Embedded Hierarchical Reinforcement Mechanism And Mechanical Response Of Three-Dimensional Lattice Structure

Due to the advantages of low density,high specific stiffness,high specific strength and good designability of light lattice structure,it has broad application prospects in the fields of bearing,energy absorption,heat insulation and seismic isolation of railway vehicles.Based on the conventional lattice structure,this thesis introduces the hierarchical strategy.The embedded strut-reinforced hierarchical lattice is designed.Focusing on the mechanical response and energy absorption characteristics of three-dimensional ordered hierarchical lattice structure,the hierarchical reinforcement mechanism and mechanical response of the structure are explored.Main works are listed as follows:(1)Based on the conventional body centered cubic(BCC)structure and face centered cubic(FCC)structure,the strut-reinforced hierarchical lattices BCCH and FCCH are designed by using the embedded self-similar hierarchical principle.A mathematical model used to characterize the spatial relationship of lattice structures with arbitrary geometric configurations is constructed,and the formulae of relative density of lattice structure and diameter-length ratio are given.(2)BCC,FCC and their corresponding hierarchical metal lattice structures are prepared.Using the method of quasi-static compression test and finite element analysis,the deformation evolution mode and the formation process of plastic hinge are captured,the energy dissipation mechanism in the crushing process is revealed,and the hierarchical reinforcement mechanism is defined.After introducing the hierarchical design,the specific energy absorption of BCC and FCC lattice structures increases.(3)The energy absorption characteristics of hierarchical lattice structure under the action of multiple factors such as different relative density(different rod diameter ratio,different diameter length ratio,different outer contour size,etc.)and different orders are explored.The results show that the specific energy absorption of hierarchical structure increases with the increase of relative density in the reasonable design range.Compared with the hierarchical order,the influence of relative density on mechanical properties plays a leading role.(4)Taking the hierarchical lattice structure as the research object,the re-reinforcement of hierarchical lattice structure is studied and analyzed from three aspects: the anisotropy of BCCH lattice structure,the hierarchical regulation of FCCH lattice structure and the matching of inner and outer cells of hierarchical lattice structure.There are 59 figures,8 tables and 100 references in the thesis.