.The gradient patterns,gradient coefficients,material properties,geometric dimensions,etc.on the energy absorption characteristics of 2D/3D non-homogeneous functional graded lattice structures were revealed,and the structures with the best energy absorption characteristics were obtained.(6)ABAQUS was used to establish a refined finite element model for ship collision analysis,and a set of functional gradient lattice structure bridge pier protection device was designed independently,and the structure was applied to bridge structure protection.The simulation calculation and analysis of the energy absorption characteristics during the whole ship impact process were carried out,and the impact force time course curves were obtained,the stress distribution law,energy absorption characteristics and damage mode of the functional gradient protection device were revealed,the influence of various factors such as collision angle and gradient mode on the effectiveness of the graded lattice structure collision protection device was studied,and the energy absorption mechanism and damage law of this type of structure under ship impact were further revealed.