| Carbon neutrality provides new challenges and opportunities for the development of my country’s engineering equipment industry.Among the many emission reduction technology approaches,lightweight technology occupies a very important position.The lattice structure has many excellent properties such as ultra-light,high strength,heat insulation,heat transfer,impact resistance,etc.With the maturity of additive manufacturing technology,the lattice structure is widely used in aerospace,automobile transportation and other fields.As a new type of lightweight,high-strength and multi-functional structure,the lattice structure can maintain the overall mechanical properties while reducing weight,and is an effective means to realize the lightweight of complex parts.Aiming at the problem that the overall internal force of the part is not considered in the manufacture of lattice structures and the design of lattice filled parts,this topic studies a design method of lattice structure filled parts based on additive manufacturing.The lattice cell is used as the design unit.Combined with the additive manufacturing process,the homogenization method is used to obtain the mechanical properties of the lattice structure,and the design of the variable configuration and variable density lattice structure filling parts is realized according to the topology optimization of the density distribution.The main research contents of the thesis are as follows:(1)Manufacturability analysis of lattice structure additive manufacturing.According to the characteristics of lattice structure,the concept of manufacturing element is adopted to define lattice structure as data of geometry,material and process information.Taking the fused deposition modeling process as an example,combined with the forming characteristics of the lattice structure,according to the specific manufacturing machine and process conditions,different strut structures were designed and manufactured and tested experimentally,and the manufacturable lattice structure based on this process was obtained.Sexually constrained size.(2)Analysis of the influence of lattice structure manufacturing elements on mechanical properties.Two-level factorial design was used to select five manufacturing element data,and the body-centered cubic and face-centered cubic lattice structures were manufactured and compressed.The elastic modulus of each specimen was obtained and a multiple linear regression equation was established.The analysis found that the manufacturing element The geometric data of the lattice cell type,cell size and strut diameter have a greater impact on the elastic modulus.(3)Construction of equivalent model for mechanical properties of lattice structures.A method for analyzing mechanical properties of lattice structures based on homogenization is adopted,and a library of equivalent mechanical properties among five regular lattice cell topologies,relative density,elastic modulus,and Poisson’s ratio is established to draw three-dimensional elastic properties.The modulus map provides a reference for the selection of the part filled lattice cells.The lattice structure compression experiment of ABS material was carried out,the failure mode of lattice structure was analyzed,and the stress-strain curve and elastic modulus were obtained.Compared with the homogenization method,the results were in good agreement.(4)The design method of lattice structure filled parts is proposed.First,analyze the working conditions of the part and divide the design area;then,based on the equivalent mechanical performance library of the lattice and topology optimization,determine the filling position,type and density of the lattice structure of the part;finally,replace the lattice with a homogeneous entity with the same mechanical properties The structure is used for simulation analysis.The vehicle bracket parts were designed by the proposed method,and the mechanical properties of the front and rear bracket parts were compared and optimized using finite element simulation.The feasibility of the design method is verified.To sum up,this topic selects lattice cells as the design unit,and studies a design method of lattice structure filled parts,which integrates the two scales of microscopic cells and macroscopic parts,and realizes the optimal design of lattice structure filling of parts.The overall mechanical properties are reduced while the mass is reduced.This research provides a reliable technical approach for the design and rapid manufacturing of lattice structures,and has important reference significance for enhancing the mechanical properties of parts and the lightweight efficiency. |
