Design And Experimental Verification Of Lightweight Bionic Structure Based On Additive Manufacturing

Bionic structures are characterized by high complexity,small structural scale,high degree of optimization and regular structure,and it is difficult for traditional manufacturing technologies to meet the manufacturing needs of complex bionic structures.Conventional bionic structures are mostly designed based on the characteristics of a single biological structure,which greatly limits the comprehensive performance of the structure.Optimizing the layer distribution of the bionic structure has great potential in improving its mechanical properties and energy absorption characteristics.In response to the urgent demand for high specific stiffness,high specific strength,light weight and energy absorption characteristics in the fields of aerospace and automotive component design,this paper uses aluminum alloy(Al Si10Mg)as the raw material to prepare bionic dot matrix structures using Laser Powder Bed Fusion(LPBF)technology for the design of lightweight structures based on the shape and multi-level distribution characteristics of natural biological structures,and conducts research on the microstructure and mechanical properties of bionic dot matrix structures;numerical simulations are used to study the compression performance,energy absorption characteristics and failure modes of the lightweight bionic dot matrix structure and to verify them with each other with experimental results,the main work is as follows:(1)Using a bionic approach,five bionic dot matrix structures were designed based on the characteristics of biological structures in nature:uniform dot matrix structures A and B,interval gradient dot matrix structures C and D,and continuous gradient dot matrix structure E.The volume,relative density,elastic modulus and yield strength of the single cell and monolithic structure were obtained by theoretical calculations,and the energy absorption equation was also given.(2)The microstructure characterization of the bionic dot matrix structure was carried out.The results show that the bionic structure specimens have a high degree of densification,reaching 99.27±0.25%.The physical phases of the structural specimens are mainlyα-Al and Si phases,with grain size at～1μm;EBSD results show that the structural organization has a high dislocation density,and large angular grain boundaries are predominant,all above 99.4%,triggering changes in plastic strength.(3)By studying the compression performance and energy absorption characteristics of the bionic dot matrix structure,the research results show that the mechanical load-bearing capacity and energy absorption of structure B are optimal,and its specific stiffness,specific strength and specific energy absorption are 69.49 MPa/(g/mm3),217.60MPa/(g/mm3)and 0.34 J/Kg,respectively.Among the gradient dotted structures,structure E has higher specific stiffness and specific strength than structures C and D.The specific stiffness and specific strength ratios are 56.10 MPa/(g/mm~3)and 122.37 MPa/(g/mm~3),respectively;the specific energy absorption of structure C is higher than structures A,D and E by 4.35%,14.29%and 4.35%,respectively.The thicker the wall thickness,the greater the load-bearing capacity and the greater the ability to absorb energy,but the less lightweight.Taking into account the lightweight goal,the gradient layer feature enables the structure to have good mechanical properties and energy absorption compared with the uniform dot matrix structure.(4)The compression process of the five bionic dot matrix structures was simulated using the finite element method,and the compression performance and failure modes of the five bionic dot matrix structures were investigated.The results show that the uniform structures A and B show uniform deformation process under compression load;the spaced gradient structures C and D deformation pattern is"Z"deformation zone and symmetric folding deformation;the continuous gradient structure E shows a layer-by-layer collapse pattern.When the strain reaches 40%,the damage zones of all five bionic dot matrix structures extend along the whole structure to the bottom layer;the simulation results of the five bionic dot matrix structures are verified experimentally,and the two results are consistent with the error of about 10%.